American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What is the typical imaging appearance of hepatocellular carcinoma (HCC) on a contrast study?

1. Iso/hypointense

2. Isoattenuating

3. Hyperattenuating

4. Hypoattenuating

The correct answer is: Iso/hypointense

Hepatocellular carcinoma (HCC) typically presents as iso or hypointense relative to the surrounding liver parenchyma on contrast-enhanced imaging. This is particularly evident during the arterial phase of imaging, where HCC lesions often show less enhancement compared to the surrounding liver tissue. The typical enhancement pattern includes being isoattenuating or hypocellular during the equilibrium or portal venous phases, which further supports the characterization of the tumor. Elevated levels of vascularity in HCC can sometimes cause it to appear hyperattenuating during the arterial phase, yet this is not the common appearance overall when evaluated across multiple phases. The diagnosis of HCC is heavily reliant on the imaging characteristics observed during these contrast studies, making recognition of the iso/hypointense nature of HCC essential in clinical practice. Understanding that the imaging findings demonstrate this iso/hypointense appearance is critical for distinguishing HCC from other hepatic lesions that exhibit different patterns on imaging, thus aiding in accurate diagnosis and subsequent management.