Renal Artery Stenosis With Color Doppler Ultrasound Evaluation

PartⅠEvaluation of Hemodanamic Parameters in the Diagnosis of Renal Artery StenosisObjectiveTo evaluate the characteristic of hemodynamic change of renal artery stenosis (RAS)(diameter reductions≥50%) and its diagnostic value.MethodsA study group was composed of 77 patients with 153 renal arteries that were detected by color Doppler flow imaging and were referred to renal arteriography afterwards. Five Doppler parameters,including renal peak systolic velocity(RPSV),renal aortic ratio(RAR),renal-renal ratio(RRR),renal-segmental ratio(RSR) and renal-interlobar ratio(RIR) were measured.Arteries were considered stenosed on renal arteriography if there was a diameter reduction of greater than 50%.Statistical analysis to determine the best parameter for predicting a RAS was performed with receive operating characteristic curves.The sensitivity,specificity,and negative predicting value,positive predicting value and accuracy at various cutoffs were calculated.ResultsIn the 153 main renal arteries demonstrated by renal arteriography,there were 6 occlusion and 68 stenoses(diameter reduction 50%～99%).Among the 68 stenoses,40 were caused by atherosclerosis,17 by Takayasu's arteritis,9 by fibromuscular dysplasia and 2 by other etiology.Doppler examination was technically successful in 98.7%of renal arteries(151/153).Receiver operating characteristic analysis showed that the RIR was the best parameter with 85.29%sensitivity,89.87%specificity and 87.76%accuracy.The best cutoffvalues for the 5 parameters(RPSV,RAR,RRR,RSR,RIR) were 170cm/s,2.3,2.0,4.0, 5.5,respectively.ConclusionsFor the detection of RAS(diameter reduction≥50%),the RIR is the best indicator in the five velocity parameters,and its diagnostic efficiency is only little higher than other most parameters.The RAR and RRR have worse sensitivity.Valuing the characteristic of hemodynamic change of renal artery and its influencing factors can improve diagnostic efficiency of RAS. PartⅡDifferentiations of tardus-parvus pattern between the atherosclerotic and non-atherosclerotic renal artery stenosisObjectiveTo evaluate the differences in tardus—parvus pattern between atheroscelrotic and non-atherosclerotic renal artery stenosis(RAS).MethodsA study group of 135 RAS patients confirmed by renal arteriography were examined by color Doppler sonography.These patients included 35 cases of Takayasu arteritis,29 cases of fibromuscular dysplasia and 71 cases of atherosclerosis.They were categorized into atheroscelrotic and non-atherosclerotic group,and each group were graded into mild,moderate,severe and occlusive subgroups.Doppler spectra of interlobar arteries were obtained,and the acceleration time(AT) and resistive index(RI) was recorded.ResultsRenal angiography revealed 31 moderate RAS,129 severe RAS,and 19 occlusions.No statistically significant difference was found in AT between the atherosclerotic and non-atherosclerotic groups in the mild(P=0.07),moderate(P=0.28) or severe stenotic subgroup(P=0.10).However,statistically significant differences were found in RI between the atherosclerotic and non-atherosclerotic groups in the mild(P＜0.001), moderate(P＜0.001) or severe subgroup(P＜0.001).ConclusionsThe measurement method of AT used widely at present can not differentiate possible differences in pulsus-tardus waveforms between atherosclerotic and non-atherosclerotic RAS,but it still can be applied to the detection of RAS.Furthermore,different cut off values of RI should be established according to the types of RAS. PartⅢDiagnostic value of Tardus—Parvus pattern in the detection of renal artery stenosisObjectiveTo evaluate the diagnostic value of Tardus—Parvus pattern in the detection of different types of renal artery stenosis(RAS).MethodsA study group was composed of 141 patients whose renal arteries were detected by color Doppler flow imaging and were referred to renal arteriography afterwards, including 38 Takayasu arteritis,33 fibromascular dysplasia and 70 atherosclerosis. Doppler spectra of interlobar arteries were obtained,and the acceleration time(AT),the resistive index(RI) and the side-to-side differences of RI(△RI) were recorded.ResultsIn the 280 main renal arteries demonstrated by renal arteriography,there were 31 moderate stenoses(diameter reduction 50%～69%),145 severe stenoses(diameter reduction 70%～99%) and 20 occlusions.Among the 145 stenoses,38 were caused by Takayasu's arteritis,33 by fibromuscular dysplasia and 74 by atherosclerosis.The sensitivity,specificity and accuracy of AT≥0.07s for predicting all severe RAS were 82.58%,94.40%,87.86%,respectively.The best cutoff value of RI(0.50)for predicting severe non- atherosclerotic RAS had a sensitivity of 60.92%,specificity of 90.91%, accuracy of 72.54%.The best cutoff value of RI(0.60) for predicting severe atherosclerotic RAS had a sensitivity of 39.24%,specificity of 89.83%,accuracy of 60.87%.The best cutoff value of△RI was 0.08 with a sensitivity of 64.74%, specificity of 80.65%and accuracy of 68.38%.ConclusionsAT≥0.07s is the best parameter for predicting≥70%RAS,and suitable for the three types of common RAS.The best cutoff value of RI is 0.6 for atherosclerotic RAS,and 0.5 for non-atherosclerotic RAS.The cutoff value of RI should be established according to the types of RAS.The diagnostic efficiency of RI and△RI was not satisfactory,the former might be contributed to the various influencing factors on RI, while the unsatisfactory efficiency of△RI is associated with the high percentage of patients with bilateral RAS.The cutoff of△RI had better to be set at 0.08 for unilateral severe stenosis. PartⅣColor Doppler Sonography in Severe Transplant Renal Artery Stenosis:A Comparison of End-to-End and End-to-Side Arterial AnastomosisObjectiveThe aim of this study was to investigate differences in Doppler parameters between severe transplant renal artery stenosis(TRAS,arterial lumen reduction≥80%) with end-to-end anastomosis and that with end-to-side anastomosis.MethodsWe retrospectively reviewed color Doppler sonography(CDS) and digital subtraction angiography(DSA) images in 38 patients with severe TRAS(19 cases with end-to-end anastomosis and 19 cases with end-to-side anastomosis) between January 1,2000 and December 31,2006.All 38 cases with severe TRAS were initially diagnosed with CDS and confirmed by DSA afterwards.Seven Doppler parameters,including the peak systolic velocity(PSV) in the renal,iliac,anastomosis site and segmental or interlobar artery,Pre-PSV ratio(the ratio of the PSV at the stenotic site to that in the iliac artery), Post-PSV ratio(the ratio of the PSV at the stenotic site to that in the intrarenal arteries, acceleration time in the intrarenal arteries,were measured.ResultsDSA demonstrated all patients with severe arterial stenosis(diameter reduction≥80%). With regard to the location of stenosis.4 stenotic lesions were found in the iliac artery, 20 were at the site of the anastomosis,and the other 14 involved the transplanted renal artery.There were significant differences in PSV in the stenotic artery(P＜0.01),PSV in the iliac artery(P＜0.001) and Pre-PSV ratio(P＜0.001) between TRAS with end-to-end anastomosis and that with end-to-side anastomosis.However,there was no statistically significant difference in AT in the intrarenal artery between the two types of anastomosis(P＞0.05).ConclusionsSignificantly hemodynamic differences between severe TRAS with end-to-end anastomosis and that with end-to-side anastomosis may be the reason for the significantly statistical differences in PSV in the stenotic artery and Pre-PSV ratio.In order to raise the diagnostic accuracy for severe TRAS,PSV in the stenotic artery and Pre-PSV ratio should be established according to the types of arterial anastomoses. However,the same diagnostic cutoff of AT is most suitable for both types of anastomosis.