Use of standardized uptake value ratios decreases interreader variability of [18F] florbetapir PET brain scan interpretation

Abstract

BACKGROUND AND PURPOSE: Fluorine-18 florbetapir is a recently developed-amyloid plaque positron-emission tomography imaging agent with high sensitivity, specificity, and accuracy in the detection of moderate-to-frequent cerebral cortical -amyloid plaque. However, the FDA has expressed concerns about the consistency of interpretation of [18F] florbetapir PET brain scans. We hypothesized that incorporating automated cerebral-to-whole-cerebellar standardized uptake value ratios into [18F] florbetapir PET brain scan interpretation would reduce this interreader variability. MATERIALS AND METHODS: This randomized, blinded-reader study used previously acquired [18F] florbetapir scans from 30 anonymized patients who were enrolled in the Alzheimer's Disease Neuroimaging Initiative 2. In 4 separate, blinded-reading sessions, 5 readers classified 30 cases as positive or negative for significant -amyloid deposition either qualitatively alone or qualitatively with additional adjunct software that determined standardized uptake value ratios. A coefficient was used to calculate interreader agreement with and without the use of standardized uptake value ratios. RESULTS: There was complete interreader agreement on 20/30 cases of [18F] florbetapir PET brain scans by using qualitative interpretation and on 27/30 scans interpreted with the adjunct use of standardized uptake value ratios. The coefficient for the studies read with standardized uptake value ratios (0.92) was significantly higher compared with the qualitatively read studies (0.69, P .006). CONCLUSIONS: Use of standardized uptake value ratios improves interreader agreement in the interpretation of [18F] florbetapir images.