**Core Concept**
Adrenal adenomas are typically characterized by specific imaging features on computed tomography (CT) scans, which help differentiate them from other adrenal lesions. These features include low attenuation, homogenous density, well-defined borders, and the absence of calcification.

**Why the Correct Answer is Right**
Adrenal adenomas typically exhibit a slow washout of contrast material on CT scans, which is due to the presence of lipid-laden cells within the tumor. This slow washout is a key feature that distinguishes adenomas from non-adenomas, such as metastases or pheochromocytomas. Rapid enhancement and early washout of contrast material are more characteristic of malignant lesions. In contrast, adenomas typically show a gradual increase in attenuation after contrast administration and a prolonged retention of contrast material.

**Why Each Wrong Option is Incorrect**
**Option A:** Low attenuation is a characteristic feature of adrenal adenomas, which are often composed of lipid-rich cells. This feature is commonly observed on non-contrast CT scans.
**Option B:** Homogenous density and well-defined borders are also typical features of adrenal adenomas, which usually appear as well-circumscribed masses on CT scans.
**Option D:** Calcification is indeed rare in adrenal adenomas, and when present, it is often small and peripheral.

**Clinical Pearl / High-Yield Fact**
When interpreting adrenal lesions on CT scans, remember that the presence of calcification, particularly in the form of a central, thin calcification, is more suggestive of an adrenal adenoma. Conversely, the absence of calcification and the presence of irregular margins or heterogeneous enhancement should raise suspicion for a malignant lesion.

**✓ Correct Answer: C. Enhances rapidly, contrast stays in it for a relatively longer time and washes out late**