FDG-PET in Large Vessel Vasculitis

Abstract

[18F]FDG-PET, a non-invasive metabolic imaging technique, is based on the regional distribution of fluorine-18-fluorodeoxyglucose ([18F]FDG) reflecting increased glucose consumption of tissues. This technique has become increasingly important over the years in the management of patients with malignancies, as many malignant tumors show an enhanced glucose metabolism1. [18F]FDG uptake in infections and other inflammatory changes seen during oncologic imaging showed indications for the versatility of [18F]FDGPET. Activated leukocytes also overexpress glucose transporters and avidly accumulate glucose and [18F]FDG 2,3, providing an important rationale for its use in vasculitis. Remarkable images of patients with active vasculitis have been generated through [18F]FDGPET scans4-12. Such images demonstrate the potential of [18F]FDG-PET for a variety of applications which implies that it may also be useful in the future for the routine evaluation of patients with several forms of vasculitis, particularly for large vessel vasculitis. The family of vasculitides is categorized with reference to the size of vessels involved into large, medium, and small vessel vasculitis (Table 1). Of interest with respect to [18F]FDGPET imaging is the group of large vessel vasculitides (giant cell arteritis and Takayasu’s arteritis), other causes of aortitis and potentially also chronic periaortitis. Patients of both of these diseases regularly present a set of non-specific symptoms and laboratory tests which make their diagnosis and follow-up quite challenging. Consequently, patients may receive delays or even unsuccessful diagnostic work-up regarding their condition. The use of whole-body scanning via [18F]FDG-PET may provide a sensitive metabolic imaging modality that could lead to a more successful and shorter diagnostic workup. The total amount of available data on [18F]FDG-PET in large vessel vasculitis is however still limited (Table 2). In addition, no standardized guidelines are in place for the placement of [18F]FDG-PET imaging in the sequence of the diagnostic workup, its performance, interpretation and description. This chapter summarizes current clinical data in order to assist nuclear medicine and rheumatology practitioners in recommending, performing and interpreting the results of [18F]FDG-PET in patients with suspected large vessel vasculitis.