FDG-PET beats amyloid imaging for assessing Alzheimer’s

New research suggests that fluorodeoxyglucose (FDG) PET is better for assessing the severity of Alzheimer’s disease and mild cognitive impairment (MCI) than florbetapir-PET scans.

“Both florbetapir-PET and FDG-PET are approved diagnostic methods for Alzheimer’s disease, and both appear to be effective in indicating some sort of cognitive impairment. However, we have now shown that FDG-PET is significantly more precise in clinical studies, and it is also available for routine use with modest costs,” co-principal investigator Abass Alavi, MD, PhD, with the University of Pennsylvania, said in a prepared statement. “Our results support the notion that amyloid imaging does not reflect levels of brain function, and therefore it may be of limited value for assessing patients with cognitive decline.”

Alzheimer’s disease affects 5.8 million people in the U.S., and PET plays a central role in evaluating the condition, along with others, such as cognitive impairment, that often predicate Alzheimer’s. Recent research has called into question the effectiveness of amyloid imaging in monitoring these patients; new studies have shown amyloid plaques in healthy patients without dementia, while clinical trials have found the “intended” removal of amyloid had little impact in patients with Alzheimer’s.

For their study, the team analyzed 63 patients, 19 of whom had Alzheimer’s, 23 had MCZI and another 21 were healthy participants. Each underwent both FDG- and florbetapir-PET exams. Their level of cognitive impairment, if any, was assessed using a Mini Mental Status Examination (MMSE). Those scores were correlated to data generated from five regions of the brain using a novel global quantification approach.

Results revealed that each PET technique could separate dementia patients from the control group. But, after comparing MMSE scores, low cognitive performance and high amyloid levels had a weaker correlation than that of FDG and low cognitive scores for all participants. This, the authors wrote, indicates FDG-PET is a better overall indicator of cognitive decline.

“Amyloid imaging has a value in diagnosing or ruling out Alzheimer’s disease, but it’s a bit like all or nothing,” co-principal investigator Andrew Newberg, MD, a professor of radiology at Thomas Jefferson University, said in the same statement. “Our study shows that it can reveal disease, but you wouldn’t be able to differentiate between someone who had very mild or very severe symptoms.”

The full study was published July 12 in the Journal of Alzheimer’s Disease.