Question

Assertion (A): 99mTc-HIDA/PIPDA (iminodiacetic acid) scan is a non-invasive tool for biliary scintigraphy. Reason (R): It shows excretion by hepatocytes and displays biliary anatomy.

• A. Both A and R are individually true and R is the correct explanation of A
• B. Both A and R are individually true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Think about how the tracer travels from the bloodstream into the liver cells and then into the bile ducts.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question tests whether the HIDA/PIPDA scan is really a non-invasive biliary imaging test, and whether hepatocyte uptake and excretion is the correct reason it can display biliary anatomy.

Step 2: Key Concept or Approach:
Technetium-99m labelled iminodiacetic acid derivatives, such as HIDA and PIPDA, are injected intravenously and are taken up selectively by functioning hepatocytes in the same way as bilirubin, then actively excreted into the bile canaliculi and the biliary tree. A gamma camera tracks this uptake and excretion over time from outside the body, without any incision or duct puncture.

Step 3: Working Through the Options:
A is true, this scan genuinely is a non-invasive nuclear medicine test used for biliary scintigraphy. R is also true, and it correctly explains A, because it is precisely this hepatocyte uptake and biliary excretion mechanism that allows the scan to outline the biliary anatomy and confirm bile flow, which is why it is used to diagnose acute cholecystitis by non-filling of the gallbladder, biliary atresia, and postoperative bile leaks.

Step 4: Conclusion:
Both statements are true and R correctly explains A, matching the option stating both are true with R as the correct explanation.