Ultrafast Doppler Imaging for Early Detection of Synovitis in Rheumatoid Arthritis

Objective: Current medical ultrasound systems possess limited sensitivity in detecting slow and weak blood flow during the early stages of rheumatoid arthritis (RA), leading to potential misdiagnosis. Ultrafast Doppler is capable of detecting slow and weak flow. This study was aimed at evaluating the diagnostic value of ultrafast Doppler for RA. Methods: Thirty-three RA patients (19 established, 14 early stage) and 15 healthy participants were enrolled. A programmable imaging platform with ultrafast Doppler capability was used. The benchmark was a clinical system with conventional Doppler imaging. Standardized dorsal long-axis scanning of both wrists was performed. Both ultrafast and conventional power Doppler (PD) images were quantitatively analyzed with computer assistance and semiquantitatively scored with the Outcome Measures in Rheumatology (OMERACT) scoring system. Results: Ultrafast PD revealed more blood area than conventional PD in both RA wrists and healthy wrists. Ultrafast PD OMERACT was positive in 65 of 66 RA wrists and 26 of 30 healthy wrists (sensitivity [SEN] = 0.985, accuracy [ACC] = 0.719), while conventional PD OMERACT was positive in 28 of 66 RA wrists and 0 of 30 healthy wrists (SEN = 0.424, ACC = 0.604). Ultrafast PD revealed a higher synovial PD area, dilated vessels and PD brightness in RA wrists. Peak synovial PD brightness had the best diagnostic value for RA (area under the receiver operating characteristic curve = 0.802, SEN = 0.909, ACC = 0.813). For early-stage RA patients, ultrafast peak synovial PD brightness had higher sensitivity and accuracy than conventional PD indexes. Conclusion: Ultrafast PD had an increase of 0.561 in sensitivity and 0.209 in accuracy when compared with conventional PD. With its high sensitivity, ultrafast PD can detect early synovitis and identify RA patients during the early phase.