Role of duplex Doppler and power Doppler sonography in transplanted kidneys with acute renal parenchymal dysfunction

The limited work published on the comparison of power Doppler sonography (PDS) and duplex Doppler sonography (DDS) in the assessment of acute renal allograft dysfunction has shown contradictory results. We compared the role of DDS and PDS in renal transplant recipients developing acute renal parenchymal dysfunction and correlated these findings with kidney biopsy, which was taken as the gold standard. Thirty post-renal transplant patients with acute graft dysfunction underwent Doppler sonography, DDS and PDS using an HDI 5000 ATL machine. Patients who developed graft dysfunction as a result of vascular, obstructive or other non-parenchymal causes were excluded. All patients underwent an allograft biopsy within 72 h of the sonography. Based on the biopsy findings, 24 patients were categorized as having acute rejection, and six patients as having no rejection. The overall sensitivity, specificity and accuracy of DDS for evaluation of graft dysfunction were 54.17, 33.33, and 50.00%, respectively, and that for PDS were superior with 87.50, 33.30, and 76.67%, respectively. The low specificity can be partially attributed to the small number of cases without rejection in our study population. We conclude that PDS is superior to DDS in screening patients with acute parenchymal renal dysfunction post-transplant. However, a normal PDS examination does not exclude the presence of acute rejection. Power Doppler sonography is a useful screening test for diagnosing acute rejection but a renal allograft biopsy remains the gold standard for diagnosis of this condition.