Kate Johnson

June 24, 2015


BALTIMORE — In patients with indeterminate traditional fluorodeoxyglucose (FDG)-PET scans, early amyloid PET could lead to earlier treatment, and the preservation of cognitive function, in up to one-sixth of patients, new research suggests.

"As of now, Medicare is not paying for amyloid scans; therefore, physicians are not regularly referring patients for these studies," lead researcher Erica Parker, a medical student at the University of California, Los Angeles, told Medscape Medical News.

"By acquiring an amyloid imaging scan within a month of an indeterminate FDG-PET, managing physicians can treat patients with an Alzheimer's-like pattern of reduced brain metabolism, improving the chance of preserving cognitive function," she told reporters here at the Society of Nuclear Medicine and Molecular Imaging 2015 Annual Meeting.

Using data from two studies — the Metabolic Cerebral Imaging in Incipient Dementia study and the Alzheimer's Disease Neuroimaging Initiative study — the researchers demonstrated that 40% of patients who underwent an amyloid scan after an indeterminate traditional FDG-PET scan received medication for Alzheimer's disease earlier than patients who did not. Of these, 17% experienced significant preservation of cognitive function (P = .0004), Parker reported.

The study involved 100 patients with mild cognitive impairment who had undergone baseline FDG-PET and amyloid scans. The scans — rated independently by a radiologist and a nuclear medicine physician — were classified as positive, negative, or indeterminate for neurodegenerative disease.

Amyloid imaging may become more widely used, given the clinical implications.

Of the 100 FDG-PET scans, 64 were rated as positive, 19 were negative, and 17 were indeterminate. Over 2 years, 14 (82%) of the patients with indeterminate scans showed progressive cognitive decline on the Mini-Mental State Exam, Clinical Dementia Rating, or both.

Half of the patients with cognitive decline had positive amyloid scans.

"Amyloid imaging may become more widely used, given the clinical implications for patients with an indeterminate FDG-PET scan," Parker concluded.

"Although the usefulness of amyloid imaging agents is being worked out, the results of this study provide a framework of one of the circumstances when amyloid imaging may be considered in order to improve patient outcomes," she explained.

Ms Parker has disclosed no relevant financial relationships.

Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2015 Annual Meeting: Abstract 191. Presented June 8, 2015.


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