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

What imaging characteristic do liver metastases generally exhibit?

1. Hypoattenuating

2. Hyperattenuating

3. Isoattentuating

4. Mixed density

The correct answer is: Hypoattenuating

Liver metastases typically exhibit a hypoattenuating characteristic on imaging studies, such as CT scans. This means that these lesions appear darker compared to the surrounding liver tissue. The reason for this hypoattenuating appearance is generally due to the higher water content within the metastatic lesions, which is often associated with necrosis or high cellularity in malignant tumors. In contrast, hyperattenuating lesions would appear brighter and are more commonly associated with conditions such as hemangiomas or focal nodular hyperplasia instead of metastases. Isoattenuating lesions would not show a significant difference in density compared to the surrounding liver tissue, which is also less typical for metastases, as these lesions often create a contrast. Mixed density refers to lesions that contain both hypoattenuating and hyperattenuating areas, which is not characteristic of the majority of liver metastases. Thus, the commonly observed hypoattenuating characteristic provides a useful imaging clue when evaluating potential liver metastases, aiding in diagnostic processes.