Tremors, slow movements, changes in speech and rigid posture are common symptoms that may lead a physician to make a diagnosis of Parkinson’s disease, the neurodegenerative disorder that affects 1.5 million Americans. But because a patient’s symptoms can start out being subtle and progress over time, a proper diagnosis can take several years. Clinical exams are also often inconclusive and can lead to a misdiagnosis of similar movement disorders such as essential tremors.
The National Parkinson Foundation estimates that 50,000 to 60,000 new cases of Parkinson’s disease are diagnosed in the United States each year, but an accurate diagnosis can take up to six years. Many mistakenly attribute the first symptoms to the normal aging process.
In January 2011, the Food and Drug Administration approved a procedure called DaTscan (Dopamine Transport Scan). DaTscan is a radiopharmaceutical used with single-photon emission computed tomography (SPECT) scanners for detecting dopamine transporters which are deficient in patients with Parkinson’s disease. The test is used to confirm or refute a suspected diagnosis of Parkinson’s disease when the patient presents inconclusive or atypical symptoms.
With DaTscan, the injected drug, Iofluplane I 123, localizes to dopamine transporter molecules in the brain and provides information about how much dopamine is available in a person’s brain. The amounts of side effects from the test are few.
The scan provides doctors with an image of the brain’s dopamine receptors lit up in blue and pink. Normal scans are characterized by two symmetric comma- or crescent-shaped focal regions of activity mirrored about the median plane. Striatal activity is distinct, relative to surrounding brain tissue.
Abnormal scans showing possible parkinsonian syndrome may have two period-like, circular shapes; a combination of one circular and one crescent shape; or only one circular or one crescent shape.
DaTscan provides important physiological information on what’s going on in the brain. Prior to this test, physician assessment was purely clinical. The information derived from the DaTscan can confirm that the patient has one of the Parkinsonism syndromes, which include Parkinson’s disease, Supra-nuclear palsy and multiple system atrophy. If the scan shows normal dopamine transporter density, that information is also useful to suggest the cause of the patient’s tremors are not due to a Parkinsonism syndrome.
When a patient is suspected of having Parkinson’s, a neurologist will typically prescribe medication to see if the patient responds, but that can often lead to a misdiagnosis or unnecessary treatment and lost time. DaTscan gives physicians the ability to provide a definitive diagnosis which is of great clinical benefit to guide appropriate disease managements. The earlier treatment begins the better chance we have in improving patients’ lives and stave off detrimental effects of the disease process.
DaTscan is a Drug Enforcement Administration Schedule II controlled substance, so hospitals and nuclear imaging centers that administer DaTscan must have infrastructure dedicated to quality control, handling and dispensing of DEA Schedule II radioactive drugs used for diagnosis and treatment. The manufacturer of the radiopharmaceutical has established a certification program to assure high quality exams are performed. Halifax Health was selected to be the first healthcare facility in East Central Florida to offer DaTscan due to its designation as a regional Center of Excellence for Volusia, Flagler and St. John’s counties and already having the highly-trained physicians, technology and infrastructure in place to begin offering the examination. This includes Halifax Health’s board certified subspecialists in Nuclear Radiology, an experienced technical staff and the area’s only SPECT/CT scanners.
Candidates for DaTscan are patients referred by their primary care physician or neurologist who present symptoms similar to those found with Parkinson’s disease, but after undergoing other diagnostic evaluations, have yet to be definitively diagnosed by a physician. Total testing time is four to five hours. The test is covered by most insurances and Medicare.
By Thomas J. Yuschok, MD
Thomas J. Yuschok, MD, is Chief of Nuclear Radiology for Halifax Health. He is certified by the American Board of Radiology and has special competence in nuclear radiology as well as a certification by the Board of Nuclear Cardiology. Dr. Yuschok is a graduate of Pennsylvania State University College of Medicine and performed his residency at the University of Florida.