Correlation of early-phase F-18 Florbetapir (AV-45) PET images to FDG images

Objectives PET images of 18F-FDG for cerebral glucose metabolism can provide complementary information to amyloid plaque images for diagnosis of AD, and possibly differentiating AD from other dementias. F-18 Florbetapir (AV-45) is a novel PET tracer for plaque pathology in AD. The goal of this study was to explore the perfusion-like property of early-phase AV-45 images, and compare the activity distribution to that of FDG images.

Methods Dual-time point PET scans were performed by acquiring two AV-45 images of 0-5min (early-phase) and 50-60 min (late-phase) after tracer injection in 4 AD and 3 normal controls. Each subject was also underwent both FDG and MRI scans. Early-phase and late-phase AV45 and FDG images were normalized to the MNI template, and 90 VOIs in the AAL template were applied for computing SUVR (standard uptake value ratio) of each VOI to mean value of cerebellum VOI for AV45 and FDG images. Correlation of SUVR in early-phase AV45 to the corresponding FDG was calculated for all pooled VOIs for all subjects.

Results Early-phase AV45 images showed similar distribution patterns as the corresponding FDG images. The SUVR correlation coefficient R^2 of the early-phase AV45 to FDG was 0.6848 for all subjects. A higher correlation of R^2 > 0.8 was observed in the AD group.

Conclusions Preliminary results showed that the distribution pattern of early-phase AV45 images were highly correlated with FDG images, and thus is potentially useful in providing complementary perfusion-like information to that of amyloid plaque density by late-phase AV45 images