Are Temporal Artery Biopsy Findings Related to PET/CT Findings in Giant Cell Arteritis?

Background Two clinical subsets of giant cell arteritis have been identified with different histological and CT findings. However, PET/CT findings have not been compared with temporal artery biopsy (TAB). Objective The aims of this study were to describe clinical and histological findings in patients with giant cell arteritis according to the presence or absence of aortitis in PET/CT at the disease diagnosis, and to identify independent factors related to aortic involvement. Methods Patients were included and followed prospectively. Clinical symptoms and TAB findings were recorded. PET/CT was performed in the first 10 days of steroid therapy. Aortitis was defined if a grade 3 uptake on visual analysis was present on arterial wall. Clinical and histological variables were compared according to the presence or absence of aortitis on PET/CT. Multivariate analysis was performed to identify independent factors related to the presence of aortitis. Results Twenty-seven patients (median age, 77.6 years) were included. PET/CT was performed with a median delay of 5.0 days. Aortitis was observed in 8 patients. Patients with aortitis were younger (69.9 vs 83.7 years, P = 0.04) and had less frequently ischemic manifestations (25.0% vs 84.2%, P = 0.006) than patients without aortitis. Giant multinucleated cells were more frequent on TAB from patients with aortitis (71.4% vs 16.7%), and its presence was an independent risk factor for the occurrence of aortic involvement on PET/CT (odds ratio, 12.2; P = 0.046). Conclusions Our study shows that giant cells on TAB are associated with the presence of aortitis on PET/CT. Patients with aortic involvement are younger and show less frequently ischemic manifestations.