Comparison of 18F-FDG PET Findings of Pegfilgrastim-Induced Aortitis With Other Types of Large-Vessel Vasculitis

To elucidate the PET/CT findings of pegfilgrastim-induced aortitis (PFIA) and compare them with those of other large-vessel vasculitis.We enrolled 45 patients diagnosed with the following: PFIA, n = 8; Takayasu arteritis (TA), n = 12; giant cell arteritis (GCA), n = 6; and immunoglobulin G4-related aortitis (IgG4-A), n = 19. Records of PET/CT performed before treatment initiation were collected. The aorta and its branches were divided into 16 anatomic regions. Presence of abnormal 18F-FDG uptake in each region was determined and measured.The 18F-FDG-positive areas of PFIA were distributed in the regions of the ascending aorta to the suprarenal abdominal aorta, cervical branches of the aorta, and external iliac arteries, similar to those of TA. However, TA had a higher proportion of 18F-FDG-positive areas than PFIA in almost all anatomic regions. These areas of GCA were widespread throughout the entire aorta and the upper and lower limbs, whereas those of IgG4-A were observed from the abdominal aorta to iliac arteries. SUVmax, SUVpeak, metabolic volume, and total lesion glycolysis were higher in GCA than in PFIA, TA, and IgG4-A.Pegfilgrastim-induced aortitis distribution on PET/CT was frequently observed in the aorta, cervical branches, and extra iliac arteries. The low proportion of 18F-FDG-positive areas in PFIA was different from that of TA, GCA, and IgG4-A. These findings may help identify and differentiate various aortitis types in clinical practice.