What method of localization does Tc exametazime (HMPAO) primarily use?

• A. Passive diffusion
• B. Active transport
• C. Protein binding
• D. Perfusion

Answer: (D)

Tc exametazime, also known as biologically active HMPAO (hexamethylpropyleneamine oxime), primarily utilizes perfusion as its method of localization. In imaging studies, this radiopharmaceutical is often used for assessing regional cerebral blood flow and detecting areas of ischemia or infarction in the brain.

Perfusion refers to the process by which blood is delivered to tissues, and it is crucial for the localization of Tc exametazime. After intravenous administration, the compound crosses the blood-brain barrier in areas where blood flow is adequate, allowing for the imaging of brain activity based on perfusion patterns. In regions of the brain with reduced blood flow, the uptake of HMPAO decreases, which can highlight areas of concern.

By using this method of blood flow dynamics, Tc exametazime enables effective visualization of brain function and perfusion, making it a valuable tool in nuclear medicine, particularly in neurological studies.