**Question:** Radiological feature of ischemic colitis is –

A. Mottled enhancement on CT scan
B. Enhancement in left-sided colitis
C. Homogeneous enhancement on CT scan
D. Absence of enhancement on CT scan

**Core Concept:**
Ischemic colitis is a condition characterized by reduced blood flow to the colon, leading to tissue hypoxia and damage. This can result from various causes, such as thromboembolism, vasospasm, or mesenteric ischemia. The radiological features are essential for diagnosis and differentiation from other causes of colitis.

**Why the Correct Answer is Right:**
Correct Answer: D. Absence of enhancement on CT scan

Ischemic colitis is characterized by reduced blood flow and delayed perfusion, leading to decreased arterial and venous enhancement. In a CT scan, this results in a lack of enhancement in the affected colon compared to the surrounding normal colon. This is a crucial feature as it helps differentiate ischemic colitis from infectious colitis, where enhancement is typically seen due to inflammation and increased blood flow.

**Why Each Wrong Option is Incorrect:**
A. Mottled enhancement on CT scan - This is incorrect because the mottled enhancement could represent other inflammatory or neoplastic conditions, not specifically ischemic colitis.
B. Enhancement in left-sided colitis - This is incorrect as ischemic colitis can affect the entire colon, not just the left-sided colon.
C. Homogeneous enhancement on CT scan - This is incorrect because homogeneous enhancement is more related to inflammatory or neoplastic conditions, not ischemic colitis.

**Clinical Pearl:**
Understanding the radiological features of ischemic colitis is essential for accurate diagnosis and timely management. In suspected cases, a CT scan with contrast can help identify the characteristic absence of enhancement in the affected colon.