Quantitative analysis of vascularization in the finger joints in patients with rheumatoid arthritis using three-dimensional volumetric ultrasonography with power Doppler.

This study aimed to compare the intraobserver and interobserver reliability of three-dimensional (3D) and two-dimensional (2D) power Doppler ultrasonography (PDUS) and to assess the relationship between 3D PDUS and clinical parameters in patients with rheumatoid arthritis (RA). Bilateral second/third metacarpophalangeal joints and second/third proximal interphalangeal joints in 33 patients were examined by both 2D and 3D PDUS. Each joint was given a separate 2D PDUS subjective score (range, 0-3) in a standard manner. The 2D PDUS index is the sum of the scores of all eight joints assessed. 3D PDUS voxel signals were quantitatively analyzed by using computerized voxel counts. Intraobserver reliability was high for both examinations (2D PDUS: ICC = 0.957, 95% confidence interval = 0.818-0.999; 3D PDUS: ICC = 0.998, 95% confidence interval = 0.998-1.000). Interobserver reliability was also high (2D PDUS: ICC = 0.993, 95% confidence interval = 0.806-0.988; 3D PDUS: ICC = 0.999, 95% confidence interval = 0.999-1.000). A significant correlation was found between the 2D PDUS index and 3D PDUS voxel count (r = 0.795; p < 0.001). The 3D PDUS voxel count showed significant correlation with 28 joints Disease Activity Score (DAS28)-erythrocyte sedimentation rate (r = 0.448, p < 0.01) and DAS28-C-reactive protein (r = 0.383, p < 0.05). Our study indicates that the measurement of 3D PDUS may be a valuable tool for predicting disease activity.