SPECT helps illuminate the variance of illnesses.
Psychiatry remains the only medical specialty that rarely looks at the organ it treats.
If we agree that mental disorders and aberrant behaviors are related to functional brain problems, and that single photon emission computed tomography (SPECT) imaging is a reliable measure of regional cerebral blood flow and thus activity patterns, how can we not take advantage of this valuable tool when faced with complex and unresponsive patients? How can we evaluate brain function unless we look? Otherwise, we are left to deduce or guess what may be going on in our patients' brains.
In experienced hands, SPECT scans can be helpful in numerous problems that commonly present to psychiatrists. A scan can show brain areas implicated with specific clinical problems, such as the prefrontal cortex with impulsivity and the hippocampus with memory issues. SPECT frequently uncovers unexpected findings that may be contributing to presenting problems, such as toxicity or brain trauma. SPECT can help types of obsessive-compulsive disorder, or stabilize erratically firing temporal lobes often seen in aggression. Before and after SPECT can also show the effects of prescribed medication to give guidance on how to adjust treatment.
If the above is true, why don't more psychiatrists use imaging in clinical practice? First, clinical imaging is not part of psychiatric training. Most psychiatrists do not know when to order scans or how to use the information. Another reason is the mistaken concern that imaging may replace the physician. Imaging should never be used alone to make a diagnosis or direct a treatment decision. It is only part of the puzzle.
Another misconception is that SPECT advocates want to perform imaging tests on every psychiatric patient. I think of SPECT like radar. On a clear day, radar isn't necessary to land a plane. So, too, in psychiatry, a careful clinical evaluation can accurately diagnose most problems. However, radar is needed when there is trouble seeing the airport. SPECT's best use is in complex or treatment-resistant cases. Withholding imaging in unclear cases does an injustice to our patients and may even harm them. Ineffectively treated psychiatric disorders are expensive and dangerous.
Some critics argue that brain imaging isn't ready for clinical use because research has yet to find any abnormality that is specific to a single psychiatric disorder. These critics miss the point. Of course, studies that use DSM-IV criteria as a standard for patient selection will not yield a single pattern of abnormalities. That's why we have a range of treatments for a single diagnosis; not every patient responds to every treatment, and many standard treatments directed at phenotypic subsets make patients worse. There is significant heterogeneity within DSM-IV diagnoses. SPECT helps us understand the variance of illnesses, such as depression and ADHD, rather than diagnosing these disorders.
Another argument against imaging is that the notion that studies to interpret findings are insufficient studies. Clearly, more research is needed, but to say that not enough peer-reviewed research exists is entirely false. Thousands of peer-reviewed imaging articles provide a sound clinical basis for interpreting findings.
One of the most powerful implications of imaging is that it immediately decreases the stigma associated with mental illness. It shows patients and their families that they are dealing with real medical problems, and increases compliance. We have nothing else in psychiatry that results in such an immediate and strong intervention.