Technical note: comparison of colour Doppler energy sonography with conventional colour Doppler sonography in detection of flow signal in peripheral renal transplant vessels.

The technical advantage of colour Doppler energy sonography (CDE) results in a higher sensitivity for blood flow detection than in conventional colour Doppler sonography (CDI). We compared the efficiency of CDE versus CDI in the detection of blood flow signals in asymptomatic patients after renal transplantation. 10 asymptomatic voluntary patients after renal transplantation were evaluated with CDI and subsequently with CDE by two examiners. Filter, scale and gate setting were kept constant, the Doppler gain was increased individually in every patient until background noise just did not derange the image. The assessment of blood flow signal was done using a self defined score system. CDI showed Doppler signal in the interlobar vessels in all 10 patients and blood flow signal in arcuate arteries and adjacent portions of interlobular vessels in nine of 10 patients. We were not able to detect blood flow related signal in the more peripheral medullary and cortical vessels. CDE obtained blood flow signal in interlobar and interlobular vessels in all patients. In addition, Doppler signal was observed in all patients in small medullary and cortical vessels. CDE increases detection of blood flow related signal in peripherally located small medullary and cortical vessels. There was no improvement in the evaluation of blood flow in interlobar vessels but marked improvement in blood flow detection in small peripherally located vessels. CDE cannot completely replace CDI in the sonographic evaluation of vascular complications in renal transplants, but should be used as an additional measure to rule out pathology in small peripheral renal vessels.