**Core Concept**
Localization of insulinoma, a rare type of pancreatic neuroendocrine tumor, requires precise imaging techniques due to its small size and potential for malignant behavior. Accurate localization is crucial for surgical planning and management.

**Why the Correct Answer is Right**
Selective angiography, also known as arteriography, is a highly effective imaging modality for localizing insulinomas. This technique involves injecting a contrast agent into the arterial supply of the pancreas, allowing for detailed visualization of the tumor's blood vessels. The characteristic hypervascular pattern of insulinomas, including early venous drainage and a "nidal" or "capillary" blush, can be identified on selective angiography. This information is essential for guiding surgical resection and minimizing the risk of tumor recurrence.

**Why Each Wrong Option is Incorrect**
**Option A:** Contrast computerized tomography (CT) may show the presence of an insulinoma but lacks the sensitivity and specificity of selective angiography for precise localization.
**Option B:** Magnetic resonance imaging (MRI) can also demonstrate the presence of an insulinoma but is less sensitive than selective angiography for small tumors and may not provide the same level of detail regarding tumor vascularity.
**Option C:** Somatostatin receptor scintigraphy (SRS) may be useful for localizing neuroendocrine tumors that express somatostatin receptors but is not the preferred method for insulinoma localization due to its lower sensitivity and specificity.

**Clinical Pearl / High-Yield Fact**
Insulinomas are typically hypervascular and may show early venous drainage on selective angiography, which can be a key diagnostic feature for distinguishing them from other pancreatic lesions.

**Correct Answer:**
✓ Correct Answer: D. Selective angiography