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Accuracy of Duplex Ultrasonography in Identifying Transplant Renal Artery Stenosis
Mandy R. Maness, MD, Rachel L. Williams, MD, Jill N. Zink, MD, Daniel Torrent, MD, Charles S. Powell, MD, william M. Bogey, MD, Frank M. Parker, DO, Michael C. Stoner, MD.
East Carolina Heart Institute, Greenville, NC, USA.
Objectives:
The purpose of this study is to identify ultrasound criteria indicative of a flow limiting transplant renal artery stenosis (TRAS), using catheter-based arteriography as a gold standard.
Methods:
Over a 12-year period, ultrasound and arteriographic images were reviewed and pertinent sonographic variables collected. Univariate analysis and receiver-operator curve techniques were utilized to evaluate these parameters, with a P > 0.05 indicating significance.
Results:
Nineteen renal transplant patients were identified for inclusion, of these 9 were found to have flow limiting stenosis defined as a >70% luminal narrowing by arteriography (Table). All patients with TRAS underwent catheter-based intervention. Correlates of TRAS were renal artery peak systolic velocity (PSV) and renal:iliac PSV ratio. A PSV > 4 m/s was found to correlate positively with stenosis (sensitivity 70%, specificity of 80%, P=0.01). A renal:iliac PSV ratio > 1.5 yielded, sensitivity of 66.7% and specificity of 80%, P=0.04. When either variable was positive (composite PSV), the likelihood of a stenosis was increased (sensitivity 89%, specificity 70%, P=0.01).
Conclusions:
Duplex ultrasound is a reliable method for identifying TRAS, making this modality useful as a screening exam. PSV and the renal:iliac PSV were found to be accurate for the determination of TRAS in our laboratory. Acceleration time was not a reliable indicator of stenosis. The divergence of these data from commonly cited thresholds attests to the importance of individualized laboratory standards and quality control to optimize the care of renal transplant patients.
Summary of Ultrasound Parameters | TRAS + (n=9) | TRAS - (n=10) | p value | | Iliac PSV (m/s) | 3.07+/-0.66 | 2.99+/-0.30 | 0.90 | | Renal PSV (m/s) | 4.99+/-0.48 | 3.38+/-0.44 | 0.03 | | Renal PSV > 4 m/s (%) | 77.8 | 20 | 0.01 | | Iliac:Renal PSV | 2.57+/-0.89 | 1.15+/-0.17 | 0.16 | | Iliac:Renal PSV>1.5 (%) | 66.7 | 20 | 0.04 | | Acceleration Time | 126.7+/-16.3 | 111.3+/-13.7 | 0.49 | | Resistive Index | 0.80+/-0.04 | 0.84+/-0.02 | 0.48 | | Composite PSV (%) | 88.9 | 30 | 0.01 |
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