Indirect MR arthrography of the knee - Effects of low-intensity ultrasoundon the diffusion rate of intravenously administered Gd-DTPA in healthy volunteers

RATIONALE AND OBJECTIVES. To evaluate whether application of low-intensity ultrasound may increase the diffusion rate of intravenously administered ga dopentetate dimeglumine (Gd-DTPA) and increase the amount of joint fluid on indirect magnetic resonance (MR) arthrography. METHODS. Conventional MR imaging, indirect MR arthrography, and power Doppl er ultrasonography were per-formed before and after application of therapeu tic, pulsed low-intensity ultrasound in 12 asymptomatic knees of 12 volunte ers. Intra-articular diffusion of intravenously administered Gd-DTPA as mea sured by signal intensity differences of the intraarticular joint fluid bef ore and after ultrasound treatment was assessed. In addition, the amount of joint fluid was rated, and differences in synovial blood flow as evidenced by power Doppler ultrasonography were noted. RESULTS. All volunteers tolerated well the application of therapeutic low-i ntensity ultrasound. A significant increase in intra-articular diffusion of intravenously administered Gd-DTPA was noted in all knees, and an increase in joint fluid was noted in 8 of 12 knees (66.6%). Detection of power Dopp ler flow signal in the synovium of the suprapatellar recess was possible in one instance at posttreatment exam. CONCLUSIONS. Use of pulsed, therapeutic low-intensity ultrasound may increa se the diffusion rate of intravenously administered Gd-DTPA and may induce joint effusion.