Positron emission tomography using the imaging tracer florbetaben can be used to reliably exclude the presence of amyloid in the brain of patients with dementia, according to a new study presented at the annual meeting of the American Academy of Neurology.
This means, according to study's authors, that a negative F-18 florbetaben (Neuraceq) scan lowers the probability that amyloid--which is a hallmark of Alzheimer's disease--is present and that Alzheimer's is contributing to the dementia.
In their study, researchers, led by Marwan Sabbagh--director of the Banner Sun Health Research Institute and research professor of neurology at the University of Arizona College of Medicine in Phoenix--looked at scans from 74 patients who had died and underwent a brain autopsy. The clinical diagnosis was that 55 patients had Alzheimer's, three had Lewy body dementia, eight had no dementia, and six had other kinds of dementias.
These scan assessments then were compared with the presence or absence of beta-amyloid plaques. They found that florbetaben 18 scans were correctly read as positive in 46 of 47 of the study participants, while scans from 24 of the 27 participants without amyloid were correctly ruled negative.
"We can absolutely say with over 95 percent certainty that if the scan is negative, the pathology is negative," Sabbagh told Medscape Medical News, adding that negative scans should encourage physicians to both look for options other than Alzheimer's as a cause of cognitive decline and to tailor treatment options, accordingly.
Three amyloid imaging agents now are approved by the U.S. Food and Drug Administration--Neuraceq, Vizamyl and Amyvid--but currently Medicare coverage is limited to research studies. The Centers for Medicare & Medicaid Services last year ruled against broader coverage, calling the evidence "insufficient" that PET beta-amyloid imaging improves outcomes for patients suffering from dementia or other neurodegenerative diseases.
In this case the researchers argued that the results provide more evidence that the use of PET beta-amyloid imaging can inform patient management and treatment.
"CMS cites the need to establish relevance and added value for clinical utility," Sabbagh told Molecular Imaging. "I as a dementia neurologist have ordered amyloid imaging and it informed me about the potential for the diagnosis and guiding care, decision making and treatment."