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35 Cards in this Set
- Front
- Back
What is Tc-99m-IDA and name one of its derivatives? |
iminodiacetic acid (IDA) Mebrofenin |
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List several indication of its use (IDA). |
1. hepatobiliary scintigraphy 2. trans-splenic PSS 3. solid-phase gastric emptying |
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The liver receives ____% of its blood supply from the portal venous system and ____% from the hepatic arteries. |
70% from portal 30% from hepatic arteries |
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Hepatobiliary agents are analogues of what? |
Lidocaine |
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What is the percentage of first pass extraction of lidocaine by the liver? |
> 90% |
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IDA is loosely bound to albumin which accomplishes what? |
increased hepatic uptake and decreases renal excretion |
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What is IDA's mechanism of location? |
active transport on the hepatocyte membrane via a bilirubin anion receptor |
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List 5 specific indications for hepatobiliary scintigraphy. |
1. function 2. morphology 3. patency 4. diff. btwn. intra vs. extrahepatic obstruction 5. biliary disease |
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What acquisition and positioning are advised for hepatobiliary scintig.? |
Frame mode - dynamic right lateral |
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When should IDA be given and at what point can hepatic morphology be evaluated (time of peak uptake)? |
give simultaneously with injection morphology seen best at 6-8 minutes |
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In a normal patient, what percentage of IDA goes to the hepatocytes (normal extraction), and what percentage remains in the vascular space, ultimately reaching the heart? |
95% to liver 5% to heart |
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In a normal patient, after what time period should one be unable to see activity outside of the liver? |
> 5 minutes |
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What is the normal half-life for hepatic excretion? |
19 minutes |
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List 4 causes of a prolonged hepatic excretion half-life. |
1. cholestasis 2. cholangiohepatitis 3. chronic extrahepatic obstruction 4. hepatic parenchymal disease (hepatocellular) |
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In an abnormal dog, what percentage of IDA enters the hepatocytes, what percentage remains in the vascular space (and goes to the heart), and how is liver activity affected on the curve? |
a. 50% to liver b. 50% to heart c. sharp decline in activity (then slow decline) |
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When should GB and small intestinal activity be seen in the normal patient? |
< 1 hour |
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What drug can be administered in order to evaluate GB ejection fraction and emptying rate? |
CCK |
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a. What is the normal GB ejection fraction? b. What is the normal GB emptying rate? |
a. 40 - 80% b. 10% per minute |
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In the case of a biliary obstruction, what subsequently elevated substance competes with IDA uptake, resulting in reduced IDA uptake and HEF? |
bilirubin |
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What effect to opioids have upon IDA transit to the intestine? |
prolonged transit (constriction of sphincter of Oddi) |
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What effect will acute cholecystitis (without obstruction) have upon HEF, liver excretion, and biliary clearance respectively? |
none, none, and none |
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What effect will chronic cholecystitis have upon HEF and liver excretion, respectively? |
reduced HEF and prolonged liver excretion |
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What effect will chronic cholecystitis have upon GB clearance? |
prolonged (GB unseen at < 1 hour, but seen by 4 hours) |
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What effect will extrahepatic cholestasis have upon HEF and hepatic excretion respectively? |
normal HEF prolonged hepatic excretion |
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With what hepatobiliary disease process do the GB and SI appear as a virtually permanent void/photopenic region? |
extrahepatic cholestasis |
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What are the two most important criteria for diagnosing a partial obstruction of the biliary tract? |
1. Very delayed identification of intestinal activity (~18 hours). 2. Decreased volume of intestinal activity. |
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What is a common appearance of the gallbladder in case of partial and complete obstructions? |
a large and photopenic void |
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In cases where there is complete non-visualization of the small intestine, what disease process would be expected? |
chronic extrahepatic obstruction |
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With regard to trans-splenic portal scintigraphy, what is one reason one might select Mebrofenin over pertechnetate. |
Mebrofenin has a higher first-pass extraction by the liver.
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What radionuclide is commonly used for solid-phase gastric emptying studies? |
Tc-99m - Mebrofenin (it has a > 90% solid-phase retention and stability - just add to wet or dry food) |
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How long should patients be fasted for a solid-phase study? |
12 - 18 hours |
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What acquisition mode and positioning are advised for solid-phase studies? |
Frame mode - static right and left lateral abdomen |
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Define titurition. |
mixing without emptying |
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Gastric emptying of the solid-phase is dependent on what 3 factors? |
1. The amount fed (Kcal/Kg body weight) 2. The amount of water concurrently consumed 3. The diet form (canned vs. kibble) |
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List the 3 phases of normal, solid-phase, gastric emptying. |
1. Initial Lag Phase (titurition/mixing) 2. Linear Phase (initial emptying) 3. Delayed Phase (fiber gastric emptying) |