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Neuro Radiology
Neurology
| Question | Answer |
|---|---|
| MRI: T1/T2 | T1: fat bright (water dark); T2: water bright (fat dark) |
| Spinal cord abnormalities: imaging | usually MRI (if CI: myelogram) |
| Nuclear imaging: indications | Blood Flow; Brain Activity (Alz dz, Parkinson, Epilepsy); suspected brain death; mets |
| quadrigeminal cistern appearance on imaging: | should smile |
| suprasellar cistern appearance (if healthy): | resembles a star |
| Trauma/Bleeds: imaging of choice | noncontrast CT |
| Head trauma: 5 questions | Is middle of brain in middle of head? Symmetry? Suprasellar cistern = star? 4th ventricle midline & symmetric? Lateral ventricle effaced? |
| Lucid interval seen in what trauma? | epidural hematoma |
| epidural hematoma: appearance on CT | lenticular (biconvex) |
| subdural hematoma: blood source | usually venous (bridging veins in space) |
| subdural hematoma: etiology | Acceleration/ Deceleration injury; Veins transversing subdural space |
| subdural hematoma: appearance on CT | Cross suture lines and extends over larger area; Crescent shaped |
| SAH: etiology | Trauma, Drugs, or Ruptured Aneurysm. Sx: thunderclap/ worst HA of my life |
| SAH: appearance on CT | Linear, within cisterns and sulci; bleed follows outlines of the gyri |
| Le Fort I: | Floating palate, fx maxillary sinus |
| Le Fort II: | Pyramidal fx, medial orbital and lateral maxilla |
| Le Fort III: | Craniofacial disjunction, horizontal orbits |
| Orbital blowout fx | comminuted floor fx: herniated orbital contents; inf rectus mx entrap or vert diplopia d/t edema; blood in max sinus when orbital trauma |
| Nasal bone fx | prob not need CT, but need look in nose |
| Spine x-ray: 5 lines | Prevertebral ST: should be thin. Anterior & posterior vert lines: should be aligned vertically. Spinolaminar line: join spinous process & lamina: should be aligned vertically. Ensure none of spinous processes are fractured. Check facet joints |
| Spondylolisthesis: look also for: | facet fx |
| Normal disk on MRI: | low T1 signal, High T2 (nuc pulposus is mostly water); normal disks do not extend past margin of vert |
| Degenerative disk on MRI: | dehydrates: decreased T2; loses height |
| Spinal cord lesion types: | Demyelination; Cysts; Infarction; Tumor |
| Demyelination on MRI | patchy T2 signal; may be d/t: MS; Post infectious Myelitis; Compressive Myelopathy; Post Radiation |
| Spinal cord infarction on MRI | Gray Matter Affected Preferentially: H-pattern high T2 signal |
| Spinal cord tumors may be: | Ependymomas; Astrocytomas; Hemangioblastomas; Mets |
| CVA | 3d leading COD; 75% infarction, 25% hemorrhage; cell death; Na pump fail; Na influx; cytotoxic edema; gray matter usu gets more blood, suffers more w/infarct; |
| Edema on MRI | T1: dark; T2: bright |
| Purpose of CT in CVA | Not dx; only to r/o other conditions that would CI some tx (tumor, bleed) |
| 2/3 of all cerebral infarcts are: | MCA stroke |
| CVA on CT | Hyperdense Artery Sign; Loss of grey; CT normal up to 12 hours post; insula ribbon sign: blurring of gray-white junction |
| Brain neoplasm: imaging of choice | MRI |
| Brain neoplasm: presentation | Increased ICP (HA, Seizure, Neuro Deficit); Hydrocephalus (HA, N/V, Papilledema) |
| Brain neoplasm: Extra-axial: | Meninges, Ventricles, Skull |
| Brain neoplasm: Intra-axial: | Brain parenchyma |
| Astrocytoma | Glial tumors: 40-50% of CNS Neoplasms |
| Astrocytoma: Grade IV | GBM (45-55 yo); necrosis/ hemorrhage, edema, ring enhancement |
| Meningioma | 50-60 yo; may increase in PG; various grades (90% benign) |
| Brain neoplasm: mets | 1/3 of all intracranial neoplasms; lung, breast, melanoma, colon, lymphoma, prostate |
| Brain neoplasm: imaging | Gray-White matter junction; Marked Edema; Can be multiple, bilateral |
| Brain neoplasm: most common site for kids (unlike adults) | posterior fossa (medulloblastoma) |
| Head & Neck ca | SCCA; older, smoker OR younger, HPV-associated |
| Acute sinusitis | imaging not needed (but show air-fluid levels or complete opacification; H flu, SP, or M Cat (kids) |
| Chronic sinusitis: imaging: | not needed; shows mucosal thickening, wall indistinctness |
| Croup | laryngotracheitis/ bronchitis; barking seal cough, fever, hoarse; steeple sign on imaging |
| Epiglottitis | Acute fever, dysphagia, stridor, sniffing position, resp fail; formerly H flu, now SP; Imaging: Thumb print sign |
| AIDS-related CNS infxn: imaging of choice | MRI; 2/3 develop CNS infxn |
| MS imaging | MR sensitive, but not diagnostic; Periventricular T2 bright signal: inflammation |
| NPH | Chronic hydrocephalus; Sx: incontinence, gait abnormalities, dementia; CT: Ventriculomegaly out of proportion to sulcal prominence |
| Imaging findings assoc w/ 4 stages of brain abscess evolution | early cerebritis (swollen/edema; high T2); late cerebritis (inc central necrosis; vasogenic edema at edges); early capsule; late capsule (well define ring) |
| Meningioma: imaging | Often Along Brain Surface; Hyperdense, Homogeneous Enhancement |
| Lacunar infarct: if R upper extremity deficit = | Lesion is at subthalamic nucleus on left |
| Cerebral aneurysm imaging of choice | Angiography is definitive. CT / MRI may not be thorough enough for smaller |
| ICH / SAH imaging of choice | Noncontrast CT > MRI. Avoid LP. |
| MRI for CVA: | Diffusion weighted is more sensitive thatn nondiffusion weighted for cerebral ischemia |
| 3 mHz spike-and-wave on EEG | Absence (petit-mal) seizures |
| Atheroembolic stroke dx studies | Normal head CT. Carotid Doppler: high grade stenosis (eg, left ICA). Also do MRA, CTA, catheter angiography |
| Cardioembolic stroke imaging results: | Carotid US normal (no brain large vessel problem) |
| Cardioembolic stroke: dx studies | pulse; EKG; 24-48 hr EKG; TTE (microcavitation); TEE |
| Asymptomatic carotid stenosis: dx studies | Carotid bruit; Doppler US; MRA, CTA |
| best modality to distinguish ischemic from hemorrhagic stroke: | CT |
| TIA definitive study: | arteriography; MRA more common (less invasive) |
| TIA dx studies | CT or MRI to r/o cerebral hemo; cardiac w/u; cbc, esr, coags, antiphospholipids; Poss echo, ecg, carotid doppler |
| SAH dx studies | CT (90%); CSF: hi opening P & bloody fluid; cerebral angiography, EEG |
| EEG: focal rhythmic discharge at onset, poss no ictal activity seen: | simple partial seizure |
| EEG: interictal spikes assoc w/slow waves in temporal/frontotemp | complex partial seizure |
| MS: MRI findings | multiple characteristic white matter lesions or plaques: periventricular or subcortical U-fibers, corpus callosum lesions |
| MS: types of dx criteria | Schumacher; Poser: Macdonald |
| Ring enhancing lesion is usually: | abscess or tumor |
| Symptoms from plateau waves | Transitory episodes of altered consciousness & visual disturbances |
| Brain tumor: eval & dx | H&P; CT +/- MRI; EEG; LP; PET |
| Trauma/Bleeds: imaging of choice | noncontrast CT |
| epidural hematoma: appearance on CT | lenticular (biconvex) |
| subdural hematoma: appearance on CT | Cross suture lines and extends over larger area; Crescent shaped |
| SAH: appearance on CT | Linear, within cisterns and sulci; bleed follows outlines of the gyri |
| Normal vertebral disk on MRI: | low T1 signal, High T2 (nuc pulposus is mostly water); normal disks do not extend past margin of vert |
| Degenerative disk on MRI: | dehydrates: decreased T2; loses height |
| Spinal cord lesion types: | Demyelination; Cysts; Infarction; Tumor |
| Demyelination on MRI | patchy T2 signal; may be d/t: MS; Post infectious Myelitis; Compressive Myelopathy; Post Radiation |
| Spinal cord infarction on MRI | Gray Matter Affected Preferentially: H-pattern high T2 signal |
| Edema on MRI | T1: dark; T2: bright |
| Purpose of CT in CVA | Not dx; only to r/o other conditions that would CI some tx (tumor, bleed) |
| Brain neoplasm: imaging of choice | MRI |
| Brain neoplasm: imaging | Gray-white matter junction; marked edema; can be multiple, bilateral |
| AIDS-related CNS infxn: imaging of choice | MRI; 2/3 develop CNS infxn |
| MS imaging | MR sensitive, but not diagnostic; Periventricular T2 bright signal: inflammation |
| NPH on CT | Ventriculomegaly out of proportion to sulcal prominence |
| Imaging findings assoc w/ 4 stages of brain abscess evolution | early cerebritis (swollen/edema; high T2); late cerebritis (inc central necrosis; vasogenic edema at edges); early capsule; late capsule (well define ring) |
| Meningioma: imaging | Often along brain surface; hyperdense, homogeneous enhancement |
| Ulnar neuropathy: Dx | Hx; EMG/NCS can help find site of lesion |
| Sciatic n. palsy: Dx tests | EMG/NCS (distinguish from peroneal neuropathy); xray |
| Charcot-Marie-Tooth Dx: | H&P; DNA testing; Nerve/mx bx (confirmatory); EMG/NCS |
| Charcot-Marie-Tooth: EMG/NCS | CMT I: segmental demyelination; reduced motor & sensory conduction velocity; CMT II: axonal loss; normal/sl dec motor conduction, dec SNAPs; chronic partial denervation in affected mx |
| Dejerine-Sottas Dz: Dx | high CSF pro; EMG/NCS: dec motor velocity, sensory conduction |
| Refsum dz: Dx findings | CSF protein normal; nerve bx; EMG/NCS: dec motor velocity, sensory conduction |
| Guillain-Barre dx studies | NCS: slow S/M nerve conduction velocities; poss denervation/axonal loss; CSF high pro |
| MG dx studies | NCS: decrementing mx response; CXR to r/o thymoma; serum acetylcholine Ab |
| Huntington dz on CT | atrophy of cerebrum & caudate nucleus |
| Huntington dz on MRI/PET | decreased glucose metab |
| Neuroimaging not needed when: | No focal neuro findings; Pt has stable pattern of recurrent HA; No h/o seizures |
| HA: Consider neuroimaging when: | Neuro exam abnormal; progressively worsening HA; new persistent HA; new, rapid onset HA (thunderclap headache); HA does not respond to standard tx |
| lemon sign on US | Myelomeningocele: 2 frontal bones appear convex inward |
| banana sign on US | Myelomeningocele: elongated and curved posterior fossa 2/2 Chiari malformation |
| 5 steps to dx & tx pt w/suspected brain tumor | MRI is TOC to confirm; Pan CT of chest/abd/pelvis to detect other tumors; Bx of distant tumor or Br tumor resection to confirm patho; xrt/CTx for malig; F/U MRI, PET |
| Fisher grade is used to: | classify appearance of SAH on scan |
| Hunt Hess scale is used to: | classify severity of symptoms in SAH |
| Alzheimer dx | dx of exclusion (neuropsych eval); MRI/CT: hippocampal atrophy; amyloid on PET (Pittsburgh B); LP: inc tau, dec amyloid-beta 42 |
| NCS | uses electrodes; record response to shock (amp & timing) |
| EMG | uses needle; electrical activity observed during rest & activitation |
| NCS / EMG utility: | suspicion of peripheral nerve or mx injury; detect CTS; investigate polyneuropathy /poss etiology or radiculopathy |
| Evoked potential studies | to study conduction of CNS pathways; electrodes on scalp; brain potentials recorded in response to stim |
| Evoked potential studies: 3 kinds: | Visual; Brainstem (auditory); Somatosensory |
| Evoked potential studies: useful to dx: | MS (VEP, SSEP), spinal cord diseases |
| Visual evoked potential: optic neuritis: | After optic neuritis, the VEP will often remain abnormal indefinitely even after recovery of vision |
| SSEP | record potentials from stimulus at wrist or ankle |
| Acoustic neuroma (vestibular schwannoma): dx with: | CT or MRI; surgical tx |
| Causes of ring-enhancing lesion (mnemonic) | MAGIC DR: metastases, abscess, glioblastoma, infection (HIV/toxo, parasite) / infarct, contusion, demyelinating dz, radiation necrosis / resolving hematoma |
| Subependymal nodules (just superficial to the ependyma of lateral ventricles), calcium-containing lesions easily seen on CT scan, can be a sign of: | tuberous sclerosis complex |
Created by:
Abarnard
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