CHICAGO - European researchers said the use of a new nuclear imaging agent dramatically improves the ability to diagnose which patients with early signs of tremor have Parkinson’s disease.
“Currently, the clinical diagnosis of Parkinson's disease provides only 80% sensitivity and 30% specificity,” said Dr. David Tuite, senior resident and lead researcher of the ongoing study at the Adelaide & Meath Hospital in Dublin, Ireland. “But we can improve that to 98% sensitivity and 97% specificity using DaTSCAN with single photon emission computed tomography (SPECT).”
Tuite studied DaTSCAN, generically the radiopharmaceutical I123-FP-CIT, in 50 patients with early stage tremor. The patients were referred to Tuite because neurologists were unable to determine if the patients had Parkinson’s disease or another disorder based on clinical observation and standard tests.
Tuite said that when the radioisotope was injected into the patients, those with Parkinson’s disease showed abnormal brain activity; specifically, the loss of dopamine in the putamen that occurs early in patients suffering from Parkinson’s disease. This enabled Tuite to determine that 45 of the 50 patients had Parkinsonism and not the less debilitating essential tremor.
“The real importance of doing these scans for Parkinson’s disease is that people want to know what they’ve got,” said Dr. William Strauss, professor of radiology at Weill Medical College of Cornell University. “In addition, there is some evidence now that early treatment for people with Parkinson’s disease might be able to slow progression. The scans offer very sensitive and specific information and can tell the patients whether they have a problem or don’t have a problem.”
In addition to improving the sensitivity and specificity of the diagnosis, Tuite said the enhanced images correlate completely with which side of the body is affected and provides an objective assessment of patients exhibiting Parkinson’s-like symptoms.
He said the specific diagnosis could be helpful in determining how patients should be treated. He said the accurate diagnosis would also allow for more specific treatment of those with essential tremor, which can be controlled with beta blocker therapy.
“This new agent will be especially useful in diagnosing patients with difficult clinical scenarios.More and more we are scanning people to resolve clinical uncertainty and to confirm the correct diagnosis,” Tuite said.
Not yet available in the United States, the image-enhancing agent can potentially be used in any hospital with standard nuclear medicine capability. It is produced by Amersham of the Netherlands.
“DaTSCAN imaging of the corpus striatum provides an objective assessment of the tremulous patient,” Tuite said. “Its high sensitivity and specificity far outstrip that of clinical examination and allows proper diagnosis of Parkinson's syndrome, even in difficult clinical scenarios.”
By Edward Susman
AuntMinnie.com contributing writer
December 4, 2002
Copyright © 2002 AuntMinnie.com
