On dynamic contrast-enhanced MRI of the liver, a lesion shows arterial phase enhancement with rapid washout in the portal venous and delayed phases, resulting in a 'capsule appearance' in the delayed phase. This pattern is diagnostic of:
- A Hemangioma
- B Hepatocellular carcinoma ✓
- C Focal nodular hyperplasia
- D Cholangiocarcinoma
Correct answer: B. Hepatocellular carcinoma
Explanation
The LI-RADS/AASLD major imaging criteria for HCC in a cirrhotic liver include arterial phase hyperenhancement (APHE) + washout in portal venous or delayed phases + enhancing capsule in delayed phase. This 'arterial enhancing then washing out' pattern reflects the dual blood supply shift in HCC (predominantly arterial) vs. surrounding liver parenchyma (portal dominant). Hemangiomas show centripetal fill-in ('flash fill' in small ones). FNH shows a central scar enhancing in delayed phase. Cholangiocarcinoma shows progressive delayed enhancement (central fibrosis).
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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