Renal resistive index in healthy children

OBJECTIVE: The objective of the study was to investigate the relationship between age and renal resistive index (RI) and to determine the normal values and ranges of RI in intrarenal arteries in healthy children. MATERIALS AND METHOD: Color duplex Doppler sonography of interlobar or arcuate arteries was performed in 115 children without clinical or laboratory pathologic changes of the urinary tract. Of these 115 healthy children, 23 were under 12 months of age (group 1), 24 between 12 and 35 months (group 2), 23 between 36 and 71 months (group 3), and 45 between 72 months and 16 years (group 4). Normative data for RI were established for each age group. RESULTS: When age groups were compared, statistically significant differences were observed between age groups 1 and 2 (P=0.007), 1 and 3 (P=0.00), 1 and 4 (P=0.00) and 2 and 4 (P=0.00). No significant differences were observed between age groups 2 and 3 (P=0.452), and 3 and 4 (P=0.078). There was no significant difference between mean RI values of right and left kidney within any age group (P=0.315). CONCLUSION: Results obtained in this study demonstrates that RI is age dependent; it is the highest at birth, from birth declines gradually with increasing age and stabilizes in a certain range (mean RI range regarded as normal for adults) by reaching adult levels.     

Renal masses: characterization with Doppler US.

The vascularity of indeterminate renal masses in 70 patients was investigated prospectively with duplex ultrasound. The peak-systolic Doppler shift frequency obtained from the renal mass was utilized to attempt distinction between benign and malignant lesions. With use of the criterion of a peak-systolic Doppler shift frequency of 2.5 kHz or greater as evidence of neovascularity, 26 of 37 malignant lesions demonstrated tumor signals (70% sensitivity). Thirty-one of 33 benign lesions lacked tumor signals (94% specificity). Both of the false-positive lesions were infections with inflammatory masses, with peak frequencies of 3.0 and 3.7 kHz. Tumor vascularity in most malignant renal mass lesions gives rise to abnormal, high-frequency, Doppler-shifted signals that can aid the differential diagnosis of renal masses.     

Renal transplant pyelocaliectasis: role of duplex Doppler US in evaluation

To distinguish the obstructed from the nonobstructed dilated collecting system of transplanted kidneys without interventional diagnostic measures, the authors prospectively evaluated duplex Doppler analysis (determination of resistive index [RI]) in 35 renal transplant patients with pyelocaliectasis. Proof of the presence or absence of obstruction was obtained at interventional procedures in 18 patients and at clinical follow-up in 17. Thirteen kidneys were obstructed (mean RI, .81 +/- .06), while 22 had nonobstructive dilatation (mean RI, .66 +/- .07). The RI difference was statistically significant (P less than or equal to .01). Of 21 kidneys with a normal RI, only two had obstruction. In both of these, the obstruction was associated with a significant peritransplant collection of fluid due to a ureteral leak. In the seven obstructed transplanted kidneys with follow-up, the mean RI was .82 +/- .06 before nephrostomy and .67 +/- .05 after nephrostomy. Obstruction was a common cause of an elevated RI (greater than or equal to .75). Other causes of transplant dysfunction can be associated with an elevated RI and nonobstructed dilatation. More important, a normal RI should strongly argue against obstruction unless a ureteral leak is also present.     

早期测量搏动和阻力指数:与长期肾移植功能的关系

目的肾移植后1年的早期特定阶段,测定相关搏动指数(PI)和阻力指数(RI)评估肾小球滤过率和死亡截尾移植成活率,用于评价这些多普勒指标的长期预测价值。     

Liver transplant rejection: value of the resistive index in Doppler US of hepatic arteries

The authors prospectively evaluated the accuracy of the resistive index (RI) in Doppler ultrasound (US) for the detection of the increased vascular resistance that theoretically occurs with acute liver transplant rejection. RIs were calculated for the proximal hepatic artery and a more distal hepatic artery branch in 67 liver transplant recipients. Biopsies were performed within 24 hours of transplantation, with no intervening therapy. Examination of biopsy specimens by a single pathologist revealed findings of no, minimal, or moderate to severe rejection. RIs in hepatic arteries showed no significant differences among the three pathologic groups. No correlation was found between the RI and improved or worsened rejection in 11 patients who underwent biopsy and US more than once. RIs in hepatic arteries are of no value in the prediction of liver transplant rejection.     

Renal allograft rejection: evaluation by Doppler US and MR imaging

A prospective study compared the efficacy of Doppler ultrasonography (US) and magnetic resonance (MR) imaging in evaluating 38 renal allografts, with specific attention to transplant rejection. Forty-three Doppler US and 42 MR examinations were performed and interpreted. Histologic correlation was obtained from 22 biopsy or nephrectomy specimens. Clinical correlation or a response to instituted therapy was used as confirmation in the remaining allografts. Accuracy in identifying cyclosporine toxicity or acute tubular necrosis could not be evaluated because there were few such cases, with concomitant rejection in most. The ability to predict and identify presence or absence of rejection was not affected by different serum creatinine values. Doppler US was significantly superior to MR imaging in identifying allograft rejection, demonstrating a higher sensitivity (95% vs. 70%), specificity (95% vs. 73%), and accuracy (95% vs. 71%). Because of its low cost and accessibility, Doppler US should become the primary modality for renal transplant screening.     

Duplex Doppler US in patients with medical renal disease: resistive index vs serum creatinine level.

The relationship between resistive index of arterial Doppler waveform of the native kidney and serum creatinine level has been studied using duplex Doppler sonography in 40 patients with medical renal disease and 28 normal controls. The resistive index of the normal control group and the medical renal disease group was 0.627 +/- 0.042 and 0.823 +/- 0.237, respectively, with statistically significant difference. In the group with medical renal disease, there was a statistically significant correlation between the resistive index and the level of serum creatinine. The study suggests that duplex Doppler sonography may be helpful in evaluation of renal functional status in patients with medical renal disease.