To diagnose someone with PD today, your Neurologist will use a compilation of clinical signs and symptoms. In other words, there is not currently a specific medical test to make the diagnosis. Sometimes, your provider might recommend a DaTscan to help them determine a diagnosis. Let's learn more about DaTscan.
What is a DaTscan?
A DaTscan is a type of image that involves nuclear medicine. A DaTscan uses an injectable drug called Ioflupane I 123. A DaTscan uses SPECT (Single Photon Emission Computed Tomography) imaging to produce an image of your brain. The injectable drug attaches to Dopamine Transporter (DAT) in the brain, which helps show to how much dopamine is in your brain. If the scan shows diminished activity, this suggests that there is a diminished level of dopamine.This information along with your clinical signs and symptoms will help lead to a diagnosis.
How accurate is a DaTscan?
It is important to highlight that a DaTscan is not a "Parkinson's test" therefore it is only as accurate as your other PD symptoms. When looking at the complete picture of a person searching for a diagnosis, the clinical symptoms like sleep changes, tremor, stiffness, slowness, and mood changes are the most important pieces of the puzzle. However, there is one study that showed that the diagnostic accuracy of diagnosing early PD was equal between just a clinical exam or just a DaTscan.
A DaTscan will appear abnormal with any disease that impacts dopamine, like Parkinsonisms, Progressive Supranuclear Palsy, Corticobasal Ganglionic Degeneration, and Multiple System Atrophy. Therefore, a DaTscan should not be used in isolation.
DaTscans are not able to determine how much of the dopamine system is impaired, so you cannot use this test to assess for stage of PD and you cannot use this to screen for the disease before any motor symptoms become present.
What to expect?
First, iodine via a liquid or pill form will be used to help protect your thyroid from absorbing radiation from the DaTscan medication. You then wait 30-60 minutes to receive the injection of the medication. Then, you must wait for 3-6 hours for the medication to get to the brain. Your provider will be able to help you determine a shorter and more accurate time frame.
The scan will take around 40 minutes to complete. You will be positioned on your back with your head resting in a small cradle. You will have to stay still during the scan. If you have tremors or dyskinesia, a flexible restraint may be used to keep your head still. The machine will slowly rotate around your head during the scan.
After the scan you may feel some soreness at the injection site, a headache, or dry mouth. Most people report only mild symptoms. It is recommended to drink a lot of water to help your body process the medication.
Why didn't my doctor order a DaTscan?
At risk of sounding like a broken record, a DaTscan does not definitively rule in or rule out PD. Your clinical symptoms are still the most important aspect of your diagnosis. If you have obvious symptoms, your doctor may not think it is necessary to expose you to the radiation. There is always a risk when we expose our body to radiation, and limiting this exposure as much as possible is something that the medical community strives to do. Not receiving the exam does not mean that your provider is not making an accurate diagnosis.
Summary
DaTscan is a test that can help with the diagnosis of PD, but clinical symptoms are still the primary way to diagnose PD.
DaTscan cannot tell you the stage or progression of your Parkinson's.
DeTscan cannot differentially diagnose between PD and other dopamine impacted neurological conditions.
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