In preliminary results from a three-country randomized trial, researchers reported finding a correlation between MRI signs and the clinical symptoms seen in patients with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP).
The two conditions, subsets of Parkinson's disease, have earned a reputation among neurologists as notoriously difficult to differentiate based on clinical findings alone.
"Both of these diseases are severe, with a rapid progression," said Dr. Yan Rolland, a radiologist at the University of Rennes, France. "MRI indicators of PSP and MSA have historically been poorly identified, mainly because few controlled studies have been performed, and existing studies have relied on nonstandardized MRI acquisition."
The Neuroprotection Natural History in Parkinson Plus Syndromes Trial involves 766 patients at 52 centers in the U.K., France, and Germany. The goal of the trial is to determine the usefulness of routine MR imaging for positive and differential diagnosis of PSP and MSA.
All enrolled patients received an MR exam, which was interpreted by a neurologist and a radiologist. The MR scans were also rated according to a quantitative scale involving 32 items and correlated with a clinical evaluation of Parkinson's, pyramid, cerebellar, ocular motor, dysautonomic, and cognitive signs and symptoms.
A reliability assessment for the first 300 patients showed moderate agreement for most items on the quantitative scale, Rolland said. All MR scans showed brain abnormalities.
MR imaging demonstrated a positive predictive value of 87% for MSA and 82% for PSP with clinical diagnosis, he said.
For MSA, high correlation was seen between cerebellar signs and symptoms and putamen abnormalities. For PSP, correlations were notable between ocular motor signs and symptoms and the mesencephalon.
"We believe this is the first time a significant correlation has been made between radiological signs and clinical symptoms in PSP and MSA," Rolland said. "Our final result will include neuropathologic correlation. But these results do indicate that MRI is useful in positively identifying and differentiating these diseases."
Other research has made note of the difficulty in arriving at a differential diagnosis for the two conditions. Imaging could play a role, said moderator Dr. Gordon Sze, chief of neuroradiology at Yale University.
"Now you have demonstrated this in a large group of patients, and it appears promising," he said.