The Role of FDG-PET in the Diagnosis and Monitoring of Large-Vessel Vasculitis

Giant cell arteritis (GCA) and Takayasu's arteritis (TAK) are the two main forms of large-vessel vasculitis (LVV), defined by inflammation of the aorta and its primary branches. Use of vascular imaging, including FDG-PET, has been increasingly incorporated into the assessment of patients with LVV. FDG-PET detects metabolic activity in the walls of the large arteries as a surrogate for vascular inflammation. In this article we review the use of FDG-PET to diagnose and monitor disease activity in different forms of LVV.

Use of FDG-PET to diagnose GCA by assessing vascular FDG uptake in the aorta and branch arteries is well-established. More recently, newer generation PET/CT scanners have also been used to assess metabolic activity in the cranial arteries, including the temporal arteries. In TAK, non-invasive angiography is used to assess for luminal damage at diagnosis, while FDG-PET can provide complementary information about whether active vascular inflammation is present. Recent studies have focused on the use of FDG-PET to monitor disease activity in LVV and the prognostic value of FDG-PET scans. Use FDG-PET in LVV remains an area of active ongoing research. While use at time of diagnosis in LVV has become well established, more studies are needed to evaluate the prognostic value of FDG-PET when monitoring disease activity in patients with LVV. Additional future directions for use of FDG-PET in LVV include employment of novel radiotracers, use of newer generation PET scanners, and incorporation into clinical trials to assess treatment response at the vascular level.