SP0072 IMAGING IN THE DIAGNOSIS OF LARGE VESSEL VASCULITIS
Authors: Wolfgang Schmidt
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are large-vessel vasculitides (LVV). Recommendations demanded so far to confirm the diagnosis histologically, particularly in suspected GCA. Biopsy is however invasive, and results are not immediately available. Technology has rapidly improved; and many recent studies suggest that imaging may have comparable diagnosic accuracy. <h3>Objectives:</h3> To provide an overview of new developments for ultrasound, magnetic resonance imaging (MRI), computed tomography (CT) and 18-fluorodeoxyglucose positron emission tomography (PET) in diagnosis of LVV and to present new EULAR recommendations on imaging in LVV. <h3>Methods:</h3> A systematic literature review and meta-analysis of diagnostic and prognostic studies enrolling &gt;20 patients and investigating ultrasound, MRI, CT or PET in patients with suspected and/or established primary LVV was conducted (1). On this basis, a group of imaging experts, rheumatologists, patients and health care professionals developed EULAR recommendations on imaging in LVV (2). This review refers also to new data after the EULAR recommendations had been published. <h3>Results:</h3> In suspected GCA, imaging should be done early, but without delaying treatment. No further diagnostic test (histology or other imaging) is necessary if results of imaging and clinical presentation correspond. Ultrasound of temporal and axillary artery arteries showing a non-compressible 'halo-sign" is the method of first choice in suspected cranial GCA. The meta-analysis showed positive and negative likelihood ratios of 19 and 0.2, respectively, for a final diagnosis of GCA. Good data is also available on MRI of cranial arteries. Ultrasound, MRI, CT or PET can be applied for confirming extracranial GCA. Ultrasound is of limited value for assessing particularly the thoracic aorta. MRI is first choice for suspected Takayasu arteritis, but ultrasound, CT or PET can be also applied. Conventional angiography is not recommended instead for interventions. Imaging might be useful in suspected flare and to monitor damage. There is no convincing evidence to recommend routine monitoring in remission. Imaging should be done by a trained specialist using appropriate equipment. Particularly ultrasound of cranial arteries showed high diagnostic accuracy in a study for developing new classification criteria. Measuring intima thickness (cut-offs of around 0.4 mm for temporal and 1.0 mm for axillary arteries) may help to improve diagnostic accuracy and to use ultrasound for disease monitoring in trials (3). Reliabilities of sonographers both for evaluating videos and for examining patients directly were very high (4,5). Newer PET technology now allows to also show inflamed temporal, maxillary and vertebral arteries (6). The significance of positive imaging findings in follow-up studies still remains unclear. The incidence of vision loss decreased with the introduction of fast-track clinics. These clinics are increasingly established in centres. They include referral within one working day to a rheumatologist followed by immediate imaging for establishing the diagnosis. Imaging can be done by the rheumatologist (most commonly ultrasound) or by a collaborating department. <h3>Conclusion:</h3> Ultrasound, MRI, CT and PET allow to confirm or exclude LVV provided that it is performed by a trained specialist using appropriate equipment. Fast-track clinics using ultrasound are increasingly established in rheumatology. Ultrasound showed high diagnostic accuracy. Modern PET equipment may also delineate vasculitic temporal, maxillary and vertebral arteries. The significance of follow-up imaging studies in LVV still needs to be determined. <h3>References:</h3> [1] Duftner C, et al. RMD Open 2018;4:e000612 [2] Dejaco C, et al. Ann Rheum Dis 2018;77:636-42 [3] Schäfer VS, et al. Rheumatology 2017;56:1479-83 [4] Chrysidis S, et al. RMD Open 2018;4:e000598 [5] Schäfer VS, et al. J Rheumatol 2018;45:1289-95 [6] Nielsen BD, et al. Eur J Nucl Med Mol Imaging 2019;46:184-93 <h3>Disclosure of Interests:</h3> Wolfgang Schmidt Grant/research support from: GSK, Roche, Novartis, Sanofi, Consultant for: GSK, Roche, Novartis, Sanofi