Dopamine Transporter Imaging may allow for earlier and more accurate diagnosis of patients with Parkinsonian syndromes. These include Parkinson Disease, Lewy Body Dementia, Multiple System Atrophy, and Progressive Supranuclear Palsy. Here’s how it works:
Radiotracer Injection: The process begins with the injection of a small amount of a radioactive tracer, typically Ioflupane I-123, into the bloodstream. This tracer is designed to bind specifically to dopamine transporters in the brain.
Absorption and Binding: Once injected, the tracer travels through the bloodstream and is absorbed by the brain, where it binds to the dopamine transporters located in the striatum, a region of the brain that controls movement.
SPECT Imaging: After allowing time for the tracer to bind to the dopamine transporters (usually a few hours), the patient undergoes a Single Photon Emission Computed Tomography (SPECT) scan. The SPECT camera rotates around the head, capturing detailed images of the brain.
Image Analysis: The resulting images show the distribution of dopamine transporters in the brain. In individuals with normal dopamine function, the images typically show a comma-shaped pattern of tracer uptake in the striatum. However, in conditions like Parkinson’s disease, there is reduced dopamine transporter activity, leading to an abnormal, reduced uptake pattern, often appearing as a period shape rather than a comma.
Diagnosis Support: The DaTscan images are then analyzed by a radiologist or neurologist to assess the level of dopamine transporter activity. Reduced activity suggests a loss of dopamine-producing neurons, which is characteristic of Parkinson’s disease and some other movement disorders. This information, combined with clinical evaluation, helps doctors make a more accurate diagnosis.