Abstract

The large vessel vasculitides (LVV) include giant cell arteritis (GCA), which is frequently associated with polymyalgia rheumatica (PMR), Takayasu arteritis (TA) and chronic periaortitis (CP), an IgG4-related disease. In patients with GCA that involves the temporal arteries, performing a temporal artery biopsy will frequently demonstrate vasculitis. In the large thoracic vessel variant of GCA however, in TA and in CP, bioptic proof of vasculitis is hard to obtain, and we have to rely on imaging technologies to disclose vasculitis. In this presentation, the use of ultrasound imaging, CT-scanning, magnetic resonance imaging (MRI) and positron emission tomography (PET) in LVV will all be discussed, with major emphasis on the last modality. In patients with clinical pictures suggestive for GCA or TA, finding clearly increased FDG-uptake in the aortic wall and/or in the subclavian, carotid and/or axillary arteries, is almost diagnostic for these disorders. Patients with isolated PMR have increased FDG-uptake in the shoulders and hips, and half of them also in the processi spinosi of the cervical and lumbar spine. In patients with CP, intense FDG-uptake surrounding the abdominal and thoracic aortic wall can be found. In general, FDG-accumulations in LVV will decrease and eventually disappear during steroid treatment, although in some patients it may persist, probably due to vascular remodeling. There is no relation between the intensity of FDG-uptake and the probability of a future relapse. Other limitations of this technique are the fact that the temporal arteries themselves cannot be visualized - and hence PET scintigraphy will be negative in purely cranial forms of GCA – and that false positive vascular FDG-accumulation may also be caused by atherosclerosis, especially at the level of the iliac and femoral arteries. We are awaiting the results of a prospective study on PET and MRI in TA patients, while preliminary retrospective data that aortic FDG-uptake in the acute phase of GCA may be predictive for later aortic dilatation, need confirmation from a recently started prospective study.