Comparative study of 18F-FDG PET/CT and CT angiography in detection of large vessel vasculitis.

Objective: Compare 18F-FDG PET/CT and CTangio in the diagnosis of extracraneal large vessel involvement in patients with suspicion of large vessel vasculitis (LVV).

Methods: A retrospective database reviewed 59 patients with clinical suspicion of LVV undergoing 18F-FDG PET/CT and CTangio. In 55 patients PET/TC and CTangio were done simultaneously in the same machine and in 4 patients with a scan interval of<1 month. PET/CT analyses included qualitatively and quantitative analysis (ratio SUVmax 18F-FDG vessel/SUVmax liver). CTangio was assessed for concentric mural thickening, contrast wall enhancement and structural vascular changes as potential complications of vasculitis.

Results: 18F-FDG PET/CT and CTangio show high specificity (97.2%) for LVV diagnosis, with an excellent sensitivity for 18F-FDG PET/CT (95.6%) and lower for CTangio (60.9%), which leads to a high negative predictive value for 18F-FDG PET/CT (97.2%) and a high false negative rate for CTangio (39.1%). A 70% concordance between 18F-FDG PET/CT and CTangio was obtained (Kappa index 0.70± 0.095 (P<.001).

Conclusions: The results show the greater potential of 18F-FDG PET/CT for the detection and extension of LVV. Therefore, 18F-FDG PET/CT should be exploited to the maximum and consider as the first line imaging technique in the extracranial diagnosis of LVV and its possible association with polymyalgia rheumatica. The addition of CTangio could be more indicated in patients with Takayasu arteritis and in long-standing and/or severe vasculitis since it increases the accuracy in the detection of possible vascular complications.