News on the imaging of large vessel vasculitis

Large vessel vasculitis, including giant cell arteritis (GCA) and Takayasu arteritis (TAK), are autoimmune diseases primarily affecting the aorta and its branches. GCA is the most common primary vasculitis. Inflammatory changes in the vessel walls can cause serious complications such as amaurosis, stroke, and aortic dissection and rupture. Imaging techniques have become an integral part for the diagnosis and monitoring of large vessel vasculitis, allowing for effective disease monitoring. GCA and TAK exhibit similar patterns of vascular distribution. However, the temporal arteries are never involved in TAK, and axillary arteritis occurs more frequently in GCA. In most centers, ultrasound of the temporal and axillary arteries has replaced temporal artery biopsy as the primary diagnostic tool for GCA. In addition to ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and [18F]-FDG (fluorodeoxyglucose) positron emission tomography-computed tomography (PET) are important, particularly for visualizing the aorta. Moreover, PET-CT is now also capable of assessing the temporal arteries, although it is not yet widely available. In polymyalgia rheumatica (PMR), ultrasound of the shoulder and hip regions is part of the ACR/EULAR classification criteria. MRI allows detailed visualization of additional inflammatory extraarticular manifestations, showing characteristic inflammatory lesions in entheses, tendons, and ligaments. [18F]-FDG-PET-CT also enables the visualization of musculoskeletal inflammation, especially in the shoulder and hip regions, as well as paravertebral areas. Ultrasound can detect subclinical GCA in up to 23% of patients with PMR, which should be treated like GCA. Technological innovations such as new radiotracers and improved MRI imaging could further enhance the diagnosis and monitoring of large vessel vasculitis and PMR, thus playing a crucial role in improving the prognosis through faster initiation of therapy.