What type of procedures are performed to assess the metabolic activity of tissues in nuclear medicine?

Scintigraphy is the correct choice for assessing the metabolic activity of tissues in nuclear medicine because it involves the administration of radiopharmaceuticals that are taken up by tissues based on their functional or metabolic activity. The radiopharmaceuticals emit gamma rays, which are detected by a gamma camera to create images that reflect the physiological function of the tissues. This allows for the visualization and quantification of metabolic processes, which is particularly useful in diagnosing conditions like cancers, cardiac diseases, and other metabolic disorders.

In contrast, X-rays and CT scans primarily focus on anatomical details rather than metabolic activity. They provide valuable structural imaging but do not offer insights into how tissues are functioning on a metabolic level. MRI scans also emphasize structural images and soft tissue differentiation but lack the ability to specifically measure metabolic processes, as they do not utilize radioactive materials that indicate tissue function.