Conference Coverage

FDG–PET May Be the Strongest Predictor of Alzheimer’s Dementia in MCI


SAN DIEGO—Of the items in the most current Alzheimer’s disease diagnostic criteria, PET imaging with 18-fluorodeoxyglucose is the strongest individual positive predictive biomarker of short-term incident dementia in mild cognitive impairment (MCI), results from a multicenter analysis of 73 patients suggest.

“Since this was a relatively small population of patients, future studies are needed to confirm the results and to assess the incremental diagnostic value and cost-benefit ratio,” said Giovanni Frisoni, MD, at the 65th Annual Meeting of the American Academy of Neurology.

Dr. Frisoni, Deputy Scientific Director at the National Center for Alzheimer’s and Psychiatric Diseases in Brescia, Italy, and his associates conducted a secondary analysis of 73 patients with MCI who were treated at clinics in Brescia, Amsterdam, and Stockholm, to compare the prognostic accuracy of individual criteria in the two most current sets of diagnostic criteria for short- to mid-term incident Alzheimer’s dementia in patients with MCI: those published by an International Working Group (IWG) in 2007 and those published by the National Institute on Aging and the Alzheimer’s Association (NIA-AA) in 2011.

The patients were followed for an average of 39 months and a minimum of one year. They had a mean age of 66, and 57% were women. The investigators obtained data on biomarkers of amyloidosis (abnormal amyloid-beta-42 [A-beta-42] in CSF) and neurodegeneration (hippocampal atrophy on MRI measured with FreeSurfer software, temporo-parietal hypometabolism measured with 18-fluorodeoxyglucose [18-FDG]–PET, and abnormal tau protein levels in CSF).

“This is a pretty rare group of patients,” said Dr. Frisoni. The researchers compared positive and negative likelihood ratios of individual items in the IWG and NIA-AA criteria. During the follow-up period, 29 of the patients progressed to Alzheimer’s disease, and 44 remained stable, Dr. Frisoni reported. Among IWG criteria, positivity to any biomarker had the lowest negative likelihood ratio (0.00) for Alzheimer’s disease, while positivity to 18-FDG–PET had the highest positive likelihood ratio (5.82) and a low negative likelihood ratio (0.24).

Among NIA-AA criteria, positivity to neurodegeneration as measured by 18-FDG–PET, MRI, or CSF tau markers, regardless of amyloidosis status, had the lowest negative likelihood ratio (0.06), while positivity to A-beta-42 and 18-FDG–PET or A-beta-42 and hippocampal atrophy had the highest positive likelihood ratios (6.45 and 5.56, respectively).

—Doug Brunk
IMNG Medical News

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