Thanks to a new diagnostic imaging technique, physicians now have an objective test to evaluate patients for parkinsonian syndromes, such as Parkinson’s disease. DaTscan™ (ioflupane idodine-123 injection) is a contrast agent that used with a SPECT scanner to detect dopamine transporters (DaT) in suspected parkinsonian syndromes.
What is DaTscan™?
This noninvasive test, DaTscan™, is an imaging technology that uses small amounts of a drug to help determine how much dopamine is available in a person’s brain. A single photon emission computed tomography (SPECT) scanner, then measures the amount and location of the drug in the brain and helps to evaluate whether you have a Parkinsonian syndrome.
How does it work?
The patient receives an injection of the imaging agent. After injection, the compound can be visualized by a special detector called a gamma camera. This so-called scan measures something called the dopamine transporter (DaT), and it can help a doctor determine if patients are suffering from essential tremor, vs. Parkinson’s disease or another parkinsonism (i.e., other problems affecting dopamine systems that have symptoms of Parkinson’s disease).
PET scans and DaT/SPECT scans examine the "function" of the brain rather than its anatomy. This is an important point because unlike in strokes and tumors, the brain anatomy of a Parkinson’s disease patient is largely normal. These scans can show changes in brain chemistry, such as a decrease in dopamine, which identify Parkinson’s disease and other kinds of parkinsonism. There are several compounds available for use in both PET and SPECT scanning; however PET scans typically focus on glucose (sugar) metabolism, and DaT/SPECT scans focus on the activity of the dopamine transporter.
DaTscans™ use a substance that "tags" a part of a neuron in the brain where dopamine attaches to it, showing the density of healthy dopamine neurons. Thus, the more of the picture that "lights up", the more surviving brain cells. If the parts of the brain where dopamine cells should be remain dark in the scan, an expert reader may diagnose early brain degeneration. This could mean either Parkinson’s disease or parkinsonism.
Are there side effects to DaTscan™?
The side effects are minimal (e.g. headache, dizziness, increased appetite and creepy crawly feeling under the skin).
Can DaTscan™ diagnose Parkinson’s?
DaTscan™ cannot diagnose Parkinson’s disease. These scans are used to help your physician confirm a diagnosis. The results of a DaTscan™ can be used to help rule out other diseases that may have similar symptoms, like essential tremor, especially for individuals early in the course of their disease. However, there are several other diseases, multiple system atrophy (MSA) or progressive supranuclear palsy (PSP), which can also produce a loss of dopamine in the brain. A DaTscan™ cannot differentiate between those diseases and Parkinson’s.