On a brain image performed with Exametazime, which area is visualized as a high concentration?

In nuclear medicine imaging, particularly when using Exametazime (also known as HMPAO), the agent is particularly sensitive to the perfusion of cerebral tissue, with a strong affinity for gray matter. Exametazime is a radiopharmaceutical that localizes in areas of the brain with higher metabolic and perfusion activity, which predominantly occurs in the gray matter.

Gray matter is where synapses and neuronal cell bodies are densely packed, leading to higher rates of metabolism and blood flow compared to white matter, which primarily consists of myelinated axon fibers and has a lower metabolic rate. Thus, in a brain image using Exametazime, it is the gray matter that will show up with a high concentration of the radiotracer, clearly indicating areas of increased cerebral activity. This contrasts with other brain regions such as the white matter, where concentration will be notably lower, reflecting its different functional and structural characteristics.

The frontal and temporal lobes, while they do contain gray matter and may show uptake depending on activity, are not the regions primarily referred to in the context of overall gray matter visualization. Therefore, while they may be highlighted in specific functional tasks, they do not represent the overall high concentration that Exametazime typically visualizes