Comparison of [18F]fluorodeoxyglucose and [68Ga]Gallium DOTA-TATE in patients with active giant cell arteritis

Purpose [F-18]Fluorodeoxyglucose (FDG) is widely used in PET/CT imaging to detect large vessel vasculitis in giant cell arteritis (GCA), but its performance is suboptimal in patients receiving glucocorticoids. We aimed to compare [Ga-68]Ga-HA-DOTA-TATE, a somatostatin 2-analogue tracer, to [F-18]FDG in a pilot study of patients with GCA. Methods Eight patients with active GCA were prospectively, sequentially scanned with both [F-18]FDG PET/CT and [Ga-68]Ga-HA-DOTA-TATE PET/CT imaging. Images were evaluated by 2 blinded nuclear medicine specialists. Tracer uptake was assessed in 8 vascular territories using SUVmax, and target-background ratios (TBR) were calculated using both right atrium (TBRRA) and liver mean (TBRliver). Mean SUVmax and TBR of individual vascular territories and index vessels were compared. Results The patient median age was 71.5 years (range 64-82), and 4 (50%) were women. Active vasculitis (>= grade 2 visual uptake in large vessels) was present in 62.5% of [F-18]FDG scans. [F-18]FDG scans had higher RA background activity than [Ga-68]Ga-HA-DOTA-TATE (mean RA SUVmean 1.88 vs. 0.36, p < 0.001), while [Ga-68]Ga-HA-DOTA-TATE had a significantly higher liver uptake (mean liver SUVmean 7.54 vs. 2.39, p < 0.001). Vascular uptake (as measured by both SUVmax and TBRliver) was significantly higher in [F-18]FDG than [Ga-68]Ga-HA-DOTA-TATE scans in every vascular territory (p < = 0.05 for all comparisons), including index vessels (SUVmax 4.04 vs. 1.91, p = 0.01, TBRliver 1.73 vs. 0.27, p < 0.001). Conclusion In this pilot study of patients with active GCA, the arterial uptake of [Ga-68]Ga-HA-DOTA-TATE was lower and less conspicuous compared to [F-18]FDG. While further evaluation in larger cohorts is needed, a clear advantage of [Ga-68]Ga-HA-DOTA-TATE over [F-18]FDG for detecting vascular inflammation in GCA was not identified.