PET/CT is a reliable measure of disease activity in LVV, but does not predict future relapses

PET/CT showed a discriminating value in measuring disease activity in large-vessel vasculitis (LVV). This finding was consistent in giant cell arteritis (GCA) and Takayasu’s arteritis (TAK) subgroups. Therefore, PET/CT could be a reliable tool in the assessment of disease activity in LVV. Surprisingly, higher PET Vascular Activity Score (PETVAS) scores during clinical remission were not predictive of future relapses [1]. 

Disease activity assessment in LVV lacks validated biomarker-based scoring systems. PET/CT might be the imaging biomarker that is needed, as it has shown promising results in recent studies [2]. The current study assessed whether PETVAS can discriminate between clinically active and inactive LVV (both GCA and TAK) in a single-centre cohort study. Patients with radiographic evidence of LVV (n=100) were followed from 2007 until 2020 and received complete assessments (clinical, laboratory, imaging) at baseline, annually, and when relapse was suspected. PETVAS was calculated for each PET/CT scan and compared with the clinical examination of disease activity status.

Dr Elena Galli (University of Modena and Reggio Emilia, Italy) presented the results. During the study, 474 PET scans were performed. Logistic regression analysis demonstrated that higher mean PETVAS scores were associated with clinically active LVV (10.6) versus inactive LVV (4.4; OR 1.15; P<0.0001). The correct subdivision of active and inactive LVV patients was further confirmed by the following parameters (all P<0.001): mean prednisone dose (active 29.3 vs inactive 6.9 mg/day), mean erythrocyte sedimentation rates (active 55.5 vs inactive 20.3 mm/hour), mean C-reactive protein rates (active 5.5 vs inactive 0.7 mg/dL), and percentage of patients with ≥1 clinical symptom suggestive of active LVV (active 78.5% vs inactive 4%).

The discriminative value of PETVAS was consistent in the GCA (OR 1.12; P<0.0001) and TAK (OR 1.22;  P<0.0001) subgroups. The computed ROC curves demonstrated acceptable predictive values of PETVAS scores differentiating between clinically active and inactive patients in the total population (AUC 0.73) and in the GCA (AUC 0.70) and TAK (AUC 0.79) subgroups. Nevertheless, higher PETVAS scores during low clinical disease activity (255 observations in 81 patients, 34 detected relapses) were not associated with a higher risk of clinical relapse (HR 1.04; P=0.25). According to Dr Galli, this finding is not well understood and needs to be unravelled in future research. Such subclinical vascular changes certainly need careful consideration on the timing and implications of PET scanning in GCA.

1. Galli E, et al. The role of positron emission tomography/computed tomography (PET/CT) in disease activity assessment in patients with large vessel vasculitis. OP0069, EULAR 2021 Virtual Congress, 2–5 June.
2. Grayson PC, et al. Arthritis Rheumatol. 2018;70(3):439-49.

 

Copyright ©2021 Medicom Medical Publishers



Posted on 2 August 20213 August 2021