Benefits and challenges of 18F-FDG PET/CT in patients with Takayasu arteritis

AIM To evaluate the diagnostic performance of 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) in TA diagnosis and Takayasu arteritis (TA) activity assessment. MATERIALS AND METHODS This retrospective study included patients with TA diagnosed according to the American College of Rheumatology (ACR) criteria and undergoing 18F-FDG PET/CT imaging from October 2010 to July 2022. TA activity was assessed through 18F-FDG PET/CT (maximum standard uptake value [SUVmax], vascular SUVmax/mean standard uptake value [SUVmean] of liver (SUV ratio), and PET vascular activity score [PETVAS]) using physician global assessment (PGA) as the reference standard, and the results of these assessments were compared against the clinical activity scores (National Institutes of Health [NIH] and Indian Aortitis Disease Activity [ITAS-A] scores), acute-phase reactants (APR), and white blood cell and platelet counts. RESULTS Twenty 18F-FDG PET/CT examinations from 19 patients were included in the study, nine were performed in the active phase and 11 in the inactive phase. The involved vessels showed segmental and tubular FDG uptake in the active group. The average SUVmax, SUV ratio, and PETVAS was 6.3 ± 2.7 (range 3.4–12), 4.2 ± 1.7 (range 2.1–7.5), and 22.7 ± 11.2 (range 6–39), respectively, in the active group and 1.7 ± 0.9 (0.9–3.1), 1.1 ± 0.6 (range 0.6–2.4), and 3.5 ± 5.5 (range 0–18), respectively, in the inactive group. The sensitivity, specificity of SUVmax, SUV ratio, and PETVAS for TA activity assessment were 100%, 100%; 100%, 90.9%; and 88.9, 90.9%, respectively. After ROC curve analysis, a new SUVmax cut-off was obtained. Based on the new cut-off value, SUVmax 3.3 and SUV ratio 1.9 had a more perfect assessment performance. CONCLUSION 18F-FDG PET/CT is an alternative imaging technique for TA.