(Ultrasound Review) A recent article published in the Journal of Clinical Ultrasound, found that duplex Doppler sonography was a superior screening tool for suspected renal artery stenosis (RAS) in transplant kidneys. The study objective was to determine the accuracy of Doppler ultrasound in assessing RAS, and ascertain which Doppler parameters most reliably diagnosed RAS.
According to investigators from the University of São Paulo in Brazil "transplant RAS is the major late vascular complication of renal artery transplantation." Previous research found "transplant RAS has been reported to affect 3-4 % of all renal transplants and to occur, on average, three years after surgery." The most common presenting symptom (93%) for transplant RAS is hypertension that does not respond to treatment.
Twenty-two patients with suspected RAS and 19 control subjects were studied over a three-year period. All patients underwent color Doppler sonography, MR angiography (MRA) and digital subtraction angiography (DSA). A renal artery diameter stenosis >50% was considered significant on MRA and DSA, and these results were used to divide patients into RAS and control groups.
Sonography was performed using an Aspen (Siemens Medical Solutions, Erlangen, Germany) with a 4-7 MHz curved array. Grayscale was used to assess transplant size and morphology. Using a Doppler angle kept at 30-60 degrees they evaluated "the ipsilateral iliac artery proximal and distal to the anastomosis, the renal artery, and the interlobar vessels of the upper, middle, and lower poles of the kidneys." The most accurate Doppler parameters were "an acceleration time of 0.1 seconds or higher in the renal and intrarenal arteries, a peak systolic velocity (PSV) of >200 cm/s in the renal artery, and a ratio of PSVs in the renal and external iliac arteries (RIR) of >1.8."
"The use of the acceleration time in the intrarenal artery alone or in combination with other parameters such as the PSV in the renal artery and the RIR for the detection of transplant RAS by color Doppler ultrasound reached a high level of accuracy," they concluded.
Duplex Doppler sonography of transplant renal artery stenosisde Morais, R. et al.
Center of Imaging Science and Medical Physics, faculty of medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
J Clin Ultrasound 2003 March/April; 31:135-141
By Ultrasound Review
June 6, 2003
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