Power Doppler Imaging in Acute Renal Vein Occlusion and Recanalization: a Canine Model So-Young Yoo, MD1,2 In-One Kim, MD1 Young-Il Kim, MD1 Kyoung Ho Lee, MD1 Min Woo Lee, MD1 Byung Jae Youn, MD1 Woo Sun Kim, MD1 Kyung Mo Yeon, MD1 Index terms : Renal vein Renal vein thrombosis Power Doppler Ultrasonography DOI:10.3348/kjr.2008.9.2.128 Korean J Radiol 2008;9:128-133 Received June 12, 2007; accepted after revision July 16, 2007. 1Department of Radiology, Seoul National University College of Medicine, Seoul 110-744, Korea; 2Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea This study was supported by a grant from the Korea Health Industry Development Institute. Address reprint requests to: In-One Kim, MD, Department of Radiology, Seoul National University College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul 110-744, Korea. Tel. (822) 2072-3601 Fax. (822) 747-5781 E-mail: kimio@radcom.snu.ac.kr 128 Objective: To evaluate the dynamic changes of the power Doppler (PD) in acute renal vein occlusion and recanalization in a canine model. Materials and Methods: We performed a PD of the kidney during graded renal vein occlusion and recanalization induced by balloon inflation and deflation in nine dogs. The PD images were transferred to a personal computer, and the PD signals were quantified. Results: We observed the temporal change of the PD signal during renal vein occlusion and recanalization, with a decrease in the PD signal during occlusion and an increase during recanalization. The mean PD signal decreased gradually as the renal vein was occluded, and conversely increased gradually with sequen- tial relief of occlusion. The sequential change of the mean value of the PD signal was statistically significant. Conclusion: The PD can detect a change in renal blood flow during acute renal vein occlusion and recanalization in a canine model. The PD may be used as a helpful tool for the early detection of acute renal vein thrombosis and the monitoring of renal perfusion. U ltrasonography (US) has been used as a primary diagnostic modality for renal vein thrombosis (RVT), which is the most frequent renovascular disease in neonates and a major complication of the nephrotic syndrome (1, 2). The early diagnosis of RVT is especially important in children and younger patients, because it presents an acute problem, which is more favorably responded to, in the early treatment for younger age groups (2). The US findings associated with acute RVT include an enlarged echogenic kidney with poor corticomedullary differen- tiation. The echogenic filling defects can be seen in the renal vein or in the inferior vena cava (3, 4). However, conventional gray-scale and spectral Doppler (SD) have been shown to have a low sensitivity and specificity for the diagnosis of RVT, and only a limited role in early diagnosis prior to morphological changes of the kidney (5 7). A power Doppler (PD) is more sensitive than color Doppler (CD) for detection of blood flow. Recent development of this technique has made it possible to objectively quantitate the PD signal (8 10). However, the usefulness of PD for the diagnosis and monitoring of RVT has not been determined. The purpose of this study was to assess the feasibility of using a PD for the diagnosis and monitoring of RVT by evaluating the hemodynamic changes of the PD signal in complete or partial obstruction and recanal- ization of the renal vein in a canine model. Korean J Radiol 9(2), April 2008