¹⁸F-FDG-PET/CT: an accurate method to assess the activity of Takayasu's arteritis

The objective of the study is to investigate the value of ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) for assessment of the activity of Takayasu's arteritis (TA) and the correlation between acute-phase reactive proteins (ARPs) and standard uptake value (SUV). Analyses of the clinical characteristics and 42 ¹⁸F-FDG-PET/CT scans in 39 TA patients were undertaken. The degree of FDG uptake in the blood vessel walls was assessed quantitatively by SUV. TA activity was analyzed by physician global assessment (PGA). Clinical and ¹⁸F-FDG-PET/CT characteristics were compared between patients with clinically active and clinically inactive TA. Maximum SUV (SUV_max), mean SUV (SUV_mean), and SUV ratio (SUV_ratio) were significantly higher in the clinically active group than in the clinically inactive group (3.63 ± 1.96 vs. 1.82 ± 0.43, p = 0.007; 2.07 ± 0.71 vs. 1.43 ± 0.32, p = 0.009; 2.08 ± 1.17 vs. 0.95 ± 0.19, p = 0.000). Analyses of receiver operating characteristic (ROC) curves revealed a cutoff value of SUV_max of 2.21, with sensitivity and specificity of 86.2 and 90.0%, respectively, for clinically active TA. The SUV_ratio cutoff was 1.27 with a sensitivity and specificity of 79.3 and 100.0%, respectively. SUV_ratio was slightly superior to SUV_max and ARPs in the area under the curve (AUC) comparison. SUV_max and SUV_ratio showed a significant increasing trend with increasing US National Institutes of Health (NIH) score and levels of ARPs, interleukin-6, and serum amyloid-A protein. ¹⁸F-FDG-PET/CT is a promising non-invasive, quantitative measurement with high sensitivity and specificity for determining TA activity.