Resistive index

We studied the role of duplex Doppler ultrasonography in the diagnosis of renal obstruction caused by ureteral calculi. Using duplex Doppler sonography, we evaluated the intrarenal hemodynamics of 27 patients who presented to the emergency department with renal colic. We performed Doppler ultrasonography on patients in whom US did not reveal any pathology causing renal colic and calculated and compared mean RI values of normal and obstructed kidneys and ΔRI values of each group. Threshold levels for the diagnosis of urinary tract obstruction (mean RI ≥ 0.70 and ΔRI ≥ 0.08) were used to determine the sensitivity and specificity of Doppler sonography for the diagnosis of urinary tract obstruction. Patients were investigated for revealing calculi diagnosis either by stone excretion history, intravenous pyelography or non contrast enhanced urinary computed tomography. A total of 162 intrarenal arterial Doppler recordings were made on 54 kidneys. Of the 16 patients with urinary obstruction, 11 (68%) had sonographic evidence of pelvicalyceal dilatation. The mean RI of the 16 obstructed and 11 unobstructed kidneys was 0.69 ± 0.04 and 0.61 ± 0.06 (mean ± standard deviation), respectively. The difference between the mean RI values for each group was statistically significant (P P P 

Background The arterial vascularity of the hip has been investigated in normal infants using duplex Doppler sonography. This study addressed the differences in hip vascularity in infants with respect to gender and acetabular morphology. Objective To determine whether there is a relationship between the resistive index of the vessels of the femoral chondroepiphysis and the alpha angle in normal infant hips and in those with developmental dysplasia of the hip. Materials and methods We studied 76 hips (38 patients) with gray-scale and power Doppler US. The patients were referred because of a possible abnormal clinical hip examination or had risk factors for developmental dysplasia of the hip. The infants ranged in age from 1 day to 6 weeks. There were 13 boys and 25 girls. Gray-scale images were initially performed in the coronal and transverse planes to evaluate acetabular morphology, alpha angle and position of the femoral chondroepiphysis relative to the acetabulum. The hips were then examined with power Doppler US, in both sagittal and transverse planes, to identify arterial vessels within the femoral epiphysis. Resistive indices were then recorded from the spectral analysis in each vessel identified. Each examination was performed by one of five pediatric radiologists. Mixed model regression was used to assess the relationship between resistive index and alpha angle, age and gender. Results Of the 76 hips, 34 had an alpha angle of 60° or greater and were classified as normal, 26 had an alpha angle between 50° and 59° and were classified as immature, and 13 had an alpha angle of less than 50° and were either subluxed or dislocated at the time of examination. At least two vessels were documented in each femoral epiphysis except in three hips, in which no vessels could be documented because of technical factors. There was a statistically significant linear relationship between the alpha angle and resistive index, such that the resistive index tended to rise with increasing alpha angle (P=0.0022). In addition, female infants had a significantly higher average resistive index than the average resistive index in male infants with the same alpha angle (P=0.0005). Conclusion There is a direct linear relationship between alpha angle and resistive index in the infant hip. Female infants have a higher average resistive index than male infants. We believe that these results might serve as a model for predicting an infant hip at risk of ischemia. In addition, the fact that lower resistive indices of the femoral epiphysis are associated with acetabular dysplasia might help explain the documented low incidence of avascular necrosis in untreated hip dysplasia.

Coke in the blast furnace experiences great changes in their properties during the blast furnace operation. Pulverized Coal Injection (PCI) into the blast furnace through tuyeres together with oxygen enrichment affect coke properties and blast furnace operation. Using coke sampler at tuyere level, coke samples were collected and analysed at various coal injection rates in the both conventional and co-axial oxygen enrichment. With the help of information obtained from coke sampling experiments, gas permeability resistance index at lower part of blast furnace (LK) and mean size variation of coke were predicted and matched well with the measurements.

Doppler ultrasound is an emerging technology that has the potential to increase the diagnostic, monitoring, and predictive capabilities of equine theriogenologists and researchers. The technology is based on Doppler-shift frequencies, wherein the ultrasound frequency of echoes from moving red cells is increased or decreased as the cells move toward or away from the transducer. In spectral mode, the blood flow in a specific vessel can be assessed by placing a sample-gate cursor on the image of the lumen of the vessel. In addition, an angle cursor can be used to represent the angle of intersection of the ultrasound beams with the direction of blood flow (Doppler angle). The Doppler-shift frequency and the Doppler angle are used by the instrument for computing blood velocity. The focused results from placement of a sample gate in an artery are displayed by a spectrum that represents the changing velocities over time in association with the pulses of cardiac cycles. Peak systolic, end diastolic, and time-averaged maximum velocities are computed and shown for a selected cardiac cycle. Doppler indices (resistance index, RI; pulsatility index, PI) are ratios that are computed from various points on the spectrum. The indices are relatable to the hemodynamics of the tissue supplied by the artery. Increasing RI or PI values indicate increasing resistance and decreasing perfusion of the distal tissues. In color-flow mode, Doppler-shift frequencies are obtained from areas delineated by the operator on the B-mode image and are transformed and expressed as color-coded spots representing areas of blood flow. Vascular perfusion of a structure can be quantitated by the number of colored pixels in an image or can be estimated subjectively by the extent of the colored spots. The Doppler technology has the potential for providing information on the status and future success of a structure. However, realization of the expected potential will depend on future experience and research.

Purpose: The aim of this study is represented by the assessment of the intrarenal vascularization, using color Doppler ultrasonography of the interlobar renal arteries.
Material and methods: The study was performed on two groups of pregnant women: group A, formed by 10 healthy pregnant women, and group B, formed by 10 pregnant women with preeclampsia. Assessment of the intrarenal vascularization was done by color Doppler ultrasonography of the interlobar renal arteries, using ALOKA 4000 SSD with 3.5 MHz convex transducer. Resistive index (RI), pulsatility index (PI), and acceleration time (AT) were determined in all cases. All data were expressed as mean ± standard deviation. Statistical analysis was done using Student’s t-test, p<0.05 was considered to be statistically significant.
Results: The mean age of patients was 32.15±3.41 years (group A), respective 34.02±5.01 years (group B), and the gestational age was 27.7±2.8 weeks (group A), respective 26.9±1.7 weeks (group B). The values of RI were 0.64±0.03 (group A), 0.65±0.02 (group B) (p>0.05). The values of PI were 1.13±0.06 (group A), 1.11±0.04 (group B) (p>0.05). The values of AT were 70.1±8.78 msec. (group A), 122.2±24.58 msec. (group B) (p<0.001).
Conclusion: In pregnant women with preeclampsia, resistive index and pulsatility index have normal values, but acceleration time is prolonged, due to arterial renal vasoconstriction.

Purpose To assess ocular hemodynamic response to intravitreal triamcinolone in patients with macular edema due to diabetes or retinal vein occlusion. Methods Forty-three patients that were injected by intravitreal triamcinolone acetonide (0.1 cc 4 mg) for unilateral macular edema due to diabetes mellitus (n = 17) and occlusion of retinal vein (n = 26) underwent ocular hemodynamic evaluation by color Doppler imaging (CDI) before and one, two and three months after injection. Non-injected fellow eyes as well as 16 healthy volunteers were also evaluated. Results In patients with diabetic macular edema, there was no hemodynamic difference between eyes to be injected and non-injected at baseline (P > 0.23). Compared to controls, a significant difference existed in the ophthalmic artery resistant index (P = 0.001) and end-diastolic velocity (P < 0.001) in diabetics. At one month, compared to fellow eyes, change in end diastolic velocity from baseline in treated eyes was significantly decreased in posterior ciliary arteries (0.68 ± 0.34 cm/s [mean ± SEM] vs. −1.04 ± 0.81 cm/s, P = 0.012). Throughout the study period, no significant alteration from baseline in the resistant index of any artery was noted in treated diabetic eyes (P > 0.05). In eyes with retinal vein occlusion, baseline CDI evaluation demonstrated reduced posterior ciliary arteries systolic flow velocity compared to fellow and control eyes (13.24 ± 1.04 cm/s, 16.37 ± 0.76 cm/s and 14.33 ± 1.41 cm/s, respectively, P = 0.007). Increased peak systolic velocity in the posterior ciliary arteries at one week (P = 0.02), one month (P = 0.005) and two months (P  = 0.04), and increase in central retinal artery resistant index at one month was noted (P = 0.05). Conclusion Intravitreal triamcinolone temporarily changed central retinal artery blood flow and posterior ciliary arteries' peak systolic blood velocity in eyes with retinal vein occlusion whilst no response of blood flow to triamcinolone injection but only transiently altered end diastolic blood velocity in posterior ciliary arteries was observed in diabetic eyes.

The legume pod borer, Helicoverpa armigera (Hübn.), is one of the major constraints to chickpea production, and host plant resistance is an important component for the management of this pest. The levels of resistance in the cultivated chickpea are low to moderate, and therefore, we evaluated 17 accessions of perennial Cicer along with three cultivated chickpea genotypes for resistance to H. armigera. There was a significant reduction in both leaf feeding and larval weights when the larvae were fed on the leaves of Cicer microphyllum Benth. accessions ICC 17146, ICC 17236, ICC 17240, and ICC 17248. Relative resistance index based on leaf feeding, larval survival, and larval weight indicated that C. microphyllum accessions ICC 17146, ICC 17236, ICC 17234, ICC 17240, ICC 17243, and ICC 17248 were highly resistant to H. armigera. Under natural infestation, accessions belonging to C. microphyllum, C. canariense Santos Guerra et Lewis, and C. macracanthum M. Pop suffered a damage rating of <2.0 compared to 4.0 in C. judaicum Boiss. accession ICC 17148 (annual species) and 8.5–9.0 in the cultivated chickpeas (1 = <10% leaf area damaged, and, 9 = >80% leaf area damaged). There was considerable diversity in the accessions belonging to perennial wild species of chickpea, and these can be exploited to increase the levels and diversify the basis of resistance to H. armigera in the cultivated chickpea.

Increased circadian variability of airway caliber is a key feature of asthmatic patients, but it has not been addressed in animal models of asthma. Furthermore, animal studies on circadian rhythmicity of airway resistance are very scanty. We used a plethysmographic method for unrestrained guinea pigs to monitor a lung resistance index (iRL) during 24 h. We found circadian variability of iRL values, which were fitted by a sinusoidal curve. Acrophase and bathyphase, characterizing the timing of narrowest and widest airway caliber, respectively, were found at 02:03, and 15:34 h. iRL values at these time-points were statistically different (P<10−5). Moreover, average resistance during the dark period was significantly higher (P<0.0001) than during the light period. Immediately after an acute ozone exposure (3 ppm for 1 h) an increase in iRL was demonstrated (P<0.01), which lasted for 2 h, and tended to remain high for the next hour. After guinea pigs recovered from this obstruction, the circadian rhythm and variability of airway caliber were unaffected. Our results show that a circadian rhythm of iRL takes place in guinea pigs, greatly resembling what occurs in humans, and that ozone exposure causes a transient airway obstruction, but fails to reproduce the increased variability of airway caliber observed in asthmatic patients.

To assess the contribution of a second injection of vasoactive medication into the corpus cavernosum during the duplex Doppler study for evaluation of young patients with vasculogenic erectile dysfunction (ED). Thirty-five patients, 23 to 50 years old (median age 43), clinically diagnosed as having veno-occlusive ED underwent a color duplex Doppler study. The peak systolic velocity, end-diastolic velocity, resistance index, and arterial diameter measurements were obtained from both cavernosal arteries before and 2, 5, 10, and 20 minutes after an intracavernous injection of a vasoactive drug. All patients were reinjected with similar doses of the same medication, and all measurements were repeated. The erection quality was estimated 20 minutes after each injection. The peak systolic velocity after the second injection was significantly higher statistically than after the first injection (P &lt;0.02). No differences in end-diastolic velocity, resistance index, arterial diameter, or th...

The objectives of this study were to evaluate the usefulness of the middle cerebral artery to umbilical artery resistance index ratio (C/U ratio) as a predictor of adverse perinatal outcome, and to show that the absence of fetal umbilical artery end-diastolic velocity (AEDV) in SGA fetuses is associated with high morbidity and mortality. In this prospective study, color Doppler flow imaging was used for the estimation of the C/U ratio in fetuses that were small for their gestational age, in 70 singleton pregnancies between 29 and 42 weeks of gestation. The subjects were categorized into two groups, with Group A consisting of 35 small for gestational age (SGA) fetuses with a normal C/U ratio (1.05 or higher), and Group B comprising 35 SGA fetuses with an abnormal C/U ratio (below 1.05). The mean C/U ratio values for birth weight and gestational age were higher in group A than in group B. Fetuses born to mothers in group B stayed longer in the neonatal special care unit (NSCU), whereas the period from ultrasound examination to delivery was higher in the cases in group A. A higher percentage of mothers with an abnormal C/U ratio underwent cesarean section. Fetuses with an absent end-diastolic velocity of the umbilical artery had a higher morbidity. Three stillbirths occurred in fetuses with an absent end-diastolic velocity of the umbilical artery. Our results suggest that the C/U ratio is a good predictor of neonatal outcome, and could be used to identify fetuses at risk of morbidity and mortality. Fetal umbilical artery AEDV with intrauterine growth restriction is associated with high perinatal morbidity and mortality.

To study the outcomes of patients with compensated hepatitis C virus-related cirrhosis. Twenty-four grade A5 and 11 grade A6 of Child-Pugh classification cirrhotic patients with active virus replication, treated for a mean period of 31.3 +/- 5.1 mo with moderate doses of interferon-alpha and ribavirin, were compared to a cohort of 36 patients with similar characteristics, without antiviral treatment. Salivary caffeine concentration, a liver test of microsomal function, was determined at the starting and thrice in course of therapy after a mean period of 11 +/- 1.6 mo, meanwhile the resistive index of splenic artery at ultra sound Doppler, an indirect index of portal hypertension, was only measured at the beginning and the end of study. Eight out of the 24 A5- (33.3%) and 5 out of the 11 A6- (45.45%) treated-cirrhotic patients showed a significant improvement in the total overnight salivary caffeine assessment. A reduction up to 20% of the resistive index of splenic artery was obtain...

Indirect measurement of renal vascular resistance by duplex Doppler waveform analysis was evaluated in relation to aging and some pathophysiological conditions. Baseline renal resistive index (RRI) (peak systolic frequency shift - lowest diastolic frequency shift/peak systolic frequency shift) was measured in healthy controls aged 20 to 85 years by analyzing the blood flow velocity waveform of interlobar arteries. RRI changes induced by sympathetic activation (cold pressor test and handgrip test) or by fluid load were evaluated. Both repeatability and reproducibility were very good, as the intra and interoperator variations were all less than their reproducibility coefficients. RRI showed a significant increase with aging (ANOVA P &lt; .001), particularly evident in subjects older than 50 years. Both the cold pressor test and handgrip test induced in all the subjects (n = 16) a significant increase in RRI (P &lt; .001), from 0.59 +/- 0.04 to 0.69 +/- 0.04 (12 +/- 6%) for the cold pr...

Aim of our study was to evaluate Doppler renal blood flow velocity in asphyxiated neonates and to correlate renal function to Doppler findings. Doppler renal blood flow velocity was evaluated in 23 severely asphyxiated neonates born at a gestational age >32 weeks and compared to our standard Doppler data obtained in 25 healthy neonates comparable for gestational age and birth weight. Renal Doppler ultrasound was performed on the 1st and 3rd days of life. Renal function was investigated in the first 2 weeks of life. Asphyxiated neonates showed mean values of systolic velocity and mean velocity significantly reduced (PP Conclusion Our findings indicate that decreased Doppler renal flow systolic velocity observed in asphyxiated neonates on the 1st day of life is a useful predictive index for subsequent development of acute renal failure, with 100% sensitivity and 63.6% specificity.