Clinical use of renal perfusion imaging by means of harmonic sonography with a microbubble contrast agent in patients after renal transplantation: Preliminary study

Abstract

Objective. The purpose of this research was to determine the feasibility of renal perfusion imaging by means of harmonic sonography with a microbubble contrast agent for the evaluation of renal perfusion after renal transplantation compared with technetium Tc 99m diethylenetriamine pentaacetic acid ( 99mTc-DTPA) scans. Methods. During a 10-month period, 100 patients with renal transplantation that included normal perfusion (n = 68) and delayed perfusion including chronic rejection (n = 19), acute rejection (n = 9), arterial stenosis (n = 2), and urinary stricture (n = 2) underwent sonographic renal perfusion imaging and 99mTc-DTPA scans. Sonographic images were obtained every 3 seconds for a total of 3 minutes after administration of a bolus injection of 4 g of the microbubble contrast agent at a concentration of 300 mg/mL. Sonographic renal perfusion images were converted into a renal perfusion curve, and the calculated time at the peak of the curve (T peak) was compared with that of the 99mTc-DTPA scan. Results. The Tpeak with the 99mTc-DTPA scan was 14.9 seconds in the normal group and 33 seconds in the delayed perfusion group. The Tpeak on sonographic renal perfusion images was 25 seconds in the normal group and 44.8 seconds in the delayed perfusion group. Sonographic renal perfusion images showed good correlation with the 99mTc-DTPA scan (r = 0.74; P = .0001). The cutoff value of the Tpeak on sonographic renal perfusion images was 35 seconds (sensitivity = 85%; specificity = 90%). Conclusions. The renal perfusion images obtained by means of harmonic sonography with a microbubble contrast agent constitute an effective sonographic technique for the evaluation of renal perfusion abnormalities after renal transplantation compared with a 99mTc-DTPA scan. © 2005 by the American Institute of Ultrasound in Medicine.