ABSTRACT
OBJECTIVES: To evaluate the ability of 18FDG PET/CT, at diagnosis of giant cell arteritis (GCA) and during follow-up, to predict occurrence of relapse in large-vessel GCA (LV-GCA). METHODS: We conducted a retrospective study using the French Study Group for Large-Vessel Vasculitis (GEFA) network. Data from patients with LV-GCA diagnosed by PET/CT and who had PET/CT in the following year were collected. For each PET/CT, PET vascular activity score (PETVAS) and total vascular score (TVS) were assessed, and their ability to predict the occurrence of subsequent relapse was assessed. RESULTS: A total of 65 LV-GCA patients were included, of whom 55 had undergone a follow-up PET/CT 3 to 12 months after the diagnosis of GCA. Patients for whom the second PET/CT (PET2) was performed during active GCA were excluded. PETVAS and TVS decreased between PET1 and PET2 in all patients (p < 0.001). There was no correlation between vascular activity scores in PET2 and time to prednisone taper. For relapse prediction, at PET1, the AUC of the TVS and PETVAS were respectively 51.9 and 41.9 at 6 months, 55.3 and 49.7 at 1 year, 55 and 55.7 at 2 years. For PET2, the AUC were respectively 46.1 and 46.7 at 6 months, 52.1 and 48.9 at 1 year, 58.4 and 52.3 at 2 years. CONCLUSION: PET vascular activity scores at diagnosis and at follow-up PET/CT performed outside a period of GCA activity do not display high performance to predict the occurrence of subsequent relapse in LV-GCA patients.
ABSTRACT
BACKGROUND: Prognosis data on giant-cell arteritis (GCA)-associated aortitis are scarce and heterogeneous. The aim of this study was to compare the relapses of patients with GCA-associated aortitis according to the presence of aortitis on CT-angiography (CTA) and/or on FDG-PET/CT. METHODS: This multicenter study included GCA patients with aortitis at diagnosis; each case underwent both CTA and FDG-PET/CT at diagnosis. A centralized review of image was performed and identified patients with both CTA and FDG-PET/CT positive for aortitis (Ao-CTA+/PET+); patients with positive FDG-PET/CT but negative CTA for aortitis (Ao-CTA-/PET+), and patients solely positive on CTA. RESULTS: Eighty-two patients were included with 62 (77%) of female sex. Mean age was 67±8 years; 64 patients (78%) were in the Ao-CTA+/PET+ group; 17 (22%) in the Ao-CTA-/PET+ group and 1 had aortitis only on CTA. Overall, 51 (62%) patients had at least one relapse during follow-up: 45/64 (70%) in the Ao-CTA+/PET+ group and 5/17 (29%) in the Ao-CTA-/PET+ group (log rank, p = 0.019). In multivariate analysis, aortitis on CTA (Hazard Ratio 2.90, p = 0.03) was associated with an increased risk of relapse. CONCLUSION: Positivity of both CTA and FDG-PET/CT for GCA-related aortitis was associated with an increased risk of relapse. Aortic wall thickening on CTA was a risk factor of relapse compared with isolated aortic wall FDG uptake.
