Metabolic activity in different areas of the brain can best be visualized by means of

The answer to this question would be: P ositron Emission Tomography (PET) scan

Positron emission tomography is a modality that can be used to examine the blood flow, oxygen use, and glucose metabolism. Using this, you can visualize the brain activity. The area with the disease will have decreased activity when the cell died or increased activity like cancer.