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"Towering cerebellum" is a classic finding for what anomaly? Chiari II. Look also for corpus callosum dysgenesis/agenesis, tectal beaking, medullary kinking, caudal displacement of the brainstem, and myelomeningocele
What is Devic disease? neuomyelitis optica (NMO), autoimmune disease [possibly] targeting aquaporin-4 transmembrane channel proteins, presenting as optic neuritis and myelitis extending at least 3 vertebral levels. Impossible to differentiate from ADEM on first episode.
Name this disease: autoimmune disease targeting aquaporin-4 transmembrane channel proteins, presenting as optic neuritis and myelitis extending at least 3 vertebral levels. Impossible to differentiate from ADEM on first episode. neuomyelitis optica (NMO), aka Devic disease
What is the eponym associated with neuomyelitis optica (NMO)? Devic disease. Autoimmune disease [possibly] targeting aquaporin-4 transmembrane channel proteins, presenting as optic neuritis and myelitis extending at least 3 vertebral levels. Impossible to differentiate from ADEM on first episode.
Single episode of self-limited myelitis symptoms and MR showing involvement of <2 vertebral segments, also >2/3 the axial cross-sectional area of the cord. No further episodes. acute transverse myelitis. Differentiate from NMO (Devic disease), ADEM, and multiple sclerosis, and from masses such as astrocytoma, or dural fistula.
Brainstem lesion with faint brush-like enhancement and mild hypointensity on T2* GRE. capillary telangiectasia, aka capillary malformation. Congenital malformation, not a neoplastic process like capillary hemangioma.
Above what thickness of cartilage cap should one be concerned for malignant transformation of an osteochondroma? >1.5 cm. Malignant transformation to chondrosarcoma usually results in much larger cap.
What is a Tornwaldt cyst? Notochordal remnants resulting from adhesion between pharyngeal diverticulum and notochord. Presents incidentally as unilocular proteinaceous cyst at midline of posterior nasopharynx. No treatment or follow-up necessary.
Incidental unilocular cyst at midline of posterior nasopharynx, between the longus colli muscles, surrounded by normal enhancing mucosa. T2 bright, T1 variable, variable suppression on FLAIR. Tornwaldt cyst. Notochordal remnants resulting from adhesion between pharyngeal diverticulum and notochord. Proteinaceous contents cause variable T1 signal and FLAIR suppression. No treatment or follow-up necessary.
What portion of patients treated with radiation therapy develop a second brain neoplasm? What is the most common second neoplasm to occur in these patients? 3-12% get second neoplasms. Meningiomas make up 70%. Gliomas and sarcomas are rare at 20% and 10%, respectively.
What is the most common location for skull base chondrosarcoma? petrooccipital fissure (POF). Look for avid enhancement, high T2 signal, and POF centered lesion. Only 50% will have chondroid matrix.
What percent of neurofibromas are solitary and not associated with any syndrome (nonsyndromic)? 0.9
What is the most common cause of a cranial mass involving scalp and dura in a middle-aged or older patient? metastasis by far. Consider also plasmacytoma. LCH is a disease of childhood. Osteomyelitis is rare in the cranium but is common around the sinuses and mastoids.
Fibroadenoma on breast biopsy is a benign entity and generally requires no further workup (if imaging is concordant). What two subsets of fibroadenoma DO require excision? giant fibroadenoma (>10cm) and juvenile fibroadenoma (<18yo). There exists enough uncertainty in these lesions that excision (lumpectomy) is routinely advised.
30yo. Slow-growing, moderate nodular enhancement, expansile, painless, multiloculated multilobulated mixed cystic & solid ("bubbly") mass in posterior mandible or in premolar-1st molar region of the maxilla, associated with unerupted tooth. Top Dx? DDx? Ameloblastoma, aka adamantoblastoma, adamantinoma (old terms, no longer used). Locally aggressive, will recur if not resected en toto. DDx: dentigerous cyst & keratocystic odontogenic tumor. Periapical cyst or abscess. Odongogenic myxoma. ABC, FD.
Given the following choices, which is best to describe a choroid plexus mass in a middle-aged or older adult?: Abscess, choroid plexus papilloma/carcinoma, meningioma, metastasis, cavernous malformation. Metastasis should be top Dx. A distant second would be meningioma. Ref: RadPrimer
T/F: Virchow-Robin spaces can cause obstructive hydrocephalus. True. '"Tumefactive" enlarged perivascular spaces can cause mass effect and obstructive hydrocephalus. They behave "just like" cerebrospinal fluid (CSF) even though they contain interstitial fluid (not CSF).' Ref: RadPrimer
What is Erdheim-Chester disease (ECD)? Rare monoclonal proliferation of non-Langerhans dendritic cells (a non-Langerhans cell histiocytosis), lipid-laden macrophages, multinucleated giant cells, lymphocytes and histiocytes, onset in middle age, sclerosis in long bones. ST masses, pulmonary.
Symmetric posterior white matter disease with leading edge enhancement and sparing of subcortical U fibers. Top Dx? X-linked adrenal leukodystrophy. Disordered peroxisomal fatty acid oxidation resulting in accumulation of very-long chain fatty acids, most severely affecting the myelin in the central nervous system, the adrenal cortex, and Leydig cells in the testes.
Pt with tinnitus. Temporal bone CT shows tiny soft tissue nodule along the medial middle ear space, with normal internal carotid artery. Top Dx? glomus tympanicum (inferior tympanic nerve, aka Jacobson nerve). Make sure the carotid artery is not aberrant. 1/4 hereditary, 10% bilateral, 3% malignant. Octroscan (preferred) or MIBG.
40yo with very slow growing enhancing cauda equina mass with evidence of hemorrhage and hemosiderin deposition. Top Dx? myxopapillary ependymoma. WHO grade I lesion without risk of malignant degeneration, but may have local seeding or subarachnoid dissemination, and can have subarachnoid hemorrhage.
What is myxopapillary ependymoma? WHO grade I cauda equina lesion spanning 3-4 levels without risk of malignant degeneration, but may have local seeding or subarachnoid dissemination, and can have subarachnoid hemorrhage. Slow growing. Peak age 30-40yrs.
Name 6 discontinuous types of lesions in patients with Gardner syndrome. Familial adenomatous polyposis (FAP), desmoid tumors, osteomas (head/neck dense bony excrescences, not osteoid osteomas), supranumerary teeth, and congenital hypertrophy of the retinal pigment epithelium (CHRPE).
At what size should an AML be referred for removal? Why? >4 cm. Risk of life-threatening hemorrhage.
What is adenoma malignum? Indolent bulky cancer of the cervix with grape-like multicystic mass, often seen in Peutz–Jeghers. Bad prognosis.
Peutz–Jeghers patient with bulky cervical tumor with multiple grape-like cysts. Top Dx? adenoma malignum. Indolent, slow growing, but bad prognosis.
What malignant renal cell tumor has a characteristic of relatively low enhancement on sequential postcontrast CT? papillary renal cell carcinoma (also chromophobe renal cell ca)
What is hepatic mesenchymal hamartoma? Uncommon benign multiseptated heterogeneous mixed solid & cystic tumor arising from liver, more a developmental anomaly rather than a cystic neoplasm. Avg age at presentation: 16 months (before 2 yrs), with abdominal enlargement and respiratory distress.
Name 5 cystic hepatic tumors in child <2 years of age. hepatic mesenchymal hamartoma, hepatic abscess, cystic hepatoblastoma, embryonal sarcoma, simple hepatic cyst. Much older children may present with biliary cystadenoma/ca (aka IhMCN), biliary papilloma, hydatid cyst, or amoebic abscess.
What are the salient features of DiGeorge syndrome? (Hint: mnemonic) CATCH-22: Cardiac anomalies (often ToF), Abnormal facies, Thymic aplasia, Cleft palate, Hypocalcemia/Hypoparathyroidism. DGS is aka "22q11.2 deletion syndrome" (hence, "22" in CATCH-22) and velo-cardio-facial syndrome.
Expansile lesion in the petrous apex with "eggshelling" of the posterior border of ICA and the posteromedial cortex, with high signal on T1 and T2. Top Dx? Why the high signal? "PA-CG" or petrous apex cholesterol granuloma. Chronic & subacute blood (hemosiderin and methemoglobin). Pneumatized petrous apex is required (look at other side). May compress IAC. Incidental, or presents with SNHL, tinnitus. If low T1, -->cholesteatoma.
Young child with fusiform enlargement of the bilateral optic nerves on CT and MR, with marked enhancement. Top Dx? neurofibromatosis type 1. Usually unilateral if any, but if both sides this is nearly pathognomonic.
Child with calified lobular cystic and solid suprasellar mass. Hi T1 signal in solid components, not suppressing on T1 fat-sat. Top Dx (statistically)? craniopharyngioma
What special MR sequence(s) must be performed in the evaluation of hormonal pathology thought to be of pituitary origin? Multiphase sequential postcontrast thin-cut T1 to detect microadenoma which may be isointense to normal pituitary on noncontrast T1/T2. They enhance, but more slowly than normal pituitary, hence the multiple phases. Look laterally in the sella.
Name the hormones secreted by 3 common functioning pituitary microadenomas. Prolactin secreting adenomas cause galactorrhea, hypogonadism, amenorrhea, infertility, and impotence. Growth hormone secreting adenomas cause acromegaly, or gigantism in children. Adrenocorticotrophic hormone secreting adenomas cause Cushing disease.
Subdural effusions are associated with which pathologic history?: prior trauma, prior meningitis, prior GBM, recent surgery, or prior seizures prior meningitis. In prior history of trauma, one can see chronic subdural hematoma and/or subdural hygroma (from arachnoid tear).
Which is a known complication of the presence of arachnoid cyst: subdural hematoma or subdural hydroma? subdural hematoma (may be chronic)
What is the most common cause of pathologic vertebral body compression fracture in a young child? LCH. Lymphoma and metastasis remain in the differential.
Middle-aged adult with expansile scalloping 4th ventricular mass, CSF signal on T1 and T2, but does not suppress on FLAIR and restricts on DWI. Top Dx? epidermoid cyst. Contain ONLY squamous epithelium and keratinaceous debris.
Define the Nabor classification of spinal meningeal cysts. Type I is extradural not containing any spinal nerve root fibers. Type II cysts are extradural but contain spinal nerve root fibers, such as Tarlov or perineural cysts. Type III lesions are intradural meningeal cysts (the classic "arachnoid cyst").
HIV patient with progressive dementia and brain MR showing fairly symmetric diffuse somewhat hazy white matter T2 hyperintensity, no enhancement or mass effect. Dx? HIVE, or HIV encephalopathy, aka HIV encephalitis, aka AIDS dementia complex. Consider also other causes of cognitive decline (dehydration, malnutrition, protein depletion, substance abuse).
What is THE distinguishing imaging feature of middle ear or petrous apex cholesterol granuloma? T1 hypERintensity (not seen in cholesteatoma)
What potential complications should be screened for in patients being evaluated for acquired cholesteatoma? Look for tegmen tympani dehiscence (CSF leak), lateral semicircular canal dehiscence (inner ear fistula), and facial nerve canal erosion (CN VII injury). 80% of arise from pars flaccida & result in scutal and/or ossicular erosion by mass in Prussak space.
Adult with slowly progressive CNS symptoms and MR showing multilobar infiltrating lesions with diffuse T2 hyperintensity, mass effect that respects cerebral architecture, and minimal to no enhancement. Top Dx? gliomatosis cerebri. WHO grade III. Focal enhancement -->higher grade malignancy, should guide biopsy. DDx broad: arteriolosclerosis (if no mass effect), vasculitis (DWI?), anaplastic astrocytoma (multi?), viral encephalitis, demyelination, PML, lymphoma
T2 hyperintense mid-corpus callosum (CC) lesions in woman in third-fourth degade of life with clinical triad of encephalopathy, bilateral hearing loss, and branch retinal artery occlusions is classic for what disease? Susac syndrome. Caused by microinfarctions; no demyelination on pathology. Peak age 20-40 yrs. F>>M. Usually self-limited (2-4 yrs) but may lead to permanent deafness or blindness.
What is the meaning of "lambdoid-torcular inversion?" Elevation of the torcular Herophili above the level of the lambdoid suture, as is seen in classic Dandy Walker malformation and some lesser forms of this spectrum.
Multiple hamartoma syndrome has an associated eponym. What is it? Cowden syndrome (Lhermitte-Duclos disease + macrocephaly, hamartomatous GI polyps, benign skin tumors (trichilemmomas, papillomatous papules, acral keratoses), and high risk of breast, endometrial, & follicular thyroid ca.
What is Caffey disease? aka infantile cortical hyperostosis, self-limiting, rare, infants <5 mo. Fever, soft-tissue swelling, hyperirritability. XR: double contour of cortex d/t subperiosteal new bone, often spares epiphysis and metaphysis, asymmetric. Ulna, mand, clav.
(Juvenile) granulosa cell tumor
What is giant-cell reparative granuloma? aka "solid variant ABC". Non-neoplastic, reactive lesion of unknown etiology, related to trauma or intraosseous hemorrhage. Occurs in hands, feet, face, and jaw. Lytic, expansile, may thin or destroy cortex. No perisosteal rxn, extraoss mass, or matrix.
Malignant meningeal tumor related to solitary fibrous tumor in other parts of the body (pleural, soft tissues). hemangiopericytoma
Elevated serum alkaline phosphatase and urine hydroxyproline are typical for what bone disease? Paget disease
What medication is associated with hypOdense renal stones? indinavir
What is Turcot syndrome? aka constitutional mismatch repair-deficiency (CMMR-D), association between familial polyposis of the colon, and brain tumors such as medulloblastoma and malignant glioma. Biallelic deletion, unlike Lynch syndrome.
What is Lynch syndrome? aka hereditary nonpolyposis colorectal cancer (HNPCC). AD-inherited dz of colorectal cancer WITHOUT polyps (unlike FAP or Gardner syndrome) and related cancers: transitional CA, duodenal and jejunal adenoCA, and CNS tumors most often glioblastoma.
Patient with postural headaches, MR with widespread dural enhancement and thickening, slumping midbrain, tonsillar descent, subdural hygromas or hematomas, and convex dural sinuses. Dx? intracranial hypOtension. LP low opening pressure <6, hi protein. 2/3 have Marfan or E-D. Causes: spont spinal CSF leak, LP, weak dura, ruptured arachnoid diverticulum, surgery, vigorous exercise/cough, severe deH20, disc herniation or osteophyte (rare).
Eponym for constitutional mismatch repair-deficiency (CMMR-D), association between familial polyposis of the colon, and brain tumors such as medulloblastoma and malignant glioma. Turcot syndrome
Eponym for hereditary nonpolyposis colorectal cancer (HNPCC). AD-inherited dz of colorectal cancer WITHOUT polyps (unlike FAP or Gardner syndrome) and related cancers: transitional CA, duodenal and jejunal adenoCA, and CNS tumors most often glioblastoma. Lynch syndrome
Cafe au lait macules (CALMs): What states are represented by the border patterns in different diseases? Which diseases are associated with which "state?" "Coast of Maine" pattern is associated with McCune-Albright disease. "Coast of California" is associated with NF1 (neurofibromatosis type 1, von Recklinghausen disease).
Week old newborn with mild granular opacities, then worse airspace opacities 2 days later. What should be a tope concern? PDA causing pulmonary edema
What skeletal dyspasia is associated with bouquet-like bunching of the bases of the metacarpals? Morquio disease. Look for central anterior beaking at the vertebral bodies.
Cirrhotic child with cystic renal disease. Top Dx? autosomal recessive polycystic renal disease (a lesser form of renal disease allows survival to develop severe liver disease, cirrhosis).
A presacral cyst contiguous with the thecal sac through an anterior sacral defect is diagnostic of what entity? Anterior sacral meningocele. Enlarged sacral foramen or defect in dysplastic sacrum. Important for surgical planning: determine if nerve roots traverse neck of sac.
What is the name for arthritis and abnormal pigmentation secondary to tissue deposition of homogentisic acid? ochronosis, aka alkaptonuria (also spelled alcaptonuria). Extremely rare homogentisic acid oxidase enzyme deficiency. Brittleness, degeneration of cartilage. Other causes of imaging appearance of spinal degeneration should be high on differential.
What are seronegative spondyloarthropathies? Spondyloarthropathies characterized by negative Rheumatoid factor and syndesmophytes and joint disease, especially SI joints. Includes AS, enteropathic spondylo, PsorA, reactive SpA, and uSpA (undiff).
CT shows soft tissue mass with calcification surrounding the odontoid process (pseudopannus). Dx? Pseudopannus with calcification is diagnostic for CPPD.
Skull base mass involving highest portion of pharynx in a middle-aged patient of Asian descent. Top Dx? nasopharyngeal carcinoma (NPC), endemic in east Asia. Type 2b (III) nonkeratinizing undifferentiated form is most common, and is most strongly associated with Epstein-Barr virus infection.
Middle-aged adult presenting with seizure, CT and MRI show calcified cortical mass in the frontal lobe with no enhancement and no surrounding edema. Top Dx? oligodendroglioma. WHO grade II (or III if anaplastic). 10 yr median survival. Loss of heterozygosity for 1p and 19q (50-70%) protends better prognosis. May involve middle, parietal, or occipital lobes. Most calcify. Half show NO enhancement.
What is the most common intracranial tumor to CALCIFY? oligodendroglioma. Classic presentation: Middle-aged adult presenting with HA and seizure, and CT and MRI show calcified cortical mass. WHO II, 10 yr median survival. Enhancement may portend higher grade (anaplastic, WHO III).
Differentiate pineoblastoma and pineocytoma. Pineoblastoma (PB) = highly malignant WHO grade IV PNET related to retinoblastoma, whereas pineocytoma = WHO grade I pineal parenchymal neoplasm with nodular, target, or ring-like enhancement, usually asymptomatic, can look like nonneoplastic pineal cyst.
robson staging of RCC, article in 2004 abdominal imaging
VHL-associated conditions? (von Hippel Lindau disease) PANC islet cell, microcystic adenoma. ccRCC (freq CausOfDth). CYSTS: panc, renal, liver. PHEO. Hemangioblastoma (CNS: cerebellar~75%, spinal~25%; retinal). Choroid Plexus Papilloma (CPP). EndoLymphat Sac Tumor. AMLs. Epididymal pap cystadenoma.
TS and rhabdomyoma, other assoc'd conditions? pediatric cardiac tumor DDX?
cystic vs solid renal mass differentiation on renal mass protocol CT? numbers? enhancement HU difference of <15 = cyst (hyperdense, likely from hemorrhage). >20 = solid mass (needs mgt, bx, rsxn). 15-20 = equivocal.
CT on patient post-RFA for renal mass shows new fat-containing masslike lesion at RFA sight. Is this a concern? This is likely related to the RFA, not of concern. Not a liposarcoma or AML.
Neuroembryology: what are the two types of neurulation? primary and secondary. primary down to S1-2 (roots?). secondary is the conus, caudal cell mass. myelomeningocele is a defect in primary, specifically a nondysjunction primary neurulation abdnormality.
What is a myelocystocele? Skin-covered spinal dysraphism, can occur anywhere along spine, prefers C-spine.
T/F: All myelomeningoceles and myeloceles are 100% associated with Chiari II malformation (barring any h/o in utero surgical correction). True. If you don't see a Chiari II, then it's not a myelomeningoceles and myeloceles.
Premature dysjunction primary neurulation abdnormality. Lipomyelocele or lipomyelomeningocele, or intraspinal lipoma. Neural crest cells get exposed to central canal, ependymal cells, turn into fat.
Aneurysmal dilation of bowel loops. DDx? lymphoma, metastasis, and GIST. These tend not to cause obstruction.
How does diastematomyelia differ from diplomyelia? In diastematomyelia, duplicated spinal cord fuses caudal to bony or fibrous spur. In diplomyelia, the cord remains duplicated caudally. Remember that diastematomyelia is not a split cord (strictly speaking), since both hemicords have a central canal.
What is the name for progressive demyelination of the corpus callosum with necrosis and atrophy, classically associated with chronic alcoholics? Marchiafava-Bignami disease. A direct toxic effect of chronic high-level EtOH exposure.
T2 hypointense calcified tumor centered in the jugular foramen, with dural tails and permeative-sclerotic changes on bone CT. No flow voids. Top Dx? jugular foramen meningioma
How does one measure nuchal translucency on U/S? Inner to inner (just the fluid). Done between 11 weeks 4 days and 14 weeks 3 days. Abnormal if >3 mm.
What fraction of TS patients have angiomyolipomas? 0.8
What does tardus parvus signify? (2 word phrase) proximal stenosis
What is the normal limit for peak systolic flow in the internal carotid artery (ICA)? less than 125 cm/sec
What are the ultrasound peak systolic flow (PSV) criteria for internal carotid artery (ICA) stenosis of 50-69%, and for stenosis greater than 70% but less than "near occlusion?" 125-230 cm/sec = 50-69% stensosis (low grade). Greater than 230 cm/sec = high grade (>70%) stenosis (not occlusion). Near occlusion results in variable PSV and EDV. Less than 125 cm/sec indicates NO stenosis (less than 50% narrowing is NOT stenosis).
What is the critical lab value to follow for a patient on continuous-rate intra-arterial fribrinolytic therapy? serum fibrinogen. If drops below 150, cut the rate in half. If below 100, stop tPA immediately.
Name 5 important causes of symmetrical basal ganglia T1 hypERintensity. calcium, manganese (hepatic failure, encephalopathy), carbon monoxide poisoning, Wilson disease (copper), Japanese encephalitis, and ?? nonketotic hyperglycemic hemichorea (NHH)
FLAIR-hyperintense (nonsuppressing) nonenhancing nonrestricting subdural fluid collection in a patient with history of treated intracranial infection, no fever, is classic for what Dx? subdural effusion
What immunohistochemical marker is positive in all phases of growth and regression in cases of infantile hemangioma (IH)? GLUT-1
Which nerve sheath tumor (NST) is more associated with cystic change? schwannoma
Middle-aged or older patient with small NONenhancing T2/FLAIR *bright* mass in the lateral ventricle or lateral wall or obex of 4th ventricle. Most likely Dx? subependymoma. Can mimic ependymoma and hemangioblastoma.
Multiple dural-based strongly enhancing masses in a fairly young patient (30s) with an abnormal CXR. Top Dx? neurosarcoidosis. Look also for thickened infundibular stalk, nodular or diffuse lesions along the pial surface, cranial nerve enlargement/enhancement, and parenchymal masses resembling primary brain neoplasm.
Older patient with history of sore throat treated with oral antibiotics several times, but persistent malaise, sore throat, and difficulty swallowing. CT shows swollen, edematous, enhancing aryepiglottic folds and epiglottis. Top Dx? adult supraglottitis
Compare intracranial dermoid and epidermoid cysts. How are they similar? How do they differ? Dermoids usually midline, w/ hair follicles, sweat glands, lipid & cholesterol, follow fat on imaging, rupture, fat droplets cause chemical meningitis. Epidermoid cysts much more common, usually off midline, resemble CSF but not fully suppress on FLAIR.
5 yo with a calcified, enhancing, partially cystic suprasellar mass. Top Dx? craniopharyngioma. 90% calcify, 90% enhance, 90% are partially cystic
Male <20yo with synchronous solid masses in the pineal and sella/suprasellar locations is classic for what entity? germinoma. In this case, pineal + suprasellar germinomas ("double midline atypical teratoma" or bifocal germinoma). The suprasellar component represents a "drop metastasis" from the pineal germinoma. Ref: RadPrimer
T-bone CT shows calcification of the tympanic membrane, ossicular tendons and ligaments, and bony irregularity of the ossicular surfaces, and focal ossifications and debris in the middle ear and mastoid. History of chronic otitis. Dx? tympanosclerosis. Secondary to suppurative chronic otitis media.
A child with microtia and conductive hearing loss is being evaluated with temporal bone CT. What is the critical question the clinician wants answered? Presence or absence of normal stapes and oval window. Important for prognosis and preoperative planning of ossicular reconstruction. Inner ear is typically normal in Congenital External Ear Dysplasia (CEED) (different embryologic origin).
What are the features of CHARGE syndrome? (Name 6 if you can, but at least get the first one.) Coloboma, Heart anomaly, Atresia choanae, Retardation (mental & somatic development), Genital hypoplasia, Ear abnormalities.
What is the most common inner ear anomaly seen in children with congenital sensorineural hearing loss? large vestibular aqueduct anomaly, aka IP-II (incomplete partition, type II). Over 90% bilateral. Hearing intact for first few years of life, but lost over time. Tx: cochlear implantation.
What are the 4 stages of neurocysticercosis? vesicular, colloidal vesicular (cysts with thick, ring-enhancing walls and mild to marked surrounding edema), granular nodular, and nodular calcified. Taenia solium. Fecal-oral transmission (not raw pork). Tx: albendazole and steroids.
Adult with expansile multiloculated and multilobulated mixed cystic & solid mass in the posterior mandible. Top Dx? ameloblastoma
Well-circumscribed, expansile bony cyst with sclerotic border sparing the cortex, surrounding the crown of an unerupted mandibular tooth. Top Dx? dentigerous cyst, aka follicular cyst
Adult with jaw swelling. CT shows expansile solitary posterior unilocular jaw lesion with sclerotic rim, oriented longitudinally in mandible and resorbing roots of teeth. No relation to unerupted crown. Top Dx? keratocystic odontogenic tumor (KOT), previously aka odontogenic keratocyst (OKC). Benign cystic neoplasm of jaw with aggressive behavior & high recurrence rate. Multiple in Gorlin syndrome. Look for calcification of the tentorium and falx. Ref: RadPrimer
What is the name for the prominent anastomotic cortical vein anastomosing with the superior sagittal sinus. vein of Trolard
What is the connection in patients with hemangioblastoma and unusually high hematocrit? Hemangioblastomas can occasionally secrete erythropoietin.
What are the two most common causes of deep cerebral vein thrombosis in a child? Severe dehydration and Factor V Leiden deficiency. Look for hyperdensity of deep cerebral veins, vein of Galen, and straight sinus in comparison to superior sagittal sinus, in association with hypodensity of basal ganglia (ischemia or infarction!).
What is the typical imaging pattern for MELAS? High T2/FLAIR signal in the putamina, may be asymmetric/unilateral. Stroke-like lesions in parietal-occipital lobes, non-vascular distribution. DWI negative if old.
What is the typical imaging pattern for Leigh syndrome? Bilateral, symmetric high T2/FLAIR signal in putamina and peri-aqueductal gray matter. Leigh syndrome is a mitochondrial encephalopathy, similar to MELAS, more severe, presents by age 2, respiratory failure and death in childhood.
Older child with enlarged optic nerve and multiple T2 hyperintense foci in the globi pallidi, thalamus, brainstem. Top Dx? NF1. The WM lesions are not demyelination, but rather foci of myelin vacuolization and astroglial proliferation.
What are the most common causes of spontaneous nontraumatic intracerebral hemorrhage in patients under of age of 45? AVM, drug abuse, venous infarction and vasculitis
T/F: A keratocytic odontogenic tumor (KOT) can show internal enhancement. False. The keratinaceous contents of KOT do not enhance. If you see internal nodular enhancement in a unilocular expansile lesion in the posterior mandible, think unilocular ameloblastoma. (They are USUALLY multilocular.)
Match: Vertebral body vs. posterior elements. GTC vs. ABC. Which more frequently occurs where? ABC: posterior elements, neural arch. GCT: vertebral body.
Young adult with "bubbly" mass mixed solid and cystic mass with calcification in frontal horn or body of lateral ventricle, with hydrocephalus. Moderate to strong enhancement. Top Dx? central neurocytoma. Glycine peak on MR spectroscopy (MRS). Surgical resection typically curative. 5-yr survival: 90%.
What is the most common newborn tumor? sacrococcygeal teratoma. Ref: RadPrimer
HIV pt w/ subcortical, asymmetric white matter T2/FLAIR hyperintensities, w/o significant mass effect or enhancement. Q1: What is the Dx? Pt undergoes highly active antiretroviral therapy (HAART) and worsens clinically. Q2: What is THIS Dx? Answer 1: PML (progressive multifocal leukoencephalopathy, caused by ubiquitous JC polyomavirus, in setting of immunodeficiency. Answer 2: immune reconstitution inflammatory syndrome (IRIS). Tx with steroids.
What is the formula for quickly calculating the combined effect of biological and physical half-lives? product/sum (of the half-lives) = effective half-life
T-99m and T-99 are which of each other?: isotopes, isobars, isomers, or isotones? isomers (same N, Z; different energy states). Isotones have same N, different Z. Isobars have same A (N+Z), but the N and Z differ. Isotopes, same Z, different N.
Positron emission occurs in radionuclides that have excess of _____. protons (not positrons; atoms don't have positrons)
In positron decay, an element decays to its (isotope, isobar, isomer, or isotone?). isobar. A proton gets converted to a neutron. Mass stays roughly the same (minus tiny mass of positron and a neutrino). Isobars have same A (N+Z), but the N and Z differ. Isotones, same N, different Z. Isomers have same N, A, and Z, but different energy.
What is the natural log of one-half? This is useful for understanding radiodecay and its calculations. ln(0.5)= -0.693 Hence, that number appears in the half-life formula: A = S * exp(-0.693*t/T) where A is ending activity, S is starting activity, T is half-life, and t is time interval.
Name three GI polyposis syndromes that form typically ADENOMATOUS polyps. FAP, Turcot syndrome, Gardner syndrome
Name three GI polyposis syndromes that form typically HAMARTOMATOUS polyps. Peutz–Jeghers syndrome, Cowden syndrome, Bannayan–Riley–Ruvalcaba syndrome ("banana man, or BRR")
The "chain of lakes" appearance of dilated pancreatic duct suggests what pathology? pancreatitis
Esophageal ulcerations greater than 1 cm are given WHAT NAME? Name two underlying pathologic processes responsible for these. "giant esophageal ulcer" is greater than 1 cm diameter. CMV, HIV
What pathology can mimic the appearance of esophageal varices on static image esophagram? varicoid esophageal cancer. Dynamic fluoro images will differentiate the two. Varices will compress and transiently disappear with swallowing.
Why is it important to differentiate pyloric channel ulcers from duodenal or gastric ulcers? Pyloric channel ulcers are treated like duodenal ulcers, with triple Abx therapy, and do not connote the high risk of cancer that gastric ulcers entail.
What does the reverse 3 sign mean on duodenal fluoroscopy? pancreatic cancer. The ductal papilla is tethered to the pancreatic duct, so mass impinges on the duodenum AROUND the papilla, causing the reverse 3 appearance on contrast fluoroscopy.
What does the appearance of "cone cecum" suggest? Crohn disease. Look for other signs (creeping fat, string sign, cobblestoning, fistulae).
What is the classic small discrete enhancing tumor in the medullary conus of the spinal cord? myxopapillary ependymoma
What is indicated by the MR spectroscopy peak(s) at 1.3 ppm? Broad methyl(CH3)- and methine(CH2)-group resonances centered at 0.9 and 1.3 ppm, respectively, of free fatty acids from cell membrane breakdown. So-called "lipid-lactate" peak (doublet). Lactate flips on longer TE, differentiating from lipid.
Name the peaks at 2, 3, and 3.2 ppm on MR spectroscopy. NAA @ 2.0 ppm, creatine @ 3.0, and choline @ 3.2. Choline (membrane precursor) is normally < creatine (reference peak, energy metabolism). NAA (neuronal protein) peak height is a measure of normal brain.
What is the difference between kV and keV? Kilovoltage (kV) is a unit of electrical potential or voltage (across anode and cathode in x-ray tube), whereas keV is a unit of energy (used in discussing energies of photons, electrons, positrons, etc).
What is the relationship between changes in kVp and subsequent changes in x-ray intensity at the image receptor? Increase in x-ray intensity at image receptor is proportional to 5th power of fractional change in kVp. Equation: (x)^5=y, where x= fractional change (1.10=10% incr, 0.7=30% decr) and y= factor of intensity change, to be compensated for by mAs adjustment.
An increase in kVp by 15% results is what change of radiation intensity at the image detector? Increasing kVp by 15% leads to 2.01x (rough doubling) radiation intensity at image detector, adjusted for by halving the mAs at the x-ray tube. (x)^5=y, where x= fractional change (1.10=10% incr, 0.7=30% decr) and y= factor of intensity change.
For a given filament size, as the anode angle is decreased, what is the effect on apparent focal spot size and on heat load capacity? DECREASING anode angle DECREASES apparent focal spot size and DECREASES heat load capacity.
Foveal search fixation times correlate with true vs. false positive and negative findings on a radiographic image. Which fixations are longer on average: True positive or false negative? True positive or false positive? Fixation time in shorter to longer: true negatives < false negatives, and true positives < false positives
Relative to what line is the anode angle measured? The axis of the anode-cathode setup? or perpendicular to this axis? The plane perpendicular to the axis (parallel to the anode plate). Lower anode angle (going form 14 to 12 degrees) leads to greater heel effect, smaller APPARENT focal spot on the detector, and (miniscually) lower heat loading capacity.
Radiographs in a child show unilateral bony overgrowth at the medial aspect of the tibial plateau epiphysis. No h/o hemophilia. Top Dx? dysplasia epiphysealis hemimelica, aka Trevor disease
Diagnostic mammogram and US shows a round mass. Of breast malignancies, what are the most likely histologies? "Peanut M&M": Papillary, Mucinous, and Medullary are all round on Mammo/US.
Brain MR shows multiple hemorrhagic masses. What are the likely primaries for mets? "MR CT BB": Melanoma, Renal cell RCC, Choriocarcinoma, Thyroid carcinoma (and teratoma), Bronchogenic carcinoma, Breast carcinoma
What is the INNER diameter of a 9 French catheter? NOT SPECIFIED. French sizes are based on EXTERNAL diameter, which in this case would be 3 mm. Fr= D(mm)*3. A 3 French catheter has a 1 mm EXTERNAL diameter. Devised by Joseph-Frédéric-Benoît Charrière, a 19th-century Parisian surgical instrument maker.
Patient with TIPS is in IR for TIPS eval. What is the allowable window for peak systolic velocity (PSV) before proceding to revision? No more than 190 cm/sec. No less than 90 cm/sec (some say down to 50 cm/sec is okay).
What is the most common underlying pathologic cause of subclavian steal? atherosclerosis
Onion skin mass in testicle. Top Dx? testicular epidermoid cyst
What size of splenic artery aneurysms require treatment (coiling)? What three populations have higher risk of rupture? Treatment is indicated for aneurysms larger than 2 cm. Higher risk for pregnant patients and patients with portal hypertension or liver transplants.
What percent of Marfan patients have annuloaortic ectasia? Annuloaortic ectasia is present in 75% of patients with Marfan syndrome.
What pulmonary abnormality is often seen in patients with Marfan syndrome? paraseptal and bullous emphysema predisposing to spontaneous pneumothorax
What screening test is appropriate to evaluate for in patients with hereditary hemorrhagic telangiectasia (HHT)? What is another name for this disease? Echocardiogram "bubble" test, screen for R-to-L intrapulmonary shunt and initiate evaluation of pulmonary AV malformation (pAVM). Screen also for cerebral arteriovenous malformations (cAVMs) and liver lesions. Osler–Weber–Rendu syndrome.
Recurrent epistaxis, mucocutaneous telangiectasias of the lips, mouth, and tongue, visceral arteriovenous malformations of the brain, lung, liver, and mesentery, and first-degree family relatives with similar findings. Top Dx (has two names)? hereditary hemorrhagic telangiectasia (HHT), aka Osler–Weber–Rendu syndrome
What negative contrast agent is available for patients needing a fluoroscopic interventional procedure (such as IVC filter placement) but cannot receive iodinated contrast due to renal insufficiency or anaphylactic allergy? carbon dioxide (delivered as microbubbles)
Y-90 has what half-life and depth of tissue penetration? Y-90 is a pure beta emitter, decaying with T1/2 of 64.1 hr to Zr-90. Tissue penetration 2.5 mm (avg) and 11 mm (max), based on β energy 0.937 MeV (mean) and 2.28 MeV (max).
What anatomic variant can lead to high risk of hemorrhage in setting of pelvic fracture and often missed extravasation in setting of normal internal iliac arteriogram? Replaced obturator artery arising from inferior epigastric or external iliac artery. So-called "corona mortis" configuration ("crown of death"), due to it's import in pelvic trauma.
Describe the best (personal) two-handed tie approach (4 throws total). (IR concept) Guns first (left-handed two-hand), then thumbs (right-handed two-hand), then an MF (L-handed one-hand) and an IF (R-handed one-hand).
Describe the Curacao criteria and what they are used for. Dx of Osler-Weber-Rendu, aka Hereditary Hemorrhagic Telangiectasia (HHT), requires 3 of 4 criteria: 1) spontaneous recurrent epistaxis, 2) multiple telangiectasia (proximal GI), 3) proven visceral AVM (lung, liver, brain), 4) 1st-deg family member.
What is Paget–Schroetter disease? upper extremity DVT, typically in axillary or subclavian veins. Reported to occur after vigorous or repetitive activity, or as result of thoracic outlet syndrome, or spontaneously. Rarely causes fatal PE. aka "effort thrombosis"
In performing transjugular liver biopsy, how should the needle be oriented in the right hepatic vein? in the middle hepatic vein? Point needle ANTERIOR in the right hepatic vein. POSTERIOR biopsy in the middle hepatic vein.
Chronic abdominal pain. Angiography shows asymmetric narrowing of the proximal celiac artery, upward hooking, and poststenotic dilatation accentuated on expiratory images but persistent on inspiratory imaging. Dx? median arcuate ligament syndrome (MALS)
An operator of a fluoroscopy unit that has capability of reporting Peak Skin Dose (PSD) should be notified at which thresholds (in mGy) during any one particular case? First notification at 2000 mGy, then every 500 mGy after that. Patient follow-up is recommended if PSD > 3000 mGy. Ref: SIR guidelines, J Vasc Interv Radiol 2009; 20:S263-S273.
An operator of a fluoroscopy unit that has capability of reporting reference point air kerma (K[a,r]) should be notified at which thresholds (in mGy) during any one particular case? First notification at 3000 mGy, then every 1000 mGy after that. Patient follow-up is recommended if K[a,r] > 5000 mGy. Ref: SIR guidelines, J Vasc Interv Radiol 2009; 20:S263-S273.
An operator of a fluoroscopy unit that has capability of reporting kerma-area-product (P[KA]) should be notified at which thresholds (in Gy*cm^2) during any one particular case? First notification at 300 Gy*cm^2, then every 100 Gy*cm^2 after that. Patient follow-up is recommended if P[KA] > 5000 mGy. Ref: SIR guidelines, J Vasc Interv Radiol 2009; 20:S263-S273.
An operator of a fluoroscopy unit that has capability of reporting only fluoroscopy time (FT) should be notified at which thresholds (in Gy*cm^2) during any one particular case? First notification at 30 min, then every 15 min after that. Patient follow-up is recommended if FT > 60 min. Ref: SIR guidelines, J Vasc Interv Radiol 2009; 20:S263-S273.
What are the 3 main features of Pierre Robin syndrome? severe micrognathia, posterior cleft palate, glossoptosis (airway obstruction caused by posterior displacement of the tongue base). May be caused by genetic anomalies at chromosomes 2, 11, or 17.
What is the most well-differentiated histologic cell type among thyroid cancers? Follicular cell is more well-differentiated than papillary, which is more well-differentiated than mixed follicular-papillary cell.
How is thyroid uptake calculated? Describe the formula. Neck uptake (minus leg background) divided by same-dose capsules in neck phantom (minus room background).
Name four causes for hyperdense liver on a noncontrast CT. Hemochromatosis, hemosiderosis, Wilson disease, amiodarone liver
What is the upper limit of normal hepatic parenchymal density (in HU) on noncontrast CT? 75 HU
What is the sensitivity of esophagram to detect esophageal leak? about 50%. True existing leaks (from trauma, Boerhaave, Mallory-Weiss) are often missed, around half of the time.
KERMA is an acronym. What does it stand for? KERMA: Kinetic Energy Released to MAterial.
What is range of radiation exposure (dose) that causes 50% mortality in 60 days? This is the "LD 50/60" which for humans is somewhere between 3.5 and 7 Gy depending on the level of care.
What clinical sign/Sx is earliest indication of whole-body radiation exposure and best triage parameter? Vomiting: if starts <1hr after exposure (>4Gy), hospitalize and txfr to special rad’n mgt ctr. 1-2hrs post exposure (2-4Gy), to burn ctr or hem/onc center. 2-3hrs post expos. (1-2Gy), gen hospital 3 wks. No vomiting (<1Gy), outpt surveillance 5 wks.
What 5 cancers (organ systems) are most frequently associated with radiation exposure? leukemia, thyroid, breast, lung, and gastrointestinal tract
What is the excess risk of childhood cancer from in utero exposure to radiation? (in % excess risk per Gray of radiation dose) approximately 6% per Gy. Ref: RSNA physics module on Radiation Effects
What is the Joint Commission's skin dose threshold (absolute dose and % relative to planned dose) for defining a “sentinel event” trigger? Skin dose of greater than 1500 rad (15 Gy) any field (or >25% of planned dose) during a cardiac, vascular or interventional fluoroscopy procedure is a “sentinel event” per JC. Ref: RSNA physics module Fundamentals of Radiation Protection
How long must radioactive waste be stored before discarding in regular trash? Stored securely for 10 physical half-lives. A survey must then be done to demonstrate ZERO detectable radioactivity above background before disposing in non-regulated waste.
How soon after a medical event involving radiopharmaceuticals must the event be reported? to whom? by what methods? By telephone to the NRC or the appropriate Agreement State regulatory agency, and to referring physician, within one calendar day, and in writing within 15 days, and to patient if referring physician deems safe.
What is the lifetime excess absolute risk (EAR) of cancer attributable to 1 Sv (1000 mSv) of whole-body radiation effective dose (averaged for whole population)? 5% plus or minus 1%, but the curve is strongly age-dependent. Children have up to 15% excess risk per Sv. Ref: RSNA physic module Radiation Dose and Risk.
What is the ICRP and NCRP recommended dose limit for the lens of the eye for a member of the general public? 15 mSv/yr. Whole body dose limit is 1 mSv/yr. Skin or extremity dose limit is 50 mSv/yr.
Describe the formula for geographic unsharpness. Geographic unsharpness (Ug) = f * ODD / SOD, where f= focal spot size, ODD= object to detector distance, and SOD= source to object distance. Based on fact that all parts of the focal spot produce x-rays, and angles of parts are slightly different.
Describe the formula for the inverse square law for beam intensity from a point source. Intensity (I) = 1 / (d^2) where d= distance from point source of beam.
Why does increasing the SOD result in less image blur? What effect does decreasing the ODD have? Increasing source to object distance results in tighter grouping on detector of photons arising from the focal spot from different angles due to nonpoint nature of focal spot. Decreasing the ODD has a similar effect (less blur) for similar reasons.
Define the relationship between SID, SOD, ODD, and magnification. Magnification (M) = I*O = SID/SOD = (SOD+ODD)/SOD, where I= image size, O= object size, SID= source to image distance, SOD= source to object distance, and ODD= object to detector distance. SID=SOD+ODD
What is the Beer-Lambert Law? Exponential drop in x-ray intensity as it passes through a material. I=I(0)e^(-mu*x) where I= intensity (before(0) and after material), mu= attenuation coefficient, and x= thickness.
Define "Bucky Factor." Bucky Factor = dose with grid in place divided by dose without the grid. Usually ~2-3. IOW, it is necessary to increase the skin-entrance exposure to the patient by a factor of 2 or 3 when using a grid to maintain statistical (low noise) quality.
What is a "Bucky?" The "Bucky" is the (typically moving) grid holder in a stationary (non-portable) x-ray unit. Portable units do not have Bucky grids; grids have to be added manually(?).
A KUB on a patient recently treated for unresectable prostate cancer shows a very blurry black blob of overexposure in the region of the lower central pelvis. What is this? Fog. X-rays or gamma rays from implanted brachytherapy beads in the prostate are causing emission exposure on the detector or film.
What is the S/P ratio in the context of plain radiography? scattered/primary ratio. Quantifies the degree to which scattered photons affect image contrast. C = C(0) / (1 + S/P), where C(0) = relative contrast in absence of scatter, C = in presence of scatter.
In mammography, what direction are the electrons moving in the x-ray tube? (toward the patient, or away from the patient?) Why? Away from patient. Cathode is on patient's end; anode (target) is away from patient. Heel effect results in higher x-ray flux toward pt's chest, where tissues are thicker, compared to target side (nipple side) where tissues are thinner.
MR shows thin hypointense halo around the pancreas with a "sausage-shaped" pancreas associated with signs of cholangitis and thyroiditis. Top Dx? autoimmune pancreatitis. May be multi-system, as in this case.
How does the prognosis for periosteal osteosarcoma compare with that of parosteal osteosarcoma and of conventional osteosarcoma? prognosis for periosteal osteosarcoma is similar to that of parosteal osteosarcoma, and both are much better (far less aggressive) than that of conventional osteosarcoma. Lung mets are still possible.
What is the principle driver of the superior spacial resolution in mammography? small focal spot size
Intramuscular (buttocks) nonencapsulated T1-hypointense lesion, bright on fluid-sensitive sequences (T2, STIR) with characteristic rim of fat around superior and inferior poles of lesion. CT density between that of fluid and soft tissue. Top Dx? intramuscular myxoma. Peak age 40-70 yrs. ~66% female. Benign. No risk of malignant degeneration.
In fluoroscopy, how is minification gain expressed in terms of diameters of input and output phosphors? IOW, what is the equation? "Square D over d." Minification Gain = [D(in)/d(out)]2, where D(in) is the diameter of the input phosphor, and d(out) that of the output phosphor.
What happens to field of view and minification gain as a fluoroscopist increases magnfication? Goes up/up? up/down? down/down? down/up? down/down. Field of view and minification gain both decrease in mag view. Decreases in minification gain can be compensated by increases in flux gain to maintain total brightness gain.
How is total brightness gain related to flux gain and minification gain in a fluoroscopy unit? Brightness Gain = Flux Gain x Minification Gain
Why are Image Intensifiers (fluoro) replaced when Conversion Gain (Gx) decreases to 50% of baseline? Decreased Gx leads to compensatory increases in mAs by the AEC to maintain brightness on the output phosphor, and thus increased patient dose. Alternatively, increased compensatory aperture settings lead to increased image noise.
What is vignetting? Decrease in light intensity at the periphery of a fluoroscopy image using II. Distance from focusing point to output phosphor varies. The path is closest at the center of the output phosphor and it is farther at the edge of the output phosphor.
Described the calculation for vertical resolution in a TV system (used in II fluoroscopy). Vertical Resolution (Rv) in mm = number of Raster Lines (R, 480 true for a 525 line TV) multiplied by Kell Factor (k, generally 0.7), divided by twice the field of view in mm. Rv=Rk/(2*FOV)
Described the calculation for horizontal resolution in a TV system (used in II fluoroscopy). Resolution (Rh) = bandwidth * fH / [R * 60 frames/sec * AR * FoV(mm)], where fH = Horizontal Fraction of bandwidth used to display image data, R= Raster Lines (525 specified = 480 true), and AR = Aspect Ratio = TV frame width / height, usually 4/3=1.333
MR of knee shows hypointense linear band of tissue oriented just off-parallel to the ACL to which it lies anterior in the intercondylar notch. What is this? infrapatellar plica, aka ligamentum mucosum, the most common plica in the knee. The other two common plica include the suprapatellar and mediopatellar types. Lateral is rare.
T/F: Metastatic calcification is seen primarily in cancer patients. False. Metastatic calcification is deposition of calcium salts in otherwise normal tissue because of elevated serum calcium, due to deranged metabolism or increased absorption or decreased excretion of calcium, as seen in hyperparathyroidism.
In fluoroscopy, what is the maximum federally allowable skin entrance dose rate in normal mode? measured at how far from the image receptor? 10 R/min (Roentgen), or 87 mGy per minute, measured at 30 cm from image receptor
In fluoroscopy, what is the maximum federally allowable skin entrance dose rate in high-dose mode? measured at how far from the image receptor? any special requirements? 20 R/min (Roentgen), or 174 mGy per minute, measured at 30 cm from image receptor. Requires audible/visual indicator.
In fluoroscopy, what is the % of dose to the operator from scatter from the patient as measured at 1 meter? approximately 0.1% (0.001) of the patient entrance radiation dose. Typical GI fluoro scatter doses without shielding would be about 0.5-1.5 mGy/hr.
What number (range) of spot images give patient skin dose equivalent to 1.0 minutes of routine fluoroscopy? 5 to 10 spot images give patient skin dose equivalent to 1.0 minutes of routine fluoroscopy.
At one meter distance from the patient, perpendicular to the beam direction, what is the dose to the operator from scatter? At one meter perpendicular to the beam direction, scatter is approximately 1/1000 of the patient entrance skin dose. Inverse square law applies at higher distances. (one quarter this dose at 2 m, one ninth at 3 m, etc)
According to the JC, “an unintended cumulative dose of greater than ____ Gray to a single field“ constitutes a sentinel event. 15 Gy. Ref: RSNA modules
What is the Latinized term for characteristic pattern of Paget disease in the cranium? osteoporosis circumscripta
What is osteoporosis circumscripta? characteristic pattern of Paget disease in the cranium
What is the Latinized term for Paget disease? osteitis deformans
What infectious pathogen (category/subcategory, not species) is associated with Paget disease? paramyxovirus
Erlenmeyer flask appearance in long bones, marrow replacement on MR/CT. Type of lipid storage disease. What is it? Gaucher disease
Name the eponym for avascular necrosis of the vertebrae. Kummel disease, often occurs following a traumatic collapse. An intra-vertebral vacuum cleft may be seen (accentuated on extension view), although not specific.
Describe the equation for pitch in CT. (aka beam pitch) Pitch = Beam Pitch = distance table moves per revolution / beam width. Pitch of less than 1 means overlapping slices (better pictures). Greater than 1 means gaps between slices (lower dose).
Describe the equation for "slice pitch" in CT. (aka detector pitch) Slice pitch (SP) = detector pitch = distance table moves per revolution / slice width. SP is also ratio of beam pitch to slice thickness. If each slice is represented by a single detector, then slice width = detector width. For SDCT, slice pitch = 1.
What are the units of linear attenuation coefficient? Linear attenuation coefficient (µ) has units of inverse length, 1/cm or cm-1.
What does the term "raysum" mean? Attenuation measured along a ray of X-rays, affected by attenuation coefficient of each tissue/material weighted to its proportion of the total material, or attenuation coefficient in each pixel summed over the total number of pixels in the ray.
What are the two linear attenuation coefficient reference points by which all others in a particular tissue are determined? metal? water? bone? fat? vacuum? air? linear attenuation coefficient of water (zero HU) and that of vacuum (-1000 HU)
How is pixel size related to matrix size and field of view? What is the equation? pixel size = field of view / matrix size
Between T2 and T2*, which MR signal weighting is more resistant to field inhomogeneities? T2, which relies on 180 inversion pulse to rephrase xy magnetization vector. Curve for T2 decay follows the peaks of signals, rather than the signal itself. T2* follows the signal itself (decaying much more rapidly due to field inhomogeneities).
If your MR images show phase wrap, or “wrap around” artifact, how can you get rid of this? Increase the field of view.
T/F: Doubling the NEX doubles the signal to noise ratio. False. Doubling the NEX doubles the scan time but only increases the SNR by sqrt(2)=1.414.
T/F: Doubling the NEX doubles the scan time. True. Doubling the NEX doubles the scan time but only increases the SNR by sqrt(2)=1.414.
Which sequence has the highest signal-to-noise ratio? T1, T2, PD, or T2*? PD has highest signal-to-noise (then T1, then T2, then T2*)
What common brain tumor has restricted diffusion? lymphoma
What is Hunter’s angle and should it be positive or negative? In MR spectroscopy, the angle between horizontal axis and line between choline and NAA peaks, should be positive from choline to NAA (line goes up), in usual orientation of spectrum with 0 to the right. IOW, NAA should be higher.
A 15% increase in kV causes a ___ % increase/decrease in the number of x-rays produced (area under the curve on spectrum of photons as function of kV). 100% increase (doubles)
What is the k-edge of iodine? 33.2 keV (or just 30)
What is the k-edge of tungsten? 69.5 keV (or just 70)
What is the k-edge of molybdenum? 20.0 keV (or just 20)
What is the k-edge of rhodium? 23.2 keV (or just 23)
What is the k-edge of barium? 37.4 keV (or just 37)
Doubling the number of photons or x-rays in an image acquisition does what do the signal-to-noise ratio? increases SNR by sqrt(2). Follows poisson statistics: Standard deviation, SD, is a measure of signal to noise ratio, where N is the signal. SD=sqrt(N). If N doubles, SD increases by sqrt(2).
In CT, decreasing slice thickness does what to signal-to-noise ratio? resistance to partial volume averaging? xy-plane contrast resolution? Decreasing slice thickness decreases SNR, increases resistance to partial volume averaging, and decreases xy-plane contrast resolution (which is more susceptible to changes in SNR than partial volume averaging).
T/F: CTDIvol is a reasonable representation of the patient dose for patients of all sizes and shapes. False. CTDIvol is a reasonable representation of the patient dose only if the CTDI phantom diameter (16 or 32 cm) is a reasonable model for actual patient anatomy with respect to attenuation (which is rarely the case).
What A and Z values (odd or even?) for elements result in a net magnetic nuclear dipole moment? The A (mass number) must be odd, OR Z (atomic number/element) must be odd. If both are even, then no magnetic dipole.
Doubling the external magnetic field B0 causes what effect on the T2 of most biological tissues? (decrease? increase? remain the same?) remain the same. Unlike T1 spin-lattice relaxation times which increase in stronger fields, T2 spin-spin relaxation times are intrinsic properties of any tissue or substance, and are not affected by field strength. Measured from t(100%) to t(37%).
What is the gyromagnetic ratio (γ) for H1? 42.58 MHz/Tesla. Therefore, the Larmor frequency for hydrogen protons in a 1.5 T Bzero is 63.87 MHz.
In which type of MRI Pulse Sequence does "T2 blurring" occur? fast spin echo. During echo-train collection, the xy echoes gradually decrease for each k-spice line (blurring T2), which alters T2 weighting and reduces the sharpness of the image. Half-Fourier transform is typical.
What pulse sequence is useful for MR imaging when high-resolution images are needed but inhomogeneity and magnetic susceptibilities in the magnetic field (perhaps from metal) preclude the use of gradient echo or other faster sequences? fast spin echo. Retains resistance to inhomogeneity and magnetic susceptibilities. T2 blurring occurs in 3D image acquisition schemes.
If the residual transverse magnetization of a GRE sequence is “spoiled” after the echo data are acquired, image weighting will generally be what? T1? T2? T2*? or PD? T1-weighted. The T2-weighted signal is reduced when transverse magnetization is spoiled.
Are inversion recovery GRE images (MPRAGE and 3DFSPGR) weighted toward T1, T2, T2*, or PD? Are there multiple options? IR GRE sequences are heavily T1 weighted. (not multiple options)
Which of the following parameters in spin echo brain MR imaging results in T1-weighting? TR near brain T2 values? TR near brain T1 values? TE near brain T2 values? TE near brain T1 values? TR near brain T1 values (bright signal for short-T1 tissues such as white matter and fat)
Which of the following parameters in spin echo MR imaging results in T2-weighting? TR near brain T2 values? TR near brain T1 values? TE near brain T2 values? TE near brain T1 values? TE near brain T2 values (bright signal for long-T2 tissues such as CSF)
In 3D MR image acquisition, which gradient(s) is/are used twice? slice select and phase encoding gradients are both doubly produced to allow for slab select and slice encoding.
For a 3D fast spin echo pulse sequence, what are the factors that affect the image acquisition time and how are they related? Image acquisition time = TR x Np x NEX x S / ETL , where TR is time to repeat, Np is
In gradient-echo imaging, which "weighting" can inversion recovery be used to control? T1? T2? T2*? PD? Fluid? Fat? Bone? In GRE, IR can be used to control T1 weighting.
What values are generally longer: T1 spin-lattice relaxation times or T2 spin-spin relaxation times? For any given tissue, the T1 relaxation times are roughly an order of magnitude LONGER than the T2 spin-spin relaxation times. For instance, T1 for muscle is around 870 msec, but the T2 is around 50 msec. T1 for CSF is around 4000, but T2 is around 2000.
What happens to spin-lattice relaxation times (T1) of most tissues as Bzero increases? What about T2 relaxation times? T1 spin-lattice relaxation times become longer and closer to each other as Bzero increases. Image contrast becomes more difficult to achieve, even though signal-to-noise ratio improves. T2 times do not change.
What is the stable operating temperature at which superconducting MR coils are maintained via liquid helium? 4.2 Kelvin (-269 C) is typical
What is the principle danger of very high slew rates in MR imaging? induction of peripheral nerve stimulation in the imaged patient
In MR instrumentation, what is the term used to describe the ellipsoidal volume available for patient imaging, defined by the three perpendicular diameters? specification volume
In MR imaging, what is the term used to describe the RF power (in watts) absorbed per kg of patient, also describing the potential for tissue heating? Specific Absorption Rate (SAR). Inhomogeneity of the RF field leads to asymmetrically high local heating (energy absorption) rather than distributed to the entire person, leading to the concept of "local SAR."
What is the term used to describe the alteration of MFG pulse shape to reduce the image artifacts caused by eddy currents? pre-emphasis
What is the rate of magnetic field strength falloff in relation to distance from the isocenter? Field strength is inversely proportional to distance cubed (in contrast to light/radiation, which falls off by the square of distance).
Forty percent of patients with lateral ankle sprain also have injury to this major medial ligament. Which is it? deltoid ligament. Medial and lateral ligament disruptions constitute ankle instability.
Name 2 unique tumors that both cause a "split fat sign" on MR. synovial sarcoma, and malignant peripheral nerve sheath tumor (extremely unlikely to be intramuscular)
Middle aged patient with painless lump in extremity. MR shows intramuscular T1 hypo-, T2 hyperintense mass with mild heterogeneous enhancement and flame shaped material along periphery of mass, extending along muscle fibers. Top Dx? intramuscular myxoma. The flame-shaped extension from the lesion along muscle fibers is specific but not sensitive, thought to relate to leakage of the central material.
What is the normal range of Bohler's angle? 20-40 degrees
Lead bullets and shrapnel are often left in the body. At what orthopedic location do these fragments have high risk of causing lead poisoning? Why? Intra-articular lead causes reactive synovitis, high resorption of lead with clinical consequences.
The 3 most frequently seen aggressive lytic primary bone tumors in the 30-60 yr age range include malignant fibrous histiocytoma, primary osseous lymphoma, and what other cell type? Don't forget fibrosarcoma.
What is an Essex-Lopresti fracture? Severely comminuted radial head fracture in combination with proximal migration of the radial shaft and disruption of the distal radioulnar joint (DRUJ), usually with dorsal subluxation/dislocation.
Trauma patient has radiographs showing a severely comminuted radial head fracture in combination with proximal migration of the radial shaft and disruption of the DRUJ with dorsal subluxation/dislocation. What is the eponymous name for this fracture? Essex-Lopresti fracture
What is multicentric reticulohistiocytosis? aka lipoid dermatoarthritis, infiltration of lipid-laden histiocytes into (skin, bone, cartilage, synovium), resulting in triad of ST nodules, acroosteolysis, & destructive polyarthritis (usually IP joints, less frequent wrist, shoulder, hip, knee)
Chronic joint pain, with radiographs showing acroosteolysis, & distinctly erosive interphalangeal arthritis, soft tissue nodules, and no "sausage digit" swelling. Top Dx? multicentric reticulohistiocytosis. Lack of sausage digit sets it apart from psoriatic arthritis and reactive arthritis. Acroosteolysis sets it apart from RA.
What 2 inflammatory arthropathies typically feature "sausage digit" swelling? chronic reactive arthritis (CRA) and psoriatic arthritis (PSA)
What is the principle distinction between an ALPSA lesion and a Perthes lesion? Medial displacement of the anterior glenoid labrum fragment in ALPSA, not seen in Perthes. Both are Bankart variants and both retain attachment to the periostium.
What is spondyloarthropathy of dialysis? Disk space narrowing and endplate destruction (visible on radiographs) due to crystal deposition in the endplates and disk in the setting of chronic renal disease and dialysis.
15yo with knee pain and knee radiographs showing huge joint effusion, overgrowth of the epiphyses, and widening of the intercondylar notch. Top Dx? hemophilia. Hyperemia is cause for epiphyseal overgrowth.
What is Milwaukee shoulder? Complete tear of the rotator cuff with associated joint destruction, effusion containing hydroxyapatite and CPPD crystals, hyperplasia of the synovium, and multiple osteochondral loose bodies.
Athlete with groin pain, muscle strain of pectineus and rectus abdominus muscles, and adjacent bone marrow edema. Top Dx? athletic pubalgia, aka "sports hernia." No actual hernia required (actually rare).
Name the wrist extensor compartments and their respective tendons and landmarks. Numbered 1-6: 1. aductor pollicis LONGUS, extensor pollicis BREVIS; 2. ext carpi radialis LONGUS & BREVIS; [Lister tubercule] 3. ext pollicis LONGUS; 4. ext indicis proprius, ext digitorum communis; 5. ext digiti minimi (spans DRUJ); 6. ext carpi ulnaris.
What are the landmarks for correct positioning of the tunnels for a bone-tendon-bone ACL graft? Center of tibial tunnel on tibial plateau = 2 cm from anterior tibial line. Center of femoral tunnel = intersection of posterior femur line and Blumensaat line (roof of intercondylar notch as seen on lateral radiograph).
What site is most "classic" for neuropathic (Charcot) arthropathy in diabetics? tarsometatarsal (Lisfranc) joint. Ref: RadPrimer
What conditions cause coxa magna and coxa plana? developmental dysplasia of the hip (look for a dysplastic acetabulum), SCFE (look for medial or posterior displacement of femoral head), septic hip (see extensive cartilage destruction), or old Legg-Calvé-Perthes disease (if none of the others fit).
Patients with what type(s) of osteogenesis imperfecta can expect to live a normal life span? OI types I and IV may live a normal lifespan. Note that marked hypertrophic callus formation may occur at fracture sites in these patients.
Which type(s) of osteogenesis imperfecta is/are lethal soon after birth? OI type II is lethal in the perinatal period. (Type III has high childhood mortality, and types I and IV can have a normal lifespan).
What soft tissue sarcoma nearly always arises in the subcutaneous tissue and often/usually fungates outward? Dermatofibrosarcoma protuberans (DFSP) nearly always arises in the subcutaneous tissue and protrudes outward, hence its name. Expect to find no fatty component.
Malignant fibrous histiocytoma has a more preferred name today. What is it? undifferentiated pleomorphic sarcoma
Middle-aged woman with a cystic mass in the pancreas, numerous cysts smaller than 2 cm, stellate central scar with calcification, cystic fluid positive for glycogen. Top Dx? microcystic pancreatic adenoma. Overwhelmingly benign. CT often diagnostic. EUS and bx with aspiration can settle questions. Women 4:1.
Of all ankle tendons, which tendon's sheath is in continuity with the ankle joint space? Only the flexor hallucis longus (FHL) tendon sheath is in continuity with the joint space. Fluid around this tendon is normal.
What ethnic/racial group has a higher risk of developing ankylosing spondylitis (AS) than the general population? Which population has a lower risk? Native Americans have higher risk. African Americans have a lower risk.
Child with bilaterally symmetric trapezium-trapezoid, trapezoid-metacarpal, capitate-metacarpal fusion. Top Dx? juvenile idiopathic arthritis (JIA), virtually pathognomonic for chronic
Young adolescent with radiographs showing regular periosteal reaction extending along the phalanges, soft tissue swelling but no articular abnormality. DDx? (Name 3.) juvenile idiopathic arthritis (JIA), sickle cell dactylitis, tuberculosis dactylitis
Young adult with radiographs showing C2-C6 fusion with hypoplastic vertebral bodies. History of arthritis since age 15. Top Dx? juvenile idiopathic arthritis (JIA)
Diffuse pulmonary uptake on a gallium scan has a differential. Name 4. TB, PCP, CMV, sarcoidosis, diffuse lung metastases, lymphangiogram pneumonitis
What is the eponymous name for this triad: prominent posterosuperior calcaneal tubercle, Achilles insertional tendinopathy, and retrocalcaneal bursitis? Haglund syndrome. The prominent posterosuperior calcaneal tubercle is called Haglund deformity.
Woman with chronic knee fullness has MR showing frond-like intraarticular and bursal masses that follow fat signal intensity on all MR sequences. Top Dx? lipoma arborescens, aka diffuse synovial lipoma, aka villous lipomatous proliferation of synovial membrane. Often seen secondarily in setting of osteoarthritis, rheumatoid arthritis, or prior trauma.
What is the supraacetabular fossa? Normal variant pit characteristically located at the 12:00 position of the acetabulum, in the vicinity of the stellate crease but separate from it. Normal surrounding articular cartilate and underlying marrow.
What is the stellate crease in the acetabulum? A normal shallow puckering in the articular cartilage of the acetabulum located near the 12:00 position, below the resolution of most MR scanners.
At which skeletal site is Salter-Harris IV type the most common Salter fracture type (rather than the usual type II)? lateral condyle fracture. This is not seen radiographically, but MR shows usually a Salter-Harris IV morphology.
Cystic mass in the pancreatic tail favors which cystic adenoma? Microcystic or mucinous cystic? Mucinous cystic adenoma. 50% occur in the tail. Look for fewer than 6 cysts, larger than 2 cm, and peripheral calcifications rather than central, no stellate scar.
Which types of IPMN have lower or higher risk of malignancy? Branch duct type has lower risk of malignancy and can be followed. Diffuse duct type has high risk of malignancy and should be resected.
T/F: Islet cell tumors in the pancreas will NOT have calcifications. False. 1 in 4 has calcifications. (25%)
What 2 arthropathies are known to develop such large subchondral cysts that they can mimic tumor? gout and pyrophosphate arthropathy (pseudogout)
45 year old with thigh mass demonstrating areas that follow fat signal on MR, but also areas that show intense T2 signal, with cystic areas and heterogeneous intense enhancement. Top Dx? myxoid liposarcoma. Areas of T2 hyperintensity are myxoid. Presence of fat exludes other sarcomas.
Young adult male with foot pain, numerous erosions in the MTP and IP joints, and florid periostitis along the phalanges. Top Dx? psoriatic arthritis, then or chronic reactive arthritis (less common than PSA)
Young patient with knee pain, x-rays showing a saucer shaped defect in cortex of posterior medial femoral metaphysis just lateral to adductor tubercle, with well marginated border and periosteal reaction. Dx? cortical desmoid tumor, aka distal femoral metaphyseal irregularity (DFMI), aka benign cortical irregularity of distal femur, aka periosteal desmoid, aka subperiosteal cortical defect, aka periostitis ossificans. 100% benign. Do not biopsy, do not touch.
Middle aged man with heel pain. X-ray shows calcaneal fracture extending across the posterior tubercle, plus osteoporosis and vascular calcifications. Dx? calcaneal insufficiency avulsion (CIA) fracture related to diabetes. Extremely difficult to treat.
What is the eponymous name for the disease for which the classic triad is high spiking fever, joint pain, and a distinctive salmon-colored rash? Still disease. Seronegative (no antibody spectrum). Serum ferritin is elevated. Clinical Dx.
Young adult with long-term hip and wrist pain. X-rays show carpal ankylosis, normal MCP joints, erosive hip arthritis, hypoplastic iliac wings, and gracile femur. Top Dx? severe juvenile idiopathic arthritis (JIA). Typical adult appearance.
Chronically ill patient with diffuse osteopenia, smudgy trabeculae, and large erosions at multiple joints. Thickened tendons and joint capsules on MR. Low-signal material in joints on all sequences. Top Dx? amyloid deposition. Extremely common in long-term dialysis patients (100% at 20 yrs).
T/F: Most chondroblastomas have clearly visible calcific matrix. False. 75% of chondroblastomas to NOT have any calcific matrix.
Adolescent with epiphyseal mass showing no calcific matrix, portions of lobulated high T2 intensity on MR, marked surrounding marrow edema, and periosteal reaction. Top Dx? chondroblastoma. Lobulated hyperintensity on T2 is typical of benign lesion. Chondroblastomas are well known to cause marked surrounding edema and periosteal reaction. Despite its name, 75% of chondroblastomas to NOT have any chondroid matrix.
Young adult (skeletally mature) with metaphyseal mass showing calcific matrix, portions of lobulated high T2 intensity on MR, no surrounding marrow edema, and no periosteal reaction. Top Dx? enchondroma. Chondroblastoma more typically would have surrounding edema, and would be located in the epiphysis.
Patient of any age with T2-hyperintense enhancing elongated intramuscular mass with feathery pattern within the muscle. Most likely Dx? How would you confirm? hematoma. Feathery pattern and longitudinal orientation are typical. Follow-up MR should show decrease in size and may show change in distribution which confirm hematoma as the diagnosis.
What is little leaguer's shoulder? Chronic Salter I stress fracture of humeral head, seen in young throwers. MR shows high signal periosteal reaction, abnormal high signal in the lateral portion of the physis, and adjacent marrow reactive edema in both the epiphysis and metaphysis.
Young adolescent with shoulder pain related to throwing. X-rays show widening of lateral portion of humeral physis and periosteal reaction. MR shows periosteal reaction, abnormal high signal in lateral physis, and adjacent marrow reactive edema. Top Dx? little leaguer's shoulder, a CHRONIC Salter I rotational stress fracture of the humeral head
Name 5 techniques to reduce artifact from metal in MR imaging. Increase echo train length (fast spin echo is less susceptible than SE, which is less than GRE). Decrease the voxel size (by incr matrix or decr FOV). Increase the receiver band width. Use IR instead of fat sat. Swap phase and frequency directions.
Older child/teenager with increasing chronic leg pain. X-rays show symmetric fusiform tubular cortical thickening in the shafts of the femurs. Top Dx? progressive diaphyseal dysplasia (PDD), aka Engelmann-Camurati disease (ECD). Autosomal dominant inheritance with variable penetration. Conservative treatment.
The pattern of lacy lytic bone lesions in hands and feet is virtually pathognomonic for bony involvement of what disease, especially in the setting of other signs of this disease? sarcoidosis. Consider also enchondroma (often will have chondroid matrix) and tuberous sclerosis (should have other findings typical for this disease).
Normal calcium and phosphate levels in a patient with short 3rd-5th metacarpals and focal soft tissue calcium deposits. What is the diagnosis? pseudopseudohypoparathyroidism
Name the 6 top differential diagnoses for medical lung disease in a newborn. CHIMP+TTN: Cardiac, Hyaline membrane dz (RDS), Immature lung, Meconium aspiration, Pneumonia, and TTN (transient tachypnea of newborn). Meconium asp only in term or post-term infants.
What is a chloroma? aka myeloid sarcoma, aka granulocytic sarcoma, aka extramedullary myeloid tumor, a classically green (Greek "chloros"=green), usually red-blue, solid tumor composed of myeloblasts, an extramedullary manifestation of acute myeloid leukemia.
Of the benign peripheral nerve sheath tumors, which exhibits a "target sign" on MR? Target sign is seen in neurofibromata, rarely in schwannomata. Sign of benignity, differentiating from malignant peripheral nerve sheath tumor (MPNST), which in neurofibroma can result from malignant degeneration, which is extremely rare in schwannoma.
What is the name of the small fibrous band that passes anterior to the PCL from the postior horn of the lateral meniscus to the medial femoral condyle? anterior meniscofemoral ligament (ligament of Humphrey)
What is the name of the small fibrous band that passes posterior to the PCL from the posterior horn of the lateral meniscus to the medial femoral condyle? posterior meniscofemoral ligament (ligament of Wrisberg)
What are the variables examined in a biophysical profile (BPP)? There are 4: fetal breathing, gross body movement, fetal tone, and amniotic fluid. Score 0 or 2 (no "1s") for each for total max of 8. Examined over 30 min, or less if all scores reach 2. Nonstress test (NST) is complementary, based on fetal monitoring.
Fetus with anterior diaphragmatic hernia, supraumbilical gastroschisis, cardiac anomaly, defect of diaphragmatic pericardium, and lower sternal defect, has what named congenital abnormality? pentalogy of Cantrell
US of fetus shows attachment of visceral organs to the placenta with a short or absent umbilical cord has what named anomaly? body stalk anomaly (lethal)
Fetal ultrasound showes extreme, fixed hyperextension of neck with hypoplasia of the inion/occiput, orbits directed upward in "stargazer" orientation, and spinal dysraphism. Top Dx? iniencephaly. Commonly associated with vertebral anomalies, omphalocele, and diaphragmatic hernia.
What is a Hutch diverticulum? CONGENITAL bladder diverticulum, seen in the paraureteral region, less common than the acquired diverticula which occur most often in the setting of bladder outlet obstruction (mostly due to BPH)
You see an ovarian cystic lesion on ultrasound. What 7 entities should you consider in the differential? CHEETAH: Cancer, Hemorrhagic cyst, Ectopic preg, Endometrioma, Teratoma, Abscess, Hydrosalpinx
What is the name for focal fusion across the physis that can occur in children as a complication of Salter fracturs or osteomyelitis? physeal "bar"
Osteomyelitis involving 50% or more of the cortical thickness of a weight-bearing long bone is at risk of what complication? pathologic fracture. This is a "stress riser," increasing stress at this site.
What complication of chronic osteomyelitis can occur in the soft tissue sinus tract 20-40 years after the acute episode? squamous cell carcinoma (classic complication, tends to occur in soft tissues at sinus tract after 20-40 years)
At what time (range) after subarachnoid hemorrhage does vasospasm most frequently occur? 7-10 days after the initial bleed
The long head of the biceps tendon can subluxate under conditions of tears of which structure? tear of superior glenohumeral ligament, coracohumeral ligament, or subscapularis tendon
What is anisotropy in ultrasound? differing echogenicity of soft tissues such as tendons when angle of transducer is changed. Tendon fibers appear hypERechoic (bright) when transducer is PERPENDICULAR to the tendon, but can appear hypOechoic (darker) when transducer is angled obliquely.
What is the Crass maneuver and when is it used? Put the arm behind back, to scan the supraspinatus tendon.
How is the arm positioned for US scan of the biceps long head tendon? palm up, elbow flexed 90 degrees
How is the arm positioned for US scan of the subscapularis tendon? arm rotated externally
On US, a scanned tendon shows normal size or thicker, decreased echogenicity, and loss of normal fibrillar pattern. What is the Dx? tendonosis
In the wrist, where do tendon intersection syndromes most commonly occur? between 1st and 2nd dorsal compartments, and between 2nd and 3rd dorsal compartments
Erosion of ulnar styloid process can occur under condition of tenosynovitis of which tendon? extensor carpi ulnaris
Renal mass in a child less than 10 mo old. Most likely Dx? mesoblastic nephroma (more common than Wilms at this age). Wilms tumor is aka nephroblastoma.
What neoplastic disease is unusual in that its distribution peaks are highest in young boys and older women? multilocular cystic nephroma (presents as cystic mass growing out of the renal sinus)
What congenital renal condition is a well-known precursor to Wilms tumor? Of what embryologic tissue is this a remnant? nephroblastomatosis. Remnant of embryonic metanephric blastema.
What is the "deep sulcus sign" in the knee and what major "white tissue" injury is associated with it? traumatic indentation in the lateral femoral condyle greater than 2 mm, associated with ACL tear
What is a more appropriate name for the so-called "cyclops" lesion? arthrofibrosis
What is a tibial tunnel cyst? Cyst formation in the tibial tunnel, one of several potential complications of ACL reconstruction.
What two findings on mammogram indicate post radiation change? (unilateral) skin thickening and trabecular thickening
What is the yearly recurrence rate for breast cancer? 1% per year
What is the DDx for skin changes in the breast? post surgical/radiation, mastitis, inflammatory breast ca, SVC thrombosis, CHF, lymphoma
On breast US, what is the normal limit for lymph node cortical thickness? 3 mm
What thickness of breast compression is TOO THIN for stereotactic biopsy? 2 cm minimum compression, or stroke margin will be too negative
Atypical ductal hyperplasia shows up in what percentage of all breast biopsies? 0.05
A biopsy of regional amorphous microcalcifications most recently results in what histopathologic entity? atypical ductal hyperplasia (ADH)
What number of lesions in each breast is required to call “multiple bilateral partially obscured masses,” and give a BI-RADS 2? two on one side, one on the other (or more)
T/F: All discordant biopsy results must go to excisional biopsy. T (if truely discordant; if you just missed the calcs and no calcs were seen on core specimen radiographs, then just re-core)
Amorphous or coarse heterogeneous calcifications are given what BI-RADS category? BI-RADS 4. These are INDETERMINATE descriptors, NOT benign. Must biopsy.
What % of DCIS shows up as calcs? 0.9
T/F: Papilloma can show up as calcs on mammogram. False. These are intraductal masses that do not calcify.
What constitutes a worrisome (not categorically benign) breast nipple discharge? Spontaneous clear or bloody discharge.
Diagnostic mammography and ultrasound reveal a single dilated duct in both breasts. What is the BI-RADS category? BI-RADS 2, benign. Worry only if unilateral.
T/F: Any mass with encapsulated fat is benign and should not undergo ultrasound or biopsy. True. Lipoma, hamartoma, and galactocele can all have this appearance. All are benign.
Step-ladder sign on breast ultrasound is a sign of what condition? Intracapsular silicon implant rupture
Baseline mammogram with punctate round segmentally distributed calcs. What is the appropriate BI-RADS category? BI-RADS 3. F/U in 6 months.
Baseline exam with well circumscribed mass (more than 75% of margins), nothing on ultrasound. What is the appropriate BI-RADS category? BI-RADS 3. F/U in 6 months to assure stable size.
BI-RADS 4 breast mass resulting in PASH on pathology (concordant) requires what kind of followup? annual screening
T/F: Complex sclerosing lesions (such as radial scar) is typically related to prior trauma or surgery. False, not related to prior trauma or surgery. "Dark star" lesion on mammogram.
"Dark star" lesion on mammogram resulting in radial scar should undergo what management? Excisional biopsy to exclude tubular carcinoma or atypical hyperplasia, which are seen in a small but significant percentage (?10%?).
Why is it normal to see fat layering "inferiorly" on MR of a galactocele? Breast MR is performed in the prone position, but images are evaluated in typical anatomical position (supine).
Name 5 causes of non-immune hydrops fetalis. Fe-def anemia, SVT CHF, tw-tw txfusn syndr (mono) CHF in recip, Turner (45X), teratoma, beta-glucuronidase def(mucopolysacch VII, aka Sly), maternal DM/hyperthyr/parvovir B19 (fifth dz)/CMV/syphilis, thalassemia subset, Niemann-Pick C, and Gaucher 2.
What is the DDx for a rim-enhancing breast mass? cancer, postop seroma, fat necrosis, inflamed cyst, (NOT lymph node). Abscess can also be rim enhancing.
Name 5 indications for breast MR. high risk screening, new cancer staging, response to therapy, axillary metastasis with unknown primary, problem solving (not a great last indication, avoid), implant integrity (noncon)
T/F: “Scar” showing enhancement on MR is still likely benign and can be given a BI-RADS 2. False. Enhancement is suspicious. Biopsy.
What drug can be given to reduce background breast parenchymal enhancement? Tamoxifen (improves visibility of masked lesions)
T/F: High background parenchymal enhancement on MR is typically seen in patients with mammographically dense breasts. False. Breast background parenchymal enhancement on MR does NOT correlate with breast density on mammogram.
When is the optimal timeframe for performing breast MR in premenopausal women? 7-14 days after first day of menstruation.
Define a focus vs mass vs non-mass enhancement on MR using the BI-RADS lexicon. Mass is a 3D space occupying lesion >=5 mm. Focus is less than 5 mm. If not a 3D space occupying lesion, then call “non-mass enhancement.”
What are the accepted BI-RADS descriptors for mass SHAPE and MARGIN on MR (name 3 for each)? Shape: round, oval, or irregular (lobulated is still used but phasing out). Must be oval to be benign (or round: maybe). Margins: Smooth, spiculated, or irregular. Only smooth is benign.
What are the accepted BI-RADS descriptors for enhancement pattern on MR? homogeneous, heterogeneous, dark internal septations, rim enhancement, enhancing internal septations, central enhancement. Dark internal septation is used to describe fibroadenomas (benign). Homogeneous connotes benignity. All others are suspicious.
T/F: A probable lymph node with normal size and morphology but rapid enhancement and washout kinetics is worrisome for malignancy and should be sampled. False. Lymph nodes normally have rapid enhancement and washout kinetics. Base evaluation on morphology.
What did the DMIST trial reveal about the difference between digital and screen film mammography for the general population? Was there a subgroup that did show a difference? No difference between digital and film screen technique for general population. But, for women who were younger than 50, premenopausal, or had dense breasts, there was improved detection on DIGITAL mammography over screen film.
Hyperintense lesions on STIR sequence breast MR are benign with one exception. What cancer is hyperintense on STIR? Mucinous breast cancer.
How does enhancement kinetic come into play for evaluation of possible fat necrosis? Not a factor. Fat necrosis can have any kind of enhancement kinetics. Diagnosis is based on presence of encapsulated fat. Even a dot of fat can be enough to call benign, BIRADS 2 (provided there are no worrisome findings).
When is a rim-enhancing lesion on breast MR reasonably diagnosed as an “inflamed cyst?” Only call a smoothly marginated rim-enhancing lesion an inflamed cyst in the presence of other noninflamed cysts with clearly benign morphology. A lone rim-enhancing lesion is worrisome.
You have a patient with an irregular hypoechoic antiparallel mass on US: DDx? Cancer, abscess. Cancer must be excluded. If clinically inflamed and abscess makes sense, then course of Abx is reasonable. If lesion does not COMPLETELY resolve, then biopsy is recommended.
T/F: A lesion with benign morphology and internal enhancing septations is almost always benign, BI-RADS 2. False. Internal enhancing septations makes a lesion worrisome for cancer.
T/F: In breast MR, morphology always trumps kinetics. True. For instance, invasive ductal carcinoma (IDC) can have benign kinetics, but should have worrisome morphology.
What are the accepted pattern and distribution descriptors for non-mass enhancement (NME)? Pattern: homogenous, heterogeneous, stippled, clumped, reticular. Only stippled implies benign. Distribution: focal, linear, ductal, segmental, regional, multiple regions, diffuse.
What pathology is most associated with “clumped”-pattern non-mass enhancement? DCIS, esp if “clumped” NME has a linear, ductal, or segmental distribution.
What is the quantitative (%) delimiter for “plateau” enhancement in breast MR enhancement kinetics? 10% change from the first (90-sec or 2 min) post-contrast scan. Less than 10% = washout. More than 10% = persistent enhancement.
What is the quantitative (%) delimiter for “rapid” enhancement in breast MR enhancement kinetics? more than 100% increase from baseline signal at the first (90-sec or 2 min) post-contrast scan. Medium enhancement is a 50-100% increase in signal. Slow is <50% increase.
T/F: Pectoralis muscle invasion upgrades tumor staging of breast cancer. False. Muscle invasion changes surgical management but does not equate to chest wall invasion (which does upgrade stage). Tumor must invade THROUGH the pectoralis and into deeper structures to call chest wall invasion.
T/F: Tumor abutting pectoralis muscle by 2 cm on breast MR indicates muscle invasion. False. Muscle invasion requires muscle enhancement. Does not affect staging, but does change management at surgery.
A screening MR finding results in US guided biopsy, which comes back benign on pathology. What is the appropriate management at this point? F/U in 6 months to make sure site of MR abnormality was appropriately sampled.
Name 5-8 indications for MR staging of a newly dx breast cancer. extent of dz, ipsilateral or contralat dz, axillary or internal mammary nodes, chest wall involvment for large posterior tumors, invasive lobular carcinoma, Paget dz, positive or close lumpectomy margins, patients considered for partial breast irradiation
T/F: Changes in background parenchymal enhancement on MR are worrisome for invasive lobular carcinoma. False. background parenchymal enhancement is hormonally affected and can change over the course of menstrual cycle in any normal patient.
T/F: Any patient with pathology showing atypia on breast biopsy should be sent for excisional biopsy. True. There is upgrade to IDC in 25% of cases upon excisional biopsy.
T/F: Any patient with discordant results on breast biopsy should be sent for excisional biopsy. True. Send to surgery. Do not just follow up with imaging. Do not re-biopsy (re-core) unless calcs were missed (in which case this is not discordant, but a missed biopsy; try again).
T/F: There are specific features on ductogram and ultrasound that distinguish between papilloma and papillary carcinoma. False. This cannot be distinguished on ductogram. Core biopsy is recommended.
Oval smoothly marginated (or macrolobulated) 2-cm mass on MR with homogeneously bright STIR signal on MR (with or without dark internal septation) and benign washout kinetics. Top Dx? How sure are you? fibroadenoma. Diagnosis is secure with these specific features.
What congenital disease is associated with fetal rhabdomyomas? tuberous sclerosis
What is a velamentous cord insertion? abnormal insertion of umbilical cord into choriamniotic membranes, then traveling between amnion and chorion to placenta, not protected by Wharton's jelly. Vasa previa if near cervical os, high risk for rupture during labor. C-section.
US at 2nd trimester shows abnormal insertion of umbilical cord into the fetal membranes (choriamniotic membranes), then travels between the amnion and the chorion to the placenta. What is the name for this abnormality? What if near the cervical os? velamentous cord insertion; vasa previa if near cervical os, high risk for rupture during labor. C-section.
What are the 4 known increased risk factors for heterotopic pregnancy? “Redo-ME, IUD, PID, and EndoME”: assisted reproduction (up to 1:100 incidence in this population), intrauterine contraceptive device, and a history of pelvic inflammatory disease or endometriosis.
What is the difference between Hashimoto thyroiditis and De Quervain's thyroiditis? De Quervain's thyroiditis (aka subacute thyroiditis) is painful, often viral with fever and WBC, usually more focal within the gland. Hashimoto thyroiditis is painless, silent, autoimmune, more often diffuse, and much more common.
What critical neoplastic concern should be evaluated on any US on a patient with Hashimoto thyroiditis? thyroid non-Hodgkin lymphoma, presenting as focal hypoechoic bulging in the setting of a diffusely hypoechoic, lacy, hypervascular (acutely) gland and biochemical evidence of Hashimoto disease
What is the cause of the “zebra-like” banding resembling magnetic field lines in MR images? On what sequences is this artifact seen? phase aliasing; this pattern is seen on T2* weighted gradient echo sequences, not on spin-echo sequences.
What can one do to decrease Gibbs artifact on MR images? Gibbs artifact, aka ringing artifact, aka truncation artifact, can be reduced by increasing the sampling rate, which can be done by increasing the matrix size or decreasing the field of view (although reducing FOV can cause phase wrap from aliasing).
What can be done to reduce chemical shift artifact in MR imaging? Repeat the sequence increasing the receiver bandwidth. This will reduce the thickness of chemical shift artifact.
Describe the difference in appearance between Type 1 and Type 2 chemical shift artifact. Type 1: shift occurs only along frequency-encoding direction, with bright and dark bands at the interfaces between fatty and watery tissues. Type 2: “India ink”, outlines boundaries of tissues with large differences in fat/water content.
An MR scan has a lot of parallel lines throughout the images. What is this and how do you get rid if it? k-space spike, usually from noise. Re-scan usually takes care of it.
What is the cause of ill-defined decreased MR signal intensity in the deep portions of the body in an obese patient? How can you get rid of it? Dialectric effect, caused by variations in tissue conductivity, more prominent on higher field strength scanners (e.g., 3T). There is no great way to reduce this, but routine use of dielectric pads on the patient somewhat premeditates this artifact.
Roughly, what is the binding energy (ionization threshold energy) of a water molecule? around 13 eV for outer shell electrons. Note that this is on the order of 10,000 less than the photon energies used on CXR (120 kVp), CT (100 kVp), and nuclear medicine (140 keV).
What is the equation for probability of photoelectric absorption? Z cubed over E cubed. (Z^3)/(E^3) Z = atomic number,
Doubling the keV of an incident gamma photon on a material does what to the probability of photoelectric absorbption? Decreases by factor of 8 (2 to the 3rd power). Remember the equation for probability of photoelectric absorption: (Z^3)/(E^3).
Doubling the Z of a material does what to the probability of photoelectric absorption of an incident gamma photon? Increases by factor of 8 (2 to the 3rd power). Remember the equation for probability of photoelectric absorption: (Z^3)/(E^3).
What is the basic underlying technique (spin echo vs gradient echo) for black blood MR images in MR? bright blood? Black blood = spin-echo (think typical flow voids). Bright blood images are acquired using gradient echo technique, in which moving blood is “fresh” relative to the stationary tissue which is saturated by repeated application of RF pulses.
T/F: Digital image compression ratios of more than 3:1 are possible without loss of information. False. Compression ratios of no more than 2:1 or 3:1 are possible without loss of information.
What is the broadly shared machine language protocol that allows communication among systems across the entire internet? TCP/IP (Transmission Control Protocol / Internet Protocol). It’s what holds the internet together.
T/F: HL7 and DICOM are application layer standards. True.
Name a test pattern that can be used to evaluate effects of monitor brightness and illumination (lux) levels on contrast resolution. SMPTE pattern (Society of Motion Picture and Television Engineers Test Pattern)
What does IHE stand for and what is it? Integrating the Healthcare Enterprise (IHE) is an initiative to improve sharing and digital communication across healthcare systems such as DICOM, HL7, RIS, EMR, EHR, etc.
Which have better quantum efficiencies: photomultiplier tubes or photodiodes? Photodiodes have much better quantum efficiencies than PMTs.
How many binary configurations can a 7 bit “word” have? What integers can be represented? 128 configurations (2^N), representing integers 0-127. N bits can represent integers 0-(2^N-1) due to 0 being represented by one of the configurations.
What are the 4 possible values for individual organ effective dose weighting factors (w-sub-T) according to the 2007 ICRP recommendations (Publication 103)? .12, .08, .04, and .01| .12 = Red marrow, Colon, Lung, Stomach, Breast, Remainder tissues| .08 = Gonads| .04 = Bladder, Esophagus, Liver, Thyroid| .01 = Bone surface, Brain, Salivary glands, Skin| Total Effective Dose= Σ wT
For technetium generators, what is the NRC limit for molybdenum-99 breakthrough? No more than 0.15 microCi of Mo-99 per mCi of Tc-99m
Why is the signal to noise ratio of a post-contrast subtraction MR image much higher than the SNR of either the baseline noncom or the postcontrast image? SNR is proportional to standard dev, so follows addition and subtraction in quadrature; SNR of the difference image is the square root of the sum of the squares of the SNRs of the two acquired images. When the magnitudes are similar, noise is compounded.
What is the wavelength of a 10 MHz ultrasound pulse in tissue? 0.154 mm. Divide 1.54 mm per microsecond (average speed of sound in tissue) by 10 MHz, which is equal to 10x10^6 cycles per second, which is equal to 10 cycles per microsecond.
What is specular reflection? Is it an artifact? It is not an artifact but a normal property of ultrasound waves incident on any long smooth surface. Echo strength from a specular reflector is highly angular dependent. Incident and reflection angles are equal.
Specular reflection is a property of ultrasound waves incident on a long smooth surface with equal incident and reflection angles, echo strength highly angular dependent. What is the other kind of reflection in ultrasound? Diffuse reflection makes up most of the ultrasound image and occurs when incident ultrasound wave pulse reflects from interrupted or irregular surface such as stones, with strength NOT angular dependent, low surface detail due to interference.
Other than angle, what determines the strength of ultrasound echoes? Absolute difference in impedance (measured in “rayls” – liver has impedance = 1.65E6 rayls, c/t muscle = 1.71E6 rayls, lung = 0.18E6 rayls, air = 0.0004E6 rayls, bone = 7.8E6 rayls). E6=x10^6
How is ultrasound reflection quantified? For any interface between tissue a and tissue b with impedances Za and Zb, respectively, reflection coefficient (R^2) = [(Za-Zb)^2]/(Za+Zb). Square the difference and divide by sum. R^2 is the fraction of sound that is reflected.
T/F: Ultrasound beam attenuation is exponentially dependent on frequency. False. The frequency dependence is linear so an attenuation of 2 dB/cm at 1 MHz increases to 12 dB/cm at 6 MHz.
Describe the “range equation” for determining depth at which the echo signal is formed in ultrasound. Depth (D) is related to time (t) between pulse emission and echo reception and speed (c) of sound propagation by the range equation: D=ct/2. Divide by 2 to account for both directions. Average speed of sound in tissue is 1540 m/s, or 1.54 mm/microsec.
In ultrasound, what do the B, M, and A stand for in “B mode,” “M mode,” and “A mode” displays, respectively? B for “Brightness” mode. M for “Motion” mode. A for “Amplitude” mode (no longer used).
What is the typical ultrasound pulse duration time? What about pulse repetition period? Pulse duration time is usually 1-2 microsecond or less. Pulse repetition period is on the order of 50-200 microseconds. Pulse repetition frequency is on the order of 5-20 kHz.
Define near field and far field in ultrasound imaging. Near field = Fresnel zone, the acoustic field before the focal zone. Far field = Fraunhofer zone, the acoustic field beyond the focal zone.
In discussing gamma camera efficiency, what is the relationship between intrinsic and collimator efficiency? System efficiency is the product of intrinsic and collimator efficiency. This is in contrast to system resolution, which is the quadratic sum of intrinsic and collimator resolution (they are added in quadrature; iow, the sqrt of the sum of squares).
In ultrasound, what determines frame rate? Maximum frame rate (FRmax) is determined by pulse repetition frequency (PRF, which remember is affected by max scanning depth) divided by the product of the number of scan lines (N) and the number of focal zones (n). FRmax=PRF/Nn
Name the 3 dimensions of resolution in ultrasound. axial resolution (in depth direction, increased with shorter pulse duration), lateral resolution (affected by line density, beam width, and relation to the focal zone), and elevational resolution (slice thickness, affected by fixed or active focusing)
What are the 4 operator-controlled parameters that affect ultrasound image pixel intensity? pulse power, master gain, time-gain-compensation (aka depth-gain-compensation), and monitor brightness
In nuclear SPECT imaging, what kind of artifact is caused by nonuniformity in the gamma camera? ring artifact
In nuclear SPECT imaging, what causes ring artifact concentric with the image center? What causes this type of ring artifact in transmission CT? What about noncentered ring artifacts in SPECT? gamma camera nonuniformity in SPECT (unbalanced detector in CT). Noncentered ring artifact (usually seen as a blur rather than a ring) is caused by Center of Rotation (CoR) error, and can be corrected systematically.
What type of phantom is most often used to evaluate overall SPECT imaging performance? Jasczak phantom
In ultrasound, magnification can be achieved with 2 types of zoom. What are they and what is the difference? write zoom and read zoom. Write zoom is analogous to optical zoom in photography; the magnified image is acquired proactively, focused only on the zoomed field of interest. Read zoom is analogous to digital zoom in photography.
If the positron emission activity in a patient is doubled, what is the effect on random coincidence events in the PET scan? Random coincidences are quadroupled when the activity in the patient is doubled. Based on R=2 x (timing window) x (detector 1 count rate) x (detector 2 count rate), and fact that both count rates proportional to patient activity.
What is the ACR-recommended minimum frequency of QC testing of ultrasound equipment? semi-annual (twice a year)
What is area of an x-ray field has the highest resolution? Why? The anode side of the x-ray field has the highest resolution, due to foreshortening of the effective focal spot.
What are the limits for acceptable variation from baseline in ultrasound horizontal and vertical resolution? 2 mm or 2% for vertical distance accuracy, and 3 mm or 3% for horizontal distance accuracy. Variation from baseline outside these levels is considered to be unacceptable.
In ultrasound, what is the maximum allowable ring-down or dead zone? Less than 3 mm at 7 MHz and above. This is the zone where echoes are not seen and lesions can be missed. Rarely seen in systems these days due to improved technology.
At what photon energy are the probabilities of Compton scatter and photoelectric effect equal in tissue? Roughly 26 keV. In mammography, the dominant cause of attenuation is photoelectric effect (mean keV on the order of 20????). In CXR, the dominant cause of attenuation is Compton scatter.
What is grid ratio and how does photon attenuation relate? Grid ratio= thickness of the grid / interspace diameter. Higher ratio results in more photon attenuation.
What is a typical focus for a grid? 100 cm usually (or 183 cm for CXR).
In ultrasound, what are the two limiting factors that determine the maximum pulse repetition frequency? speed of sound propagation (c) and maximum depth of field of view (D). The maximum pulse repetition period is PRF=c/2D. Note that this is similar to the range equation, D=ct/2, also written as 2D/c=t.
What property of sound traveling through an interface between two mediums determines its refraction? What is the equation that explains refraction angles? Ratio of speed of sound in each medium determines refraction in accordance with Snell’s Law. Sin(θi) / Sin(θt) = Speed in incidence medium / Speed in refracted medium, where Sin(θi) and Sin(θt) are the angles of incidence and transmission, respectively.
What is the equation for ultrasound attenuation? Attenuation (dB) = (µ) (f) (x), where µ is the attenuation coefficient (in decibels per centimeter per MHz), f is the ultrasound frequency in MHz, and x is the tissue thickness in cm. Typical (µ) values for tissue are 0.5-1.0.
How is the Doppler ultrasound image made, comparing to gray-scale? Doppler US uses the frequency shift of the returning echoes (from blood cells, debris, turbulence, etc) to form an image while gray-scale imaging uses the amplitude of returning sound waves. Both use the elapsed time to determine depth. Ref: RSNA modules.
What is the equation that explains Doppler shift and its relation to blood flow velocity? ?CONFIRM? velocity (V) = (Fd)(c) / 2(Ft)cos(θ), where (Fd)=Doppler frequency SHIFT, (c)=speed of sound in tissue, (Ft)=transmitted frequency, and (θ)= Doppler angle between direction of blood flow and direction of transmitted sound wave. cos(60)=0.5. cos(90)=0.
How is Doppler made audible in ultrasound imaging? After demodulation to extract Doppler frequency (low) from transducer frequency (high), the Doppler frequency shift (Fd) is sent to the audio amplifier. Doppler shift range for diagnostic ultrasound is in the audible frequency range (15-20,000 Hz).
Name the two types of Doppler imaging in ultrasound. Pulsed Wave (Spectral) Doppler (the wave form, needing a gate placed in the desired sampling location), and Color Doppler (aka Duplex).
What causes aliasing in Doppler ultrasound? What is adjusted to reduce aliasing? Aliasing occurs when Doppler shift is higher than Nyquist frequency (kHz), which is half of the pulse repetition frequency (PRF). Adjust PRF (which adjusts scale on Pulsed Doppler), choose a Doppler angle further from 0° (to decrease Doppler shift).
What artifact can be reduced by reducing the gain on color Doppler imaging? Color bleed. Not aliasing, which requires adjustment of PRF.
In ultrasound Pulsed Wave (Spectral) Doppler imaging, what is the preferred Doppler angle? Why? 30-60degr. >60degr, measured shift is small, low signal; angle inaccuracy magnifies velocity errors. Near 90degr, may show false occlusion or mirror image ambiguity. @Doppler angle <20degr, refraction causes loss of signal and aliasing becomes an issue.
What are the NCRP recommendations for when a risk-benefit analysis should be made regarding the use of ultrasound? In accordance with ALARA, NCRP recommends risk-benefit analysis when the Thermal Index exceeds 1.0 or the Mechanical Index exceeds 0.5. Usually in context of Doppler imaging of a fetus.
T/F: Power Doppler ultrasound Mechanical Index (MI) values of 30 kpa can result in cavitation in ultrasound. False. MI amplitudes of less than 0.3 Mpa (megapascal), or 300 kpa, result in minimal to no non-thermal damage.
What are the two values defined by ultrasound pulses that relate to likelihood of mechanical or thermal damage? spatial peak and temporal average (SPTA) of the beam. The peak intensity is measured at the peak pressure amplitude of the beam, and the temporal average is measured and averaged across the beam.
What is the equation and unit for relative intensity in ultrasound (and all sound for that matter)? Relative intensity (dB)=10 x log(I1/I2), where I1 and I2 are the reference and measured intensities. Each 10 dB corresponds to an order of magnitude (10x) difference. Intensity is is measured in mW/cm2 and proportional to pressure squared.
T/F: In a phased array ultrasound transducer, several (but not all) of the crystals are activated during each pulse. False. This would still be called a linear array transducer (with beam shaping). In a phased array transducer, all of the crystals are active (at variable times that determine beam steering) during each pulse.
What is the AIUM threshold for potential bioeffects in ultrasound? AIUM established threshold level for potential bioeffects in diagnostic ultrasound is set at 100 mW/cm2 spatial-peak temporal-average intensity, which if exceeded could lead to potential bioeffects.
What is HIFU? High Intensity Focused Ultrasound (HIFU) is therapeutic ultrasound, not diagnostic. Experimental animal studies have achieved 5,000-20,000 mW/cm2, much higher than the AIUM threshold of 100 mW/cm2 for diagnostic US.
What is Q factor and how does it relate to spatial frequency in ultrasound? Q factor = center operating frequency / bandwidth. Determines spatial pulse length (SPL) and resolution. Low Q corresponds to short SPL, increased AXIAL spatial resolution, and wide bandwidth, not good for Doppler. "Low Q, Hi Res"
T/F: Spatial compounding reduces frame acquisition time and increases frame rate. False. Spatial compounding requires repeat insonations and receptions, resulting in a slower frame rate.
One half-value-layer in ultrasound corresponds to what relative intensity in dB? -3 dB, based on equation: Relative intensity (dB) = 10log (I1/I2), where I1 and I2 are the reference (starting) and measured (ending) intensities, which in this case is 0.5. The base 10 log of 0.5 is -0.301. Multiply by 10 for dB.
What is the most common piezoelectric crystal material in ultrasound? PZT: lead zirconate titanate
What governs the center frequency of an US probe? Thickness of the transducer PZT elements. Twice the PZT element thickness is the wavelength of the resonance frequency at the speed of sound within the crystal element, which is the center frequency.
T/F: Power Doppler energies deposited in the tissue are much higher and more potentially damaging than those used in Pulsed Wave Doppler and Color Doppler. False. Power Doppler energies are no greater than Color or Pulsed Spectral Wave Doppler.
What is “duty factor” in the context of ultrasound imaging? Described as a percentage, duty factor is the ultrasound pulse duration relative to the pulse receive duration.
What is the artifactual dark region 1-3 mm deep to the ultrasound probe on older systems? (Newer systems have greatly overcome this artifact.) Ring down or dead time artifact. Ring down time or dead time is time for pulsed crystal ring to dissipate and transmit-receive switch to complete to allow receipt of echoes.
T/F: In contrast enhanced MR, the contrast agent causes increased echo signals upon RF excitation and is directly imaged. False. It is the effect that the magnetic properties of the contrast agent has on the tissue T1 relaxation times that is imaged (or T2 in case of negative contrast agents). Protons are still the source of signal. The agent is not directly imaged.
Relaxation agents, shift agents, chemical shift agents, and frequency agents. What are these in terms of MR contrast agents? Positive MR contrast agents (relaxation agents like gad) shorten T1 relaxation times. Negative contrast agents (shift, chemical shift, or frequency agents) produce local field inhomogeneities resulting in loss of phase coherence and shorter T2 times.
What are the amniotic fluid measurements that constitute eu-, oligo-, and polyhydramnios? What is the normal value for AFI? Euhydramnios is 2-8 cm deepest fluid pocket. Below this is oligohydramnios, and above this is polyhydramnios. Normal amniotic fluid index (AFI) values are 5-24.
A 20-wk fetal US reveals twins separated by faint visible membranes with a “peak” sign. One twin has well formed lower extremities but malformed head, chest, and no upper extremities, with pulsatile flow in the umbilical veins. The other twin is NL. Dx? Twin Reversed Arterial Perfusion (TRAP) syndrome, aka acardiac or parabiotic twin. Intervention (usually with laser embolization of vascular connections) is necessary to avoid complications in the normal twin.
What three organ systems must be especially closely evaluated in the surviving twin fetus in cases of single twin demise and signs of monochorionicity? If there are signs of ischemic injury in the surviving twin, what is this condition called? Brain, kidneys, and bowel should be evaluated for signs of ischemic injury, to exclude twin embolization.
What effect does albumin binding have on Gd-DTPA based contrast agents? Enhanced relaxivity (T1 shortening) has occurs when binding Gd-DTPA to serum albumin.
What is Teslascan? mangafodipir trisodium, made of paramagnetic manganese ion and the chelating agent fodipir. 7.25% molecular manganese content. Positive MR contrast agent. Shortens T1 time of targeted issues. Approved for liver and pancreas tumor imaging.
What MR contrast agent has weak and transient interactions with serum proteins that causes slowing in the molecular tumbling dynamics, resulting in strong increases in relaxivity and enhanced tissue T1 shortening? gadobenate dimeglumine (MultiHance). Do not confuse this effect with protein “binding.” There is no appreciable binding of gadobenate ion to human serum proteins that would cause a difference in serum clearance.
Which contrast agent has the lowest reported incidence of NSF? ProHance (a macrocyclical chelator). Some say no reported cases, but BRACCO has acknowledged at least one case of NSF after only-Prohance administration (6 mo after last of 6 injections over 2 years). But ProHance still has the lowest reported incidence.
What is the dominant interaction responsible for attenuation in X-ray and CT modalities other than mammography? What is it for mammography? Compton scatter dominates, except for mammography where photoelectric effect (due to much lower kV used (molybdenum target).
The attenuation of x-rays is most closely related to which of the following?: atomic number (Z), mass number (A), physical density (g/cm2), electron density, calcium content, water content, fat content, or proton density? electron density (which correlates with Z but is not synonymous)
To decrease the noise in any image image by half, what must be done to the signal (or dose, or counts, etc)? Quadruple the signal to half the noise. Noise in signal N is proportional to standard deviation (sigma), which is estimated at sqrt(N).
What kind of MR contrast agent is SPIO? How does it work? What cells take it up? What is the effect on T1? T2? Effect on tissues? Vessels? SuperParamagnetic Iron Oxides (ferumoxides, Feridex®) are taken up by reticuloendothelial cells, which metastatic lesions lack. Liver, spleen, and LNs are dark, but intravascular particles cause T1 shortening (vessels are bright on T1), no effect on T2.
What is ferumoxtran-10? ultrasmall superparamagnetic iron oxide (USPIO) (Sinerem®, Combidex®, Clariscan™), taken up by macrophages in lymph nodes, used to differentiate benign lymph nodes (dark on T2*) from metastatic nodes which maintain a bright spot (bad)
Name 3 commonly used radiopharmaceuticals with a roughly 3-day half-life. What are the precise half-lives in hours? What are the critical organs? Ga-67 (78 hrs, lower large intestine), In-111 (67 hrs; Octreotide and WBC: spleen), Tl-201 (73.1 hrs; testes, thyroid).
What is the half life of tPA (alteplase)? 5 minutes
What is the half-life of Coumadin? How long should the patient be off Coumadin before IR procedures? 2 days half life. 5 days off.
What is the half-life of heparin? How long should the patient be off heparin drip before IR procedure? 1 hour
How long can a triple lumen central line be left in place? 7-10 days
What is the measurement most relevant to MRI safety regarding radiofrequency effects? What are the units? Specific Absorption Rate (SAR) is the measure of the rate of energy deposition (power) divided by tissue mass in units of watts/kg.
What is the pressure limit for intussusception reduction? 120 mm Hg (measured by manometer)
What is the name for the abnormal bone that occurs in patients with Sprengel deformity? What bone disease is associated with this deformity? omo-vertebral bone. Klippel-Feil syndrome.
How does SAR change in relation to magnetic field strength? Radiofrequency SAR increases with the square of the magnetic field strength.
How does SAR change in relation to flip angle? Radiofrequency SAR increases with the square of the flip angle. Fast (ETL) sequences have lower flip angle (typically 10-40 degrees), but usually have short repetition time (TR), which increases power deposition.
How does SAR change in relation to repetition time? Radiofrequency SAR increases inversely proportional to repetition time (TR). Lengthening TR reduces energy deposition per unit time (power) in a linear fashion.
Created by: dudall