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

In which scenario do hemangiomas exhibit peripheral enhancement?

1. Hypoattenuating

2. Isoattenuating

3. Hyperattenuating

4. Non-enhancing

The correct answer is: Hypoattenuating

Hemangiomas are vascular tumors that often present with characteristic imaging appearances. In particular, peripheral enhancement is a hallmark feature, which is most commonly observed in lesions that are hypoattenuating. When hemangiomas are evaluated using imaging techniques like CT scans or MRI, they typically show lower attenuation compared to surrounding tissue due to their high vascularity and slower blood flow within the lesion. This hypoattenuating characteristic is key because, upon contrast administration, the vascularity allows for the periphery of the hemangioma to enhance as the contrast fills the vascular spaces. The surrounding normal tissues, which generally have a higher attenuation, can lead to a significant contrast difference that highlights the peripheral enhancement of the hemangioma. This contrast effect helps in differentiating hemangiomas from solid masses or lesions that may not exhibit this peripheral enhancement pattern. In contrast, isoattenuating lesions would not demonstrate the same contrast effect due to similar attenuation with surrounding normal tissue, and hyperattenuating or non-enhancing lesions would not typically allow for the visualization of peripheral enhancement due to either increased density or absence of blood flow. Understanding these imaging characteristics is crucial for accurate diagnosis and management of hemangiomas.