A new diagnostic imaging technique, gives physicians the first objective test to evaluate patients for Parkinsonian syndromes, such as Parkinson’s disease. Northwestern Memorial Hospital is among the first institutions in the country to offer DaTscan™, the only FDA-approved imaging agent for assessment of movement disorders.
“The scan by itself does not make the diagnosis of Parkinson’s but it allows us to identify patients who have loss of dopamine, the major chemical responsible for the symptoms, from those who have no dopamine deficiency,” said Tanya Simuni, MD, a neurologist at Northwestern Memorial and director of Northwestern’s Parkinson’s Disease and Movement Disorders Center. “This is a very important step in being able to accurately identify and treat movement disorders and hopefully allow us to better understand these diseases over time.”
Parkinson’s disease is a neurodegenerative disorder that afflicts nearly 1.5 million Americans, with an additional 50,000 to 60,000 new cases identified each year. People with Parkinson’s lack dopamine in the brain, which leads to tremor, slowness of movement, muscle stiffness and balance problems. Clinical examinations, particularly early in the disease when symptoms are slight, can be inconclusive or lead to misdiagnosis of another movement disorder, such as essential tremor, which share similar symptoms to Parkinson’s, but require different treatment.
Developed by GE Healthcare, DaTscan is a substance used to detect the presence of dopamine transporters (DaT) in the brain. A patient is injected with the contrast agent and then undergoes a single-photon emission computed tomography (SPECT) scan. The test captures detailed pictures of the brain’s dopamine system and can provide visual evidence of the presence of dopamine transporters. Scans of patients with Parkinson’s disease or another parkinsonian syndrome will show very low dopamine levels. A SPECT scan examines brain function, rather than structure, and can show change in the brain’s chemistry.
“In Parkinson’s patients the brain’s anatomy remains largely normal, unlike other conditions such as stroke, where damage to the brain is visible,” explained Simuni, who is also an associate professor of neurology at Northwestern University Feinberg School of Medicine. “DaTscan attaches to dopamine neurons which illuminate on the SPECT scan; the more light areas that exist, the more healthy dopamine brain cells remain. If the areas of the brain that should show dopamine remain dark, it may indicate the patient has some type of parkinsonian syndrome.”
An accurate clinical diagnosis for patients with neurodegenerative movement disorders, such as Parkinson’s, can take up to six years. While symptoms often mimic Parkinson’s, other movement disorders, such as essential tremor, occur in different areas of the brain and do not involve the dopamine system.
Researchers are also hopeful that DaTscan will prove to be useful in following the progression of Parkinson’s throughout a patient’s lifetime. “The disease is clinically measured at certain points of time to help physicians understand its development,” said Simuni. “A lot of questions about how Parkinson’s disease progresses can be answered if DaTscan is able to show us changes in the brain’s chemistry over time.”
Source: Eurekalert (AAAS)