Once a sample of Technetium has been injected into the body, it can collect in certain areas of the body, depending on its exact make-up. If technetium-labeled diethylenetriamine (DTPA) is used, the substance collects in the brain, and so is used for brain imaging.
The mostly widely used type of technetium based diagnostic imaging is bone imaging. Technetium labeled phosphate compounds such as pyrophosphate are used. These compounds are adsorbed into the bone structure, and their distribution is directly proportional to the bones metabolic activity. Since most bone disorders result in increased blood flow and metabolic activity, they show up well compared to healthy bone.
It can be seen from the above scan that the patient is suffering from a bone disorder in their right leg. In this case it has been caused by Paget's disorder, a rare bone disease.
Many other organs can be imaged in a similar fashion, for example the heart, liver or even veins and arteries.