Not the Teacher's PET: How Not to Diagnose Alzheimer Disease

Clinicians may choose to obtain several tests during the evaluation of an individual with dementia, including a positron emission tomography (PET) scan. These investigators, who work in a tertiary care neurobehavior clinic, aimed to determine the benefit of using this modality for dementia evaluations by reviewing the records of 46 patients who had received PET scans before being referred to their clinic.

Outside clinicians' interpretations of PET scans and the authors' consensus diagnoses differed in 65% of cases. Of the 22 false-positive interpretations of Alzheimer disease (AD) on PET scan, the authors diagnosed frontotemporal dementia (9%), psychiatric diagnoses (27%), normal findings (9%), and other diagnoses (54%; e.g., B₁₂ deficiency,…