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IV Procedures & CM
Study Questions
| Question | Answer |
|---|---|
| The iodine in the CM increases the _____ of the xray photons. | attenuation |
| The increase in brightness on CT image associated with tissues perfused by IV contrast agents is: | enhancement |
| _____ IV CM divide into charged particles (ions) when in a solution, like the patient's blood stream. | Ionic |
| _____ IV CM do not divide into charged particles when in solution. | Non-ionic |
| When a ____ CM is injected, the entire molecule remains intact as it passes through the body and is excreted in the same form by kidneys. | non-ionic |
| Non-ionic CM belongs to the _____ osmolar category of IV CM. | low |
| What is the concentration of particles in a non-ionic, low osmolar IV CM? | around 500 to 850 mOsm/kg |
| What is the concentration in an ionic, high osmolar IV CM? | around 1300 to 1600 mOsm/kg |
| IV CM are said to be ____ or ____ compared to blood plasma. | hyperosmolar or hypertonic |
| _____ solutions will cause a net movement of water from within the tissues into the vascular space. | Hypertonic |
| How can the severity of the osmotic effect, and the associated reaction, be reduced? | by administering non-ionic, low osmolar CM |
| _____ acts by constricting smooth muscle and venules, dilating arterioles, producing localized edema, accelerating heart rate, lowering BP, and increasing gastric and mucous secretions. | Histamine |
| What category of reaction mechanism can be caused by anything other than the properties of the CM, the amount injected, or the injection rate? | idiosyncratic reaction mechanism |
| What injection rate would you use for a CTA? | 4 to 5 cc/sec |
| Which vein drains the dorsal part of the hand, and runs between the pectoralis major and deltoid muscles, through clavipectoral fascia and finally joins axillary vein? | cephalic vein |
| Which vein is the vessel of choice for injecting IV CM? | basilic vein |
| What causes the basilic vein to remain more stationary than the cephalic vein when starting an IV in the cubital fossa? | There is an anastomosis between the basilic and cephalic veins at elbow which helps basilic vein to remain quite stationary within subcutaneous tissue |
| How much should the needle tip be withdrawn before advancing the catheter up the vein? | 2 to 3 mm |
| What side of the heart receives blood returning to the heart through the superior and inferior vena cava? | the right side of the heart |
| What defines the bolus phase of enhancement? | There is a significant density difference between the abdominal aorta and inferior vena cava |
| During which of the contrast enhancement are CTA images of optimal quality? | during the bolus phase of contrast enhancement |
| What characterizes the non-equilibrium phase of enhancement? | there is a 10 to 30 HU density difference between the abdominal aorta and inferior vena cava |
| During what phase of CM enhancement does the bolus start to disburse into capillaries, and then into veins? | non-equilibrium phase |
| During which phase of enhancement do we generally obtain the best differentiation of structures in soft tissues as a result of CM injection? | non-equilibrium phase |
| What characterizes the equilibrium phase of contrast enhancement? | there is a density difference of less than 10 HU between the abdominal aorta and inferior vena cava |
| During which phase of enhancement is the agent's concentration in the veins similar to the concentration of arteries? | equilibrium phase |
| The liver receives about ___% of its blood from the portal vein and about ___% from the hepatic vein. | 80%; 20% |
| When does the hepatic arterial phase of liver enhancement occur? | 20 to 40 seconds after start of injection |
| When does the portal venous phase of liver enhancement occur? | 60 to 90 seconds after start of injection |
| If scanning is performed in the liver later than portal venous phase, in equilibrium phase, many hepatic tumors become ___ with liver tissue and may not be visible on images. | isodense |
| What can be administered in order to inhibit gastric peristalsis? | glucagon |
| Barium sulfate solutions used in CT are much more dilute than those used in radiography, typically containing a ____ to ____% barium sulfate suspension. | 1% to 3% |
| What are the concentrations of iodinated oral agents? | from 6 to 9 mg of iodine per mL |
| Why are oral iodinated CM tolerated so much better than IV iodinated CM? | because oral agents use a much lower concentration of iodine |
| How much of iodinated oral contrast is absorbed by the body? | around 0.1% to 0.5% |
| What is a typical dose of IV contrast for a head scan? | 100 mL |
| About how long would you wait before scanning the head after injection of IV CM for studies involving metastatic disease, AIDS, or multiple sclerosis? | About 45 minutes |
| Why are IV CM used in studies of the neck? | for differentiation of blood vessels from lymph nodes and outline the epidural venous plexus |
| Blood vessels and vascular tumors appear ___ (more/less) dense than lymph nodes when IV CM is used. | more |
| What is the typical dosage of IV CM, rate, and delay time for studies of the neck? | 100 to 125 mL; 2 to 2.5 mL/s; 35 sec |
| When scanning the brachial plexus, it is advantageous to do what? | inject in the arm which is contralateral to side of primary interest in order to avoid streak artifacts |
| What is the typical dose of IV CM, rate, and delay time for CT chest? | 100 mL; 3 mL/sec; 20 to 25 sec |
| When scanning an abdomen, it is important to complete scanning before the organ of interest has reached the ____ phase of enhancement. | equilibrium |
| Tumors of the liver typically receive their blood supply from which vessel? | hepatic artery |
| What is the typical dose of IV CM, rate, and delay time for CT pelvis? | 100 mL; 2 to 3 mL/sec; few minutes to allow for ureter and bladder enhancement |
| What would be a typical pediatric dose of IV CM for conventional, serial scan? | 2 mL/kg of body weight |
| What would be a typical pediatric dose of IV CM for a helical scan? | 1.5 mL/kg of body weight |
| What can be increased to scan the vessel more quickly in a CTA exam? | pitch |
Created by:
sspatel
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