RT Journal Article SR Electronic T1 Comparison of magnetic resonance angiography and 18F-fluorodeoxyglucose positron emission tomography in large-vessel vasculitis JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 1165 OP 1171 DO 10.1136/annrheumdis-2018-213102 VO 77 IS 8 A1 Kaitlin A Quinn A1 Mark A Ahlman A1 Ashkan A Malayeri A1 Jamie Marko A1 Ali Cahid Civelek A1 Joel S Rosenblum A1 Armin A Bagheri A1 Peter A Merkel A1 Elaine Novakovich A1 Peter C Grayson YR 2018 UL http://ard.bmj.com/content/77/8/1165.abstract AB Objectives To assess agreement between interpretation of magnetic resonance angiography (MRA) and 18F-fluorodeoxyglucose positron emission tomography (PET) for disease extent and disease activity in large-vessel vasculitis (LVV) and determine associations between imaging and clinical assessments.Methods Patients with giant cell arteritis (GCA), Takayasu’s arteritis (TAK) and comparators were recruited into a prospective, observational cohort. Imaging and clinical assessments were performed concurrently, blinded to each other. Agreement was assessed by per cent agreement, Cohen’s kappa and McNemar’s test. Multivariable logistic regression identified MRA features associated with PET scan activity.Results Eighty-four patients (GCA=35; TAK=30; comparator=19) contributed 133 paired studies. Agreement for disease extent between MRA and PET was 580 out of 966 (60%) arterial territories with Cohen’s kappa=0.22. Of 386 territories with disagreement, MRA demonstrated disease in more territories than PET (304vs82, p<0.01). Agreement for disease activity between MRA and PET was 90 studies (68%) with Cohen’s kappa=0.30. In studies with disagreement, MRA demonstrated activity in 23 studies and PET in 20 studies (p=0.76). Oedema and wall thickness on MRA were independently associated with PET scan activity. Clinical status was associated with disease activity by PET (p<0.01) but not MRA (p=0.70), yet 35/69 (51%) patients with LVV in clinical remission had active disease by both MRA and PET.Conclusions In assessment of LVV, MRA and PET contribute unique and complementary information. MRA better captures disease extent, and PET scan is better suited to assess vascular activity. Clinical and imaging-based assessments often do not correlate over the disease course in LVV.Trial registration number NCT02257866.