RENAL RESISTIVE INDEXES - VARIABILITY IN DOPPLER US MEASUREMENT IN A HEALTHY POPULATION

PURPOSE: To determine the variability in resistive index (RI) in norma l kidneys, possible causes of variability, and consequences of reporti ng a single value. MATERIALS AND METHODS: Doppler ultrasound RI measur ements were obtained in the upper, middle, and lower regions of 118 ki dneys in 58 healthy subjects (aged 24-70 years; 35 women, 23 men) who subsequently underwent angiography. The effects of sampling a particul ar parenchymal region, vascular territory, or kidney were assessed. RE SULTS: Kidney region, vascular territory, and right Versus left kidney had no consistently significant effect (P less than or equal to.05) o n RI. Age had a statistically significant effect. RI readings were hig hly correlated with each other both within a subject and within a kidn ey. The probability that a single RI value would exceed 0.70 in a heal thy 45-year-old subject was 6%; this decreased to 3% when three readin gs were averaged. CONCLUSION: The variability of RI measurements in a kidney suggests that a number of RI readings should be averaged before a single representative value is reported.