**Core Concept**
Indium labelled WBC scan is a type of nuclear medicine imaging test that utilizes Indium-111 labelled white blood cells (WBCs) to visualize areas of inflammation or infection in the body. This technique is based on the principle of leukocyte scintigraphy, where the labelled WBCs accumulate in areas of increased inflammation, allowing for the detection of abscesses, infections, or other inflammatory processes.

**Why the Correct Answer is Right**
The Indium labelled WBC scan is used to locate areas of infection or inflammation by exploiting the phenomenon of leukocyte margination. When WBCs are labelled with Indium-111, they are injected intravenously and then accumulate in areas of inflammation, where they are phagocytosed by macrophages. The Indium-111 label is then visualized using a gamma camera, providing a clear image of the affected area. This technique is particularly useful for diagnosing and localizing infections in the abdomen, chest, or pelvis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the core concept of Indium labelled WBC scans.
**Option B:** This option is incorrect as it does not specifically relate to the use of Indium labelled WBCs for imaging.
**Option C:** This option is also incorrect as it refers to a different imaging modality altogether.

**Clinical Pearl / High-Yield Fact**
It is essential to note that Indium labelled WBC scans are more sensitive than blood cultures for detecting infections, particularly in patients with suspected abdominal or pelvic infections. This is because labelled WBCs can accumulate in areas of inflammation, providing a more accurate image of the affected area.

**Correct Answer:** D.