Assessment of Disease Activity in Takayasu Arteritis: A Quantitative Study with Computed Tomography Angiography.

BACKGROUND:Identifying disease activity in Takayasu arteritis (TAK) is challenging. This study aimed to investigate the value of quantitative characterization with computed tomography angiography in the assessment of disease activity in patients with TAK.METHODS:We retrospectively analysed the data on 162 aortic CT angiography from 140 TAK patients. Patients were categorized based on disease activity according to the National Institutes of Health criteria into two groups: active disease group (n = 65) and inactive disease group (n = 97).RESULTS:Patients with active TAK had a thicker wall compared with patients with inactive TAK (5.2 ± 2.4 mm vs. 2.5 ± 0.8 mm, p < 0.001). The relative post-contrast enhancement ratio of the thickened wall was higher in active TAK than in inactive TAK (1.5 ± 0.3 vs. 1.1 ± 0.2, p < 0.001). Given a thickness cutoff of 3.3 mm, sensitivity for active-phase TAK was 83.1%, specificity 89.7%, positive predictive value 84.4%, and negative predictive value 88.8%. With a relative post-contrast enhancement ratio cutoff of 1.2, sensitivity for active-phase TAK was 89.2%, specificity 76.3%, positive predictive value 71.6%, and negative predictive value 91.3%. In receiver-operating characteristic curves comparison, maximal wall thickness and relative post-contrast enhancement ratio were superior to C-reactive protein and erythrocyte sedimentation rate for determining active phase disease (p < 0.05).CONCLUSIONS:Quantitative characterization with CT angiography was a useful tool to assess disease activity in TAK patients. Maximal wall thickness and relative post-contrast enhancement ratio have a high sensitivity and specificity for detecting TAK activity.