The SPECT Scanner
A Neuroimaging tool
The Single Photon Emission Computed Tomography scanner (SPECT) is a nuclear imaging test that diagrams blood flow through organs. In the brain it can give a two or three dimensional representation of activity in the brain, where blood flows to most, and where blood does not flow at all. A radioactive drug that emits gamma rays shown on the scanner is injected beforehand, and the scanner creates a series of two-dimensional pictures. A computer later grafts these into a single image, where healthy and unhealthy brain activity can be seen in three dimensions. A SPECT scan is not only for the brain, it can be used in any part of the body, and especially in the location of tumors. The difference between a SPECT scan and a PET scan is that the radioactive tracer is limited to the blood stream, whereas a PET scan absorbs the tracer into the tissue, producing a higher quality picture. This being said, SPECT scans are cheaper and more accessible than PET scans, and so they are still in common practice.
In a psychological research study, a SPECT scan could be used to measure inactivity levels in the brain, due to trauma or mental illness. It could also measure overactivity levels in the brain for similar reasons. The benefit of imaging these things is that the issue can be physically observed, which is the closest thing to concrete evidence as psychology gets.