Get the Picture: RheumMadness 2022 PET-CT in Large Vessel Vasculitis Scouting Report

Editor’s note: RheumMadness is the place for everyone crazy about rheumatology to connect, collaborate, compete and learn together. During RheumMadness, rheumatology concepts represent teams that compete against each other in a tournament, much like basketball teams do in the NCAA’s March Madness tournament. In a series for The Rheumatologist, readers will get a chance to read the scouting reports for each concept team. These reports are written by rheumatology fellows from 13 programs throughout the U.S.

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Region: Machines

Team: PET CT in Large Vessel Vasculitis

PET in LVV is the team to watch. A study by Grayson et al. from the U.S. National Institutes of Health forms our team’s solid foundation, with a single-center, prospective longitudinal cohort study evaluating ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in large vessel vasculitis (LVV) against a group of vasculitis-mimicking comparators.¹ Adult patients underwent FDG-PET combined with computed tomography (CT), and patients aged 18 and younger underwent whole body FDG-PET combined with magnetic resonance imaging (MRI).

In this study, 56 patients with LVV (30 with giant cell arteritis [GCA] and 26 with Takayasu arteritis) and 59 comparators (35 with hyperlipidemia, 17 with disease-mimicking LVV and 7 healthy controls) participated over a three-year period. During the study, each comparator underwent a single FDG-PET scan and each LVV patient underwent FDG-PET scan at entry and six-month intervals, with preceding clinical disease activity assessment by history, physical and laboratory evaluation.

In total, 111 FDG-PET scans were completed for 56 patients with LVV. Of the 40 patients with clinically active LVV, 34 had FDG-PET scans consistent with active vasculitis. Interestingly, 41 FDG-PET scans of the 71 patients with LVV in clinical remission were read as active vasculitis.¹

The non-LVV comparator group had 10 of 59 FDG-PET scans that read as active vasculitis, resulting in FDG-PET 85% sensitivity and 83% specificity in distinguishing clinically active LVV and specificity of 42% in distinguishing clinically active vs. remission LVV. Multivariate modeling showed a positive FDG-PET scan was more likely in clinically active disease, short disease duration, lower body mass index (BMI) and lower doses of prednisone.