Liver Disease and Tumors for Medical Students Practice Test

In imaging, washout for HCC means the lesion, which often shows strong arterial enhancement, becomes less enhanced than the surrounding liver in the portal venous or delayed phases. This happens because HCC tends to have a robust arterial blood supply but lacks normal portal venous inflow and clears contrast faster than the liver tissue, so it looks relatively hypoenhanced later on. Thus, the best description is that the lesion appears hypoenhanced relative to the liver in the portal venous or delayed phase.

The idea that enhancement would increase only in the arterial phase doesn’t capture the washout effect seen later, and no-change across phases or enhancement limited to bile ducts wouldn’t describe a typical HCC washout pattern.