18F-FDG-PET/CT in the evaluation and differential diagnosis of active large-vessel vasculitis. A prospective study

Introduction: Large-vessel vasculitis has non-specific clinical symptoms, which can delay the diagnosis. Early recognition and treatment of the disease can help to avoid late complications. ¹⁸ F-FDG-PET can detect the inflammation of the vessel wall in the early stage of the disease with high sensitivity. CT is used to localize vasculitis. Aim: To examine the performance of ¹⁸F-FDG-PET/CT in patients with suspected large-vessel vasculitis, during relapse and remission, focusing on disease activity and extent. Method: 43 patients were evaluated. They were classified according to the clinical questions: steroid-naive suspected vasculitis, suspected vasculitis on steroid treatment, patients with relapse and in remission. We examined 10 cancer patients in control. We carried out visual and quantitative analysis of the ¹⁸F-FDG uptake of vessel walls. During quantitative evaluation, we determined standardised uptake values (SUVmax) of vessel wall segments compared to liver. Results: We found active disease in 5 patients examined for primary diagnosis, moreover, in 5 patients with relapse. The disease involved 3 or more vessel segments in fifty percent of the active cases. In the visually active group, the SUVmax was significantly lower in patients on steroid treatment than in steroid-naive cases (1.17 ± 0.11 vs. 1.43 ± 0.29; p = 0.005). We confirmed remission in 2 cases after therapy. In the inactive group, we found other types of inflammatory disorders in 8 cases. Conclusion: ¹⁸F-FDG-PET/CT is an effective diagnostic tool for large-vessel vasculitis, and can be used to determine the activity and extent of the disease. Steroid treatment influences the ¹⁸F-FDG-uptake of vessel wall. Orv Hetil. 2020; 161(20): 829-838.