Platt J F, Rubin J M, Ellis J H
Department of Radiology, University of Michigan Hospitals, Ann Arbor 48109-0030.
AJR Am J Roentgenol. 1989 Nov;153(5):997-1000. doi: 10.2214/ajr.153.5.997.
Because animal studies have shown that renal obstruction increases renal vascular resistance, we theorized that obstruction would change the Doppler waveform. We studied the value of the resistive index (RI) calculated from the duplex Doppler waveform to distinguish between obstructive and nonobstructive pyelocaliectasis in 229 kidneys in 133 patients. The RI is the peak systolic frequency shift minus the minimum diastolic frequency shift, then divided by the peak systolic frequency shift. Duplex Doppler sonography was performed prospectively in 70 kidneys with pyelocaliectasis before the presence or absence of obstruction was established. In 54 of 70 kidneys, the presence or absence of obstruction was proved by interventional methods (percutaneous nephrostomy, antegrade or retrograde pyelography, loopography), and in the rest it was proved by body CT, excretory urography, or surgery. Thirty-eight kidneys were found to be obstructed, and 32 had nonobstructive dilatation. In addition, 159 kidneys without pyelocaliectasis were studied to identify possible limitations of Doppler sonography in the diagnosis of obstruction. Clinical history and laboratory data were used to determine that 109 of these kidneys were in normal subjects and 50 were in patients with nondilated renal disease. There was a significant difference between the mean RI of the obstructed (0.77 +/- 0.05) and the nonobstructed dilated (0.63 +/- 0.06) kidneys (p less than .01). Analysis of the receiver-operating-characteristic curve showed an RI of 0.70 to be a good discriminatory level for obstruction, resulting in a sensitivity of 92%, a specificity of 88%, and an accuracy of 90%. All 109 normal kidneys had an RI less than 0.70. Over half (27/50) of the kidneys in patients with nondilated renal disease had an elevated RI (greater than or equal to 0.70). Ninety-six patients had Doppler examinations on both kidneys, and in only six patients did the RI values of each kidney differ by more than 0.10; all six were proved to have unilateral obstruction. Use of duplex Doppler sonography should improve the specificity, and thus the accuracy, of sonography in the noninvasive diagnosis of obstruction and should be used when a dilated collecting system is identified.
由于动物研究表明肾梗阻会增加肾血管阻力，我们推测梗阻会改变多普勒波形。我们研究了从双功多普勒波形计算得出的阻力指数（RI）在鉴别133例患者229个肾脏的梗阻性和非梗阻性肾盂积水方面的价值。RI是收缩期峰值频移减去舒张期最小频移，再除以收缩期峰值频移。在确定70个存在肾盂积水的肾脏有无梗阻之前，前瞻性地进行了双功多普勒超声检查。70个肾脏中的54个，其有无梗阻通过介入方法（经皮肾造瘘术、顺行或逆行肾盂造影、肾盂造影）得以证实，其余的则通过身体CT、排泄性尿路造影或手术证实。发现38个肾脏存在梗阻，32个有非梗阻性扩张。此外，对159个无肾盂积水的肾脏进行了研究，以确定多普勒超声在梗阻诊断中的可能局限性。利用临床病史和实验室数据确定其中109个肾脏来自正常受试者，50个来自无肾扩张疾病的患者。梗阻性肾脏（0.77±0.05）和非梗阻性扩张肾脏（0.63±0.06）的平均RI之间存在显著差异（p＜0.01）。对受试者工作特征曲线的分析表明，RI为0.70是梗阻的良好鉴别水平，敏感性为92%，特异性为88%，准确性为90%。所有109个正常肾脏的RI均小于0.70。无肾扩张疾病患者的肾脏中，超过一半（27/50）的RI升高（大于或等于0.70）。96例患者对双侧肾脏进行了多普勒检查，只有6例患者两侧肾脏的RI值差异超过0.10；所有6例均被证实有单侧梗阻。双功多普勒超声的应用应能提高超声在梗阻无创诊断中的特异性，从而提高准确性，并且在发现集合系统扩张时应予以使用。
