Whole-body Dynamic [18F]FDG-PET/CT in Giant Cell Arteritis and Polymyalgia Rheumatica.

Objectives
We aimed to explore the diagnostic efficacy of whole-body dynamic (WBD) acquisition using [18F]-Fluorodeoxyglucose-positron-emission-tomography/computed-tomography ([18F]FDG-PET/CT) for the assessment of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) compared with the standard static PET/CT.Methods
Twenty-five patients with suspected GCA and/or PMR were prospectively enrolled in this single-center study. WBD PET imaging was performed before treatment using a standard PET/CT scanner with a multibed multipass dynamic whole-body acquisition approach (dPET). Reconstructed datasets were used to generate metabolic rate of [18F]FDG (MRFDG) images based on standard Patlak analysis. In case of pathologic FDG uptake, VOIs placed in vessel walls and joints were used for quantitation and definition of the target-to-background ratio (TBR): uptake in VOIs of vessel walls and joints (maximum values), to VOIs in blood pool (GCA), or to VOIs in normal muscles (PMR) (mean values). The final diagnosis based on the available imaging and laboratory results (except dPET), served as the standard of reference.Results
Seventeen of the 25 patients (68%) showed pathologic FDG uptake, of which 5 (20%) were finally diagnosed with GCA alone, 6 (24%) with PMR alone, and another 6 (24%) with both conditions. TBR difference between dPET and static PET was significant in both diseases(GCA P<0.003, PMR P<0.003), and TBRs of dPET and static PET were significantly higher in both diseases compared with the healthy controls.Conclusions
WBD [18F]FDG-PET/CT provided a significantly higher TBR in patients with GCA and PMR compared with standard static PET imaging. WBD [18F]FDG-PET/CT may potentially enhance the diagnostic accuracy in detecting GCA and PMR.