Last February I underwent a SPECT scan as part of a Parkinson's disease research program, the object of which is to determine if it is possible to diagnose PD before its overt symptoms appear. There seems to be a familial form of PD in my family, since my mother and older brother had it, and I was diagnosed with it 5 years ago. My unaffected sister and two unaffected nieces, daughters of my late affected brother, were also scanned.

Before we went to have the scans done, I read up on the SPECT procedure and instrumentation as it is used in imaging brain structures of particular interest for this particular program. In our case, the target was the dopamine transporter function in the putamen of the basal ganglia, and the tracer that was used was an Iodine 125-labeled compound taken up specifically by certain cells in that organ. The amount of the label taken up 61-18 hours after IV injection is measured as a surrogate marker for dopamine re-uptake by dopaminergic neurons in the putamen. As PD progresses, this function decreases, and is 70-80% gone before clinical symptoms appear. The researchers doing the study have apparently identified the gene mutation in our family related to PD, and they are looking for changes in dopamine transproter function in the yet unaffected family members that might indicate early stages of PD.

My point in posting this is simply to share with you what I know about SPECT; that the technique may be used to image different functional areas in the brain, depending on the chemical nature of the tracer substances that are utilized.

Robert