Complete Metabolic Remission on PET/CT Following Glucocorticoids Monotherapy in Giant Cell Arteritis-related Large-Vessel Involvement

Objectives: To evaluate the proportion of patients with giant cell arteritis (GCA)-related large-vessel involvement (LVI) with a complete metabolic remission on PET/CT after treatment with glucocorticoids (GC) only.Methods: This retrospective multicenter cohort enrolled GCA patients with LVI diagnosed on PET/CT. Each patient underwent at least a second PET/CT >3 months after the first procedure and was treated only with GC. Our primary endpoint was the proportion of patients with complete metabolic remission on the second PET/CT.Results: Among the 75 enrolled patients, 32 (43%) showed a complete metabolic remission at last follow-up. The second PET/CT was performed 8 [5-11] months after the initial PET/CT. Among the 32 patients, 16 were weaned off GC with a follow-up >12 months after the negative PET/CT. Among the 43 patients without metabolic remission, 19 showed stable or increased vascular uptake at follow-up, and 24 had persistent PET/CT positivity with fewer involved vascular territories. At last follow-up (median: 51 [27-93] months), 66 and 56% of patients with and without metabolic remission, respectively, had discontinued GC. Two patients showed LVI relapse on a third PET/CT. Of the 34 patients with available data regarding aorta morphology during follow-up, 8 developed an aortic dilation, and all of them had persistent positive PET/CT (log-rank: p < 0.05).Conclusion: A complete metabolic remission on PET/CT was observed in 43% of GCA patients with LVI treated with GC alone. Aortic dilation exclusively occurred in patients with persistent positive PET/CT.