Resistance Index Ratio Research Articles

Fetal aortic to middle cerebral artery resistance index ratio: An indicator of normal and pathologic arterial blood flow distribution

International Journal of Gynecology & ObstetricsVolume 70, Issue S2 p. B60-B60 Free communication Fetal aortic to middle cerebral artery resistance index ratio: An indicator of normal and pathologic arterial blood flow distribution J. Aranyosi, J. AranyosiSearch for more papers by this authorT. Major, T. MajorSearch for more papers by this authorJ. Zatik, J. ZatikSearch for more papers by this authorP. Bettembuk, P. BettembukSearch for more papers by this author J. Aranyosi, J. AranyosiSearch for more papers by this authorT. Major, T. MajorSearch for more papers by this authorJ. Zatik, J. ZatikSearch for more papers by this authorP. Bettembuk, P. BettembukSearch for more papers by this author First published: 10 December 2003 https://doi.org/10.1016/S0020-7292(00)86308-0AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume70, IssueS22000Pages B60-B60 RelatedInformation

Utility of the resistance index ratio in differentiating obstructive from nonobstructive hydronephrosis in children

Utility of the resistance index ratio in differentiating obstructive from nonobstructive hydronephrosis in children

Assessment of fetal and placental blood flow in primates using contrast enhanced ultrasonography.

Ultrasonographic contrast agents that stay within the vascular space and do not cross the placenta may permit differentiation between the maternal and fetal portions of the placenta and may be clinically useful for diagnosis of placental abnormalities. This study was performed to assess the effects of Levovist (Schering AG, Berlin) on the placental circulation and to determine whether hemodynamic effects on the fetus occur. Ten studies were performed in five pregnant macaques (median weight, 9.15 kg; range, 6.15 to 11 kg; median gestational age, 121 days; range, 34 days to term) under anesthesia. Gray scale, color, and duplex Doppler sonographic scans of the fetus and placenta were acquired using a 5 MHz curved array transducer. Fetal heart rate, resistive index, and systolic-diastolic ratios were measured in the fetal middle cerebral artery, aorta, umbilical artery, and uterine artery before and after administration of contrast agent. The following dose regimen was tested: 5 ml of physiologic saline solution followed by 0.1 ml/kg of 300 mg/ml Levovist (diagnostic dose), 0.5 ml/kg of 400 mg/ml Levovist (maximum dose), and 5 ml physiologic saline solution. The order of diagnostic dose and maximal dose was randomized among animals. Color enhancement of the basal portions of the placenta was documented after administration of contrast agent. Heart rate and middle cerebral artery systolic-diastolic ratio did not change between baseline and injections. A 7% decrease of the resistive index from baseline to maximum dose was measured in the uterine artery (not significant). A 7.7% decrease in the systolic-diastolic ratio from baseline to maximum dose was recorded in the umbilical artery. However, an identical change was measured after saline solution was injected. The resistive index in the aorta increased by 2.6% from baseline to maximum dose, a change that was not significant (P > 0.5). Ultrasonographic contrast enhancement of the maternal circulation in placenta is demonstrated to be without significant effects on the fetal circulation as measured in this limited population.

The Ultrasonographic Differentiation of Obstructive Versus Nonobstructive Hydronephrosis in Children: A Multivariate Scoring System

Purpose We identified sonographic prognosticators to aid in distinguishing obstructive from nonobstructive hydronephrosis in children. Materials and Methods Twelve sonographic variables were initially analyzed to determine significant associations between the variables and the presence of urinary tract obstruction as defined by diuretic radionuclide renography. The significant findings were subsequently subjected to logistic regression models to identify potential predictors for obstructive hydronephrosis. Results The 7 variables associated with a significantly higher risk of urinary tract obstruction were increased echogenicity, parenchymal rims 5 mm. or less, contralateral hypertrophy, resistive index ratio 1.10 or greater, resistive index difference with diuresis of 70% or greater, ureter diameter 10 mm. or greater and aperistaltic ureter. These variables were used for the development of a multivariate scoring system. Conclusions The obstructive scoring system shows promise as a screening method for the sonographic differentiation of obstructive from nonobstructive hydronephrosis in children.

Sonographic estimation of umbilical coiling index and correlation with doppler flow characteristics

To quantitate umbilical vascular coiling antenatally, and to correlate the coiling index with Doppler flow characteristics in umbilical vessels. We studied 45 normal term fetuses within 24 hours before delivery. The umbilical coiling index was calculated using sonographic longitudinal views of cord vessels from several segments antenatally, and by dividing the total number of helices by the cord length (in centimeters) postnatally. Doppler flow velocities were obtained from umbilical arteries and vein in each cord. Flow characteristics were correlated with the umbilical coiling index. The mean (+/- standard deviation) umbilical coiling index was 0.44 +/- 0.11 in the antepartum period and 0.28 +/- 0.08 after birth. Regression analysis showed a significant linear trend (r = 0.71, P < .001). The correlations between sonographic coiling index and umbilical arterial Doppler flow characteristics (mean velocity, pulsatility index, resistance index, and systolic-diastolic ratio) were not significant. The sonographic coiling index was related to time-averaged velocity and flow in the umbilical vein. A good correlation was found between umbilical vein flow and the coiling index, with a significant linear trend (r = 0.59, P < .001). An intrauterine umbilical coiling index can be determined by ultrasound and correlates well with the actual index at birth. The sonographic umbilical coiling index is related to Doppler flow characteristics in the umbilical vein.

The Renal Vascular Response to Acutely Elevated Intrapelvic Pressure: Resistive Index Measurements in Experimental Urinary Obstruction

Purpose To assess the accuracy of resistive index (RI) in the diagnosis of obstruction. Materials and Methods The time course of RI and its relationship to intrapelvic pressure were measured in 6 dogs following unilateral obstruction. Results Changes in RI 1) occurred as early as 1/2 hour after acute obstruction, 2) only reached diagnostic sensitivity after 3 to 4 hours, 3) accurately diagnosed obstruction whenever the RI ratio between the kidneys exceeded 1.15 and 4) were uninfluenced by alterations in intrapelvic pressure. Conclusions Because RI more closely reflects changes in renal blood flow than pelvic pressure, it can accurately diagnose acute obstruction but only after several hours. Diagnostic accuracy in chronic obstruction may be influenced by these physiologic relationships.

Accuracy of the Middle-Cerebral-To-UmbilicalArtery Resistance Index Ratio in the Prediction of Neonatal Outcome in Patients at High Risk for Fetal and Neonatal Complications

Accuracy of the Middle-Cerebral-To-UmbilicalArtery Resistance Index Ratio in the Prediction of Neonatal Outcome in Patients at High Risk for Fetal and Neonatal Complications

Fetus-Placenta-Newborn: Accuracy of the middle-cerebral-to-umbilical-artery resistance index ratio in the prediction of neonatal outcome in patients at high risk for fetal and neonatal complications

The purpose of this study was to determine the accuracy of the middle-cerebral-to-umbilical-artery resistance index ratio in the prediction of fetal outcome in pregnancies at high risk for fetal and neonatal morbidity and mortality. A prospective controlled nonrandomized study was conducted in the high-risk pregnancy unit of a teaching hospital. The control group was formed by 20 healthy women with uncomplicated singleton pregnancies and healthy children delivered at term. The study group consisted of 115 women referred to the high-risk pregnancy unit because of a variety of pregnancy complications. Longitudinal evaluation of the control group and cross-sectional evaluation of the study group were carried out at different gestational ages by means of duplex Doppler ultrasonography. The main outcome measures were fetal growth retardation, preterm birth, and neonatal morbidity. The middle-cerebral-to-umbilical-artery ratio remains relatively constant (mean +/- SD 1.33 +/- 0.19) between 27 and 37 weeks. A cutoff value of 1.0 (sensitivity 57.9%, specificity 75.6%, false-positive rate 24.4%) was selected from the receiver-operator characteristic curve analysis. This cutoff value successfully identified a population at significant risk of fetal growth retardation (relative risk 3.07, 95% confidence interval 1.73 to 5.45, exact two-tailed p = 0.0009) and severe neonatal morbidity (Mann-Whitney U = 463.5, two-tailed p = 0.03). The middle-cerebral-to-umbilical-artery ratio was not useful in the prediction of preterm birth. A middle-cerebral-to-umbilical-artery ratio of < or = 1.0 identifies a subgroup of patients at high risk for fetal growth retardation and severe neonatal morbidity.

Distribution and variability of resistiveindex values in undilated kidneys in children

Objectives. To assess better the utility of duplex Doppler sonography in the diagnosis of obstructive hydronephrosis in children, we specifically studied undilated urinary tracts with the intention of establishing a nomogram of resistive index (RI) values and determining if the RI value of 0.7 reliably precludes an undilated collecting system. Methods. Renal duplex Doppler ultrasound was performed in a standard fashion on 47 children more than 12 months of age (93 renal units) where there was no suspicion of upper urinary tract dilation. RI and RI ratio (RIR) were calculated and statistical analysis performed. Results. There were 27 males and 20 females 12 to 180 months old (mean, 63.9 months). Kidney size ranged from 5.0 to 9.8 cm (mean, 7.28 cm), RI ranged from 0.34 to 0.94 (mean, 0.65), and RIR ranged from 1.00 to 1.76 (mean, 1.14). There was no statistically significant relationship between the RI and renal size or laterality, gender, or age (p > 0.05). However, between the ages of 24 and 108 months, the RI was significantly higher in females compared with males (p = 0.002). If one were to use 0.7 and 1.10 as discriminatory values for RI, 37% of renal units had values above 0.7, and 41 % of RIR values were above 1.10. Conclusions. We believe that RI values in undilated kidneys of children vary significantly and its routine use and reliability need to be evaluated further in the pediatric population.

Intrarenal doppler findings of upstream renal artery stenosis: A preliminary report

To diagnose 60% or greater diameter-reducing stenosis of the renal artery (RAS), color Doppler imaging (CDI) and angiography were performed on 44 hypertensive and 16 normotensive cases. In this prospective, double-blind study we evaluated the related intrarenal waveform changes. In both the right and left kidneys of normotensive cases, at the level of interlobar arteries, the results indicated a symmetric finding in peak systolic/ end diastolic velocities (S/D), pulsatility index (PI) and resistive index (RI) ratios. The results in the stenotic kidneys among the hypertensive group indicated that index values were significantly lower in the stenotic kidneys than those of the contralateral kidneys, the kidneys of control and nonstenotic hypertensive cases. To quantify this observation we suggest “perfusion indexes,” which require more studies on a greater number of hypertensive cases. It was concluded that measuring the index values of intrarenal arterial waveforms is easier and more accessible in diagnosing RAS than obtaining those of the main renal artery.

Maternal hyperoxygenation: a fetal blood flow velocity prognosis test in small-for-gestational-age fetuses?

Maternal hyperoxygenation tests were performed in 20 small-for-gestational age fetuses using 8 l/min of 70% humidified oxygen given for 20 min through a face mask. Assessments were made of the fetal blood flow velocity, and the placental resistance index, cerebral resistance index and cerebroplacental ratio were calculated in 78 normal pregnancies and in the 20 small-for-gestational-age fetuses during the hyperoxygenation test. The test was positive when the velocity indices increased by more than 10%. The reference ranges for placental and cerebral resistance indices were derived from the data measured in the 78 normal pregnancies. Of the 20 small-for-gestational-age fetuses, three had a normal placental resistance index with a negative oxygen test response and a good fetal outcome. Seven had a mild increase in placental resistance index (> +2SD) and a brain-sparing effect was observed (cerebral resistance index < -2SD or cerebroplacental ratio < l). In these seven fetuses, the fetal outcome was not poor, whether the oxygen test response was negative or positive. Ten of the 20 small-for-gestational-age fetuses had no umbilical diastolic flow (placental resistance index = 1) and a brain-sparing effect. Their outcome was strongly dependent on the oxygen test response: a positive response indicated a good prognosis, a negative one a poor fetal outcome.