Duplex scan and histologic assessment of acute renal injury in a kidney-kidney crosstalk swine experimental model (original) (raw)
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Haemodynamics imaging of swine segmental kidney artery using duplex Doppler technique
Journal of Veterinary Research
Introduction: The aim of the study was to assess the usefulness of duplex Doppler to objectify swine renal arterial flow in physiological conditions. The pig kidney was selected for its morphological similarities to the human and for the results therefore offering data to wider research. Material and Methods: Six White Large x Landrace sows, of 48.5–53 kg b.w. were used. Vascular flow parameters were acquired with a convex probe USG device with a duplex Doppler function using pulsed waves (frequency range of 5–7.5 MHz). Segmental kidney arterial flow was measured. Results: The RI values were within the 0.57 (min) to 0.6 (max) range, ̄xRI was 0.58 (±0.014), and the SD2 value was 0.0002. The PI index values ranged from 1.21 (min) to 1.3 (max), and ̄xRI was 1.24 (±0.035). The value of SD2 was 0.00123. In the S/D index, the results fell between 2.2 (min) and 2.49 (max), with ̄xS/D of 2.29 (±0.117). The value of variance SD2 was 0.0139. A double analysis of correlation between indices sh...
Noninvasive diagnosis of renal artery stenosis by ultrasonic duplex scanning
Journal of Vascular Surgery, 1986
We retrospectively studied the resuks of duplex scanning for evaluation of renal artery disease in 158 patients. Satisfactory examinations were achieved in 144 patients (90%). Arteriograms were available for 43 renal arteries. We used the ratio of the peak velocities in the renal artery and the aorta (RAR) to separate nonstenotic arteries (less than 60% diameter reduction) from stenotic arteries (greater than 60% diameter reduction). With an RAR of greater than 3.5 to indicate stenotic lesions, duplex scanning had a sensitivity of 91% (20 of 22 diseased arteries correctly identified) and specificity of 95% (20 of 21 normal or insignificantly diseased arteries correctly identified). One of four occluded arteries was incorrectly interpreted as patent because of misidentification of a collateral vessel. Prospective studies will be necessary to validate this test and establish other criteria for a more detailed classification of renal artery stenosis. The ratio of the end-diastolic to peak systolic velocities in the renal artery (EDR) tended to decrease with increasing serum creatinine levels, presumably because renal vascular resistance increases with endstage parenchymal disease. EDR may prove useful in the detection of advanced parenchymal disease before renal artery revascularization is attempted. (J VASC SURG 1986; 4:450-6.) Volume
Renal atrophy and arterial stenosis. A prospective study with duplex ultrasound
Hypertension, 1994
Renal artery disease is an important cause of both renal failure and hypertension. Duplex ultrasound is a reliable noninvasive method for classifying the severity of renal artery lesions and can be repeated to follow the course of the disease over time. The purpose of this study was to determine the changes in kidney size associated with various degrees of renal artery disease. Serial kidney lengths were measured as part of a prospective duplex ultrasound study of patients with renal artery narrowing. Fifty-four patients (22 men, 32 women; mean age, 65.8 years) with 101 renal artery and kidney sides eligible for follow-up were evaluated at 6-month intervals for an average of 14.4 months (range, 4 to 24 months). No kidneys with renal arteries classified as normal or less than 60% diameter stenosis by duplex criteria were found to have a decrease in
In vivo swine kidney viscoelasticity during acute gradual decrease in renal blood flow: pilot study
Revista de ingenieria biomedica, 2013
Elasticity imaging methods have been used to study kidney mechanical properties and have demonstrated that the kidney elastic modulus increases with disease state. However, studies in swine suggests that kidney elastic modulus is also affected by hemodynamic variables. A newly emerging method called Shearwave Dispersion Ultrasound Vibrometry (SDUV) offers a tool to determine renal elasticity and viscosity in vivo. The purpose of this study is directed toward evaluating the feasibility of SDUV for in vivo measurements of healthy swine kidney during acute gradual decease of renal blood flow. In this study in vivo SDUV measurements were made on a group of 5 normal swine kidneys at baseline renal blood flow (RBF) and 25, 50, 75 and 100% decrease in RBF. The shear elastic modulus at full baseline was 7.04 ± 0.92 kPa and 3.48 ± 0.20 kPa at 100% decrease in RBF. The viscosity did not change between baseline (2.23 ± 0.33 Pa·s) and 100% decrease in RBF (2.03 ± 0.32 Pa·s). The data from this ...
Renal duplex sonography: Main renal artery versus hilar analysis
Journal of Vascular Surgery, 2000
The purpose of this study was to compare the accuracy of main renal artery Doppler scanning interrogation and hilar analysis to diagnose hemodynamically significant renal artery disease. Methods: From January 1998 to August 1999, 41 patients had renal duplex sonography with both main renal artery interrogation and hilar analysis followed by angiography. They form the basis of this review. The sample consisted of 24 men and 17 women, with a mean age of 68.9 ± 10.2 years, who provided 80 kidneys for comparative analysis. Significant renal artery disease revealed through angiography was defined as ≥ 60% diameter-reducing stenosis or occlusion. Peak systolic velocity (PSV) (in meters per second) and the presence of poststenotic turbulence (PST) were determined from main renal artery interrogation. Acceleration time (AT) (in milliseconds) was measured by means of hilar analysis. Significant renal artery stenosis was defined by a PSV of 2.0 m/s or more and a PST or an AT more than 100 ms. Sensitivity analyses of both PSV and AT were examined, and 95% CIs were computed. Receiver operating characteristic curves were used to estimate optimal values for PSV and AT. Results: Angiography revealed hemodynamically significant fibromuscular dysplasia in 5 kidneys (4 patients), atherosclerotic stenosis ≥ 60% in 48 kidneys (30 patients), and renal artery occlusion in 4 kidneys (4 patients). Kidneys with significant renal artery stenosis had a higher PSV (2.54 ± 0.11 vs 1.28 ± 0.08, P < .001) and AT (82.43 ± 7.2 vs 30.0 ± 2.8, P < .001) compared with those without stenosis. Compared with angiography, a PSV of 2.0 m/s or more and PST demonstrated a sensitivity of 91%, specificity of 96%, and overall accuracy of 92% for detection of significant renal artery stenosis. Two of five studies with false-negative results reflected diseased polar vessels. By contrast, AT of more than 100 ms had a sensitivity of 32%, specificity of 100%, and overall accuracy of 54%. Receiver operating characteristic curve analysis revealed a PSV of more than 1.8 m/s and an AT of 58 ms or greater as optimal values. With an AT of 58 ms or more, the sensitivity was 58%, and specificity was 96%, with an overall accuracy of 70%. There were no apparent associations between PSV or AT and type or location of renal artery lesion, serum creatinine level, or end-diastolic ratio. Conclusion: Main renal artery interrogation is an accurate screening test to detect significant stenosis or occlusion of the main renal artery. Hilar analysis alone does not provide sufficient sensitivity to be used as a sole screening study. Neither method detects the presence of renovascular disease associated with polar vessels.
European Heart Journal, 2008
A ratio of distal renal pressure to aortic pressure (P d /P a) ,0.90 can be considered a threshold for defining a significant renal artery stenosis (RAS). The aim of this study was to compare renal angiography (QRA) and colour duplex ultrasound (CDUS) to pressure measurements in assessing RAS. Methods and results In 56 RAS, percent diameter stenosis (DS angio), minimal luminal diameter (MLD), Doppler-derived peak systolic velocity (PSV), end-diastolic velocity (EDV), and renal-to-aortic ratio (RAR) were obtained and compared with the P d /P a measured with a 0.014" pressure wire. P d /P a correlated with angiography-and CDUS-derived parameters. The best correlation was observed with EDV (R ¼ 20.61). To identify stenosis associated with a P d /P a , 0.90, the diagnostic accuracy of DS angio. 50%, MLD , 2 mm, PSV. 180 cm/s, EDV. 90 cm/s and RAR. 3.5 were, respectively, 60%, 77%, 45%, 77% and 79%, yet, with a high proportion of false positives (38%, 15%, 55%, 11% and 15%, respectively) indicating an overestimation of the severity of the RAS by both QRA and CDUS. New cutoff values for QRA-and CDUS-derived indices were proposed. Conclusion Generally accepted QRA and CDUS-derived indices of RAS severity overestimate the actual severity of RAS. This 'overdiagnosis' is likely the main cause of the disappointing results of renal angioplasty for renovascular hypertension.
Novel Uses of Ultrasound to Assess Kidney Mechanical Properties
Kidney360
Ultrasound is a key imaging tool for evaluating the kidney. Over the last two decades, methods to measure the mechanical properties of soft tissues have been developed and used in clinical practice, although use in the kidney has not been as widespread as for other applications. The mechanical properties of the kidney are determined by the structure and composition of the renal parenchyma and perfusion characteristics. Because pathologic processes change these factors, the mechanical properties change and can be used for diagnostic purposes and for monitoring treatment or disease progression. Ultrasound-based elastography methods for evaluating the mechanical properties of the kidney use focused ultrasound beams to perturb the kidney and then high frame-rate ultrasound methods are used to measure the resulting motion. The motion is analyzed to estimate the mechanical properties. This review will describe the principles of these methods and discuss several seminal studies related to ...
Ultrasound of the Kidneys: Application of Doppler and Elastography
Ultrasound of the Kidneys: Application of Doppler and Elastography, 2019
Doppler ultrasound of the kidneys is essential in the assessment and diagnosis of kidney diseases. There are several diseases involving the kidneys. Some are functional, diffuse and systematic. Using Doppler imaging provides an assessment of vascular changes which is easily evaluated. Doppler investigation is widely used for assessment of the perfusion of renal arteries. The Doppler indexes; resistive index, pulsatility index, peak systolic are utilized for evaluating the blood flow of the renal arteries. Doppler analysis provides useful diagnostic data that can predict early damage of the kidney tissue. In recent years, ultrasound elastography showed advanced development. It is a new promising technique that is used for assessing the renal tissue characterization. Elastography is an effective imaging for assessing kidney diseases. In the future, clinicians can use elastography instead of biopsy. In this chapter, we highlighted the applications of Doppler ultrasound and elastogra-phy in evaluation of various kidney diseases.
Investigative Radiology, 2011
Objectives: Magnetic resonance elastography (MRE) allows noninvasive assessment of tissue stiffness in vivo. Renal arterial stenosis (RAS), a narrowing of the renal artery, promotes irreversible tissue fibrosis that threatens kidney viability and may elevate tissue stiffness. However, kidney stiffness may also be affected by hemodynamic factors. This study tested the hypothesis that renal blood flow (RBF) is an important determinant of renal stiffness as measured by MRE. Material and Methods: In 6 anesthetized pigs MRE studies were performed to determine cortical and medullary elasticity during acute graded decreases in RBF (by 20%, 40%, 60%, 80%, and 100% of baseline) achieved by a vascular occluder. Three sham-operated swine served as time control. Additional pigs were studied with MRE 6 weeks after induction of chronic unilateral RAS (n ϭ 6) or control (n ϭ 3). Kidney fibrosis was subsequently evaluated histologically by trichrome staining. Results: During acute RAS the stenotic cortex stiffness decreased (from 7.4 Ϯ 0.3 to 4.8 Ϯ 0.6 kPa, P ϭ 0.02 vs. baseline) as RBF decreased. Furthermore, in pigs with chronic RAS (80% Ϯ 5.4% stenosis) in which RBF was decreased by 60% Ϯ 14% compared with controls, cortical stiffness was not significantly different from normal (7.4 Ϯ 0.3 vs. 7.6 Ϯ 0.3 kPa, P ϭ 0.3), despite histologic evidence of renal tissue fibrosis. Conclusion: Hemodynamic variables modulate kidney stiffness measured by MRE and may mask the presence of fibrosis. These results suggest that kidney turgor should be considered during interpretation of elasticity assessments.
Association between kidney intracapsular pressure and ultrasound elastography
Critical care (London, England), 2017
Kidney congestion is a common pathophysiologic pathway of acute kidney injury (AKI) in sepsis and heart failure. There is no noninvasive tool to measure kidney intracapsular pressure (KIP) directly. We evaluated the correlation of KIP with kidney elasticity measured by ultrasound surface wave elastography (USWE). We directly measured transcatheter KIP in three pigs at baseline and after bolus infusion of normal saline, norepinephrine, vasopressin, dopamine, and fenoldopam; infiltration of 2-L peritoneal dialysis solution in the intra-abdominal space; and venous, arterial, and ureteral clamping. KIP was compared with USWE wave speed. Only intra-abdominal installation of peritoneal dialysis fluid was associated with significant change in KIP (mean (95% CI) increase, 3.7 (3.2-4.2)] mmHg; P < .001). Although intraperitoneal pressure and KIP did not differ under any experimental condition, bladder pressure was consistently and significantly greater than KIP under all circumstances (me...