“小慢波”流速指标对诊断肾动脉狭窄的价值

目的：探讨“小慢波”流速指标对内径减少≥50％的肾动脉狭窄（ RAS）的诊断价值和最佳阈值。方法应用彩色多普勒超声检查出现“小慢波”后并进行肾动脉造影的221例患者（研究组）。测量肾主动脉（ MRA）、段间动脉（ SRA）、叶间动脉（IRA）、弓状动脉（ARA）的收缩期峰值流速（PSV）、舒张末期最低流速（EDV）、阻力指数（RI）、加速时间（AT）及加速度（ AC），统计分析各组参数的差异。肾动脉造影显示动脉内径减少≥50％者定为中-重度RAS。使用ROC曲线（ receive oper-ating characteristic curves ）分析确定最佳诊断指标。计算这些流速指标不同阈值的敏感性、特异性、阳性预测值和阴性预测值。结果肾动脉造影共显示肾动脉狭窄≤50％者16例，50％-99％者197例，完全闭塞2例，无狭窄6例。对于内径减少≥50％的RAS，ROC曲线分析结果显示肾内动脉流速指标具有较好敏感性和特异性，50％-99％的RAS最佳阈值分别为PSV：20 cm/s；EDV：10 cm/s；RI：0.50；AT：0.09 s；AC：1.5 m/s2。结论“小慢波”对于诊断≥50％以上的RAS具有较高的特异性和敏感性，对狭窄度在0-49％敏感性较低，对肾动脉完全闭塞无价值。

Diagnostic value of velocity parameters of Tardus-Parvus for the detection of renal artery stenosis

Objective To evaluate the diagnostic value of velocity parameters of Tardus-Parvus for the detection of renal artery stenosis （ RAS） （ diameter reduction ≥50%） and to determine the useful cutoffs for these parameters .Methods A study group was composed of 221 renal arteries that were detected Tardus-Parvus by color Doppler flow imaging and were referred to abdomino-aorto-re-nal arteriography afterwards .Five Doppler parameters including the peak systolic velocity （ PSV ） , end-diastolic minimum velocity （EDV）, resistance index （RI）, acceleration time （AT）, and accelerated velocity （AC） from each location including renal aorta （ MRA） , segmental artery （ SRA） , interlobar artery （ IRA） , and arcuate artery （ ARA） were archived and compared among the differ-ent groups .Renal artery angiography showed arterial canon reduced 50% or higher RAS .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 the receiver operating characteristic （ ROC） curves.The sensitivity, specificity, and negative and positive predicting values at various cutoffs were calculated .Results Renal artery stenosis degree was less than 50% in 16 cases, 50%-99%in 197 cases, completely occluded in 2 cases, and no stenosis in 6 case by renal arteriography .For RAS with inner diameter re-duction of 50%or more, the ROC curve analysis showed renal artery flow velocity had a good sensitivity and specificity , 50%-99%of the RAS had optimal threshold value in PSV 20 cm/s, EDV 10 cm/s, RI 0.50, AT 0.09 s, and AC 1.5 m/s2.Conclusions Tardus-Parvus had high specificity and sensitivity for diagnosis of stenosis rate in more than 50% of the RAS, low sensitivity for the narrow degree in 0-49%, and no clinical value for the renal artery occlusion .