Assessment of Angiography-Based Renal Quantitative Flow Ratio Measurement in Patients with Atherosclerotic Renal Artery Stenosis.

Background: Quantitative flow ratio (QFR) is an angiography-based fractional flow reserve measurement without pressure wire or induction of hyperemia. A recent innovation that uses combined geometrical data and hemodynamic boundary conditions to measure QFR from a single angiographic view has shown the potential to measure QFR of the renal artery-renal QFR (rQFR). Objective: The aim of this pilot study was to assess the feasibility of rQFR measurement and the contribution of rQFR in selecting patients with atherosclerotic renal artery stenosis (ARAS) undergoing revascularization. Methods: This retrospective trial enrolled patients who had ARAS (50-90%) and hypertension. The enrolled patients were treated by optimal antihypertensive medication or revascularization, respectively, and the therapeutic strategies were based on rFFR measurement and/or clinical feature. Results: A total of 55 patients underwent rQFR measurement. Among the enrolled patients, 18 underwent optimal antihypertensive medication and 37 underwent revascularization, 19 patients in whom rQFR and rFFR were both assessed. During the 180-day follow-up, 25 patients saw an improvement in their blood pressure among the 37 patients that underwent revascularization. ROC analysis revealed that rQFR had a high diagnostic accuracy for predicting blood pressure improvement (AUCrQFR = 0.932, 95% CI 0.798-0.998). The ideal cut-off value of rQFR for predicting blood pressure improvement after revascularization is ≤0.72 (sensitivity: 72.00%, specificity: 100%). The paired t test and Bland-Altman analyses demonstrated good agreement between rQFR and rFFR (t = 1.887, 95% CI -0.021 to 0.001, 95% limits of agreement: -0.035 to 0.055, p = 0.075). The Spearman correlation test reveals that there was a significant positive correlation between rQFR and rFFR (r = 0.952, 95% CI 0.874 to 0.982, p < 0.001). Conclusion: The rQFR has the potential to enhance the ability of angiography to detect functionally significant renal artery stenosis during angiography and to produce results that are comparable to invasive hemodynamic assessment.

Guidelines on the diagnosis, treatment and management of visceral and renal arteries aneurysms: a joint assessment by the Italian Societies of Vascular and Endovascular Surgery (SICVE) and Medical and Interventional Radiology (SIRM).

The objective of these Guidelines is to provide recommendations for the classification, indication, treatment and management of patients suffering from aneurysmal pathology of the visceral and renal arteries. The methodology applied was the GRADE-SIGN version, and followed the instructions of the AGREE quality of reporting checklist. Clinical questions, structured according to the PICO (Population, Intervention, Comparator, Outcome) model, were formulated, and systematic literature reviews were carried out according to them. Selected articles were evaluated through specific methodological checklists. Considered Judgments were compiled for each clinical question in which the characteristics of the body of available evidence were evaluated in order to establish recommendations. Overall, 79 clinical practice recommendations were proposed. Indications for treatment and therapeutic options were discussed for each arterial district, as well as follow-up and medical management, in both candidate patients for conservative therapy and patients who underwent treatment. The recommendations provided by these guidelines simplify and improve decision-making processes and diagnostic-therapeutic pathways of patients with visceral and renal arteries aneurysms. Their widespread use is recommended.

The performance of duplex ultrasonography for the assessment of renal artery stenosis in Takayasu's arteritis patients.

BACKGROUND: This study intends to analyze the hemodynamic parameters of the renal artery in patients with Takayasu's arteritis (TAK) to explore the diagnostic efficacy of duplex ultrasonography in assessing the involved renal artery in TAK patients. METHODS: One hundred fifteen TAK patients with 314 renal arteries were retrospectively analyzed, who were admitted to Peking Union Medical College Hospital between 2017 and 2022. These patients underwent both renal artery ultrasonography and angiography within a 4-week period. Specifically, the study compared seven ultrasonic parameters across groups categorized by the severity of renal artery stenosis (RAS), including noninvolvement, < 50% stenosis, 50-69% stenosis, and 70-99% stenosis. Receiver operating characteristic (ROC) curves were employed to determine the optimal threshold values for renal artery peak systolic velocity (RPSV), renal-aortic PSV ratio (RAR), and renal-interlobar PSV ratio (RIR) in order to diagnose various degrees of RAS in TAK patients. RESULTS: Statistically significant differences were observed in RAR and RIR among the four groups (all P < 0.05). However, no statistically significant differences were found in RPSV and AT between the moderate stenosis group (50-69% stenosis) and the severe stenosis group (70-99% stenosis). The discrimination of interlobar PSV (IPSV) and interlobar RI (IRI) was not significant, and IEDV did not show statistical significance among the four groups. For TAK patients, the recommended thresholds of RPSV for the diagnosis of renal artery involvement (RAI), ≥ 50% RAS, and ≥ 70% RAS were determined to be 143 cm/s, 152 cm/s, and 183 cm/s, respectively. The sensitivities, specificities, and accuracies of these thresholds were all found to be greater than 80%. Additionally, the optimal thresholds of RIR for detecting RAI, ≥ 50% RAS, and ≥ 70% RAS were determined to be 4.6, 5.6, and 6.4, respectively, with satisfactory diagnostic efficiencies. The areas under the curve (AUCs) for RPSV and RIR were calculated to be 0.908 and 0.910, respectively, for the diagnosis of ≥ 50% RAS, and 0.876 and 0.882 for the diagnosis of ≥ 70% RAS. When the aortic PSV is greater than or equal to 140 cm/s, the RAR exhibits inadequate diagnostic efficacy. Conversely, when the aortic PSV is less than 140 cm/s, a RAR value of 2.2 or higher can be employed as the diagnostic threshold for identifying RAS of 70% or greater, with a sensitivity of 84.00%, specificity of 89.93%, and an overall accuracy of 89.08%. CONCLUSION: In the present study, it has been demonstrated that RPSV and RIR possess substantial diagnostic value as ultrasonic parameters for diagnosing RAS in TAK patients. Furthermore, when assessing the diagnostic efficacy of RAR, it is crucial to consider the severity of aortic stenosis as a determining factor.

One-stop preoperative assessment of renal vessels for living donors with 3.0 T non-contrast-enhanced magnetic resonance angiography: compared with computerized tomography angiography and surgical results.

OBJECTIVE: The study was to investigate the feasibility and accuracy of assessment for living renal donors before transplantation by using 3.0 T non-contrast-enhanced magnetic resonance angiography (NCE-MRA). METHODS: 30 renal donors were investigated and underwent computed tomography angiography (CTA) and 3.0 T NCE-MRA before nephrectomy. Two radiologists independently assessed arterial and venous anatomy and potential kidney lesions. The image quality score, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diameters and lengths of renal arteries and veins were compared between CTA and NCE-MRA. Imaging findings were compared with the surgical results served as reference standard. Agreement was assessed using κ test. The Wilcoxon test and paired sample t test were used for statistically significant differences. RESULTS: The results of image quality score for renal arteries and veins were highly consistent between the two radiologists in NCE-MRA (p < 0.001). There was no significant difference in the scores of renal arterial and venous branches between NCE-MRA and CTA (p > 0.05). The SNR and CNR of renal vessels were higher than CTA (p < 0.001). There were no statistically significant differences in the length of renal vessels measured by the two methods (p > 0.05), and the diameter was smaller than that of CTA (p < 0.05). The detection of normal renal arteries and early branches by both examination techniques was consistent with intraoperative findings. Both methods showed good consistency between the anatomical variation of renal vein and the intraoperative diagnosis (p < 0.001). CONCLUSION: 3.0 T NCE-MRA can be used for evaluation of main renal arteries and veins with high accuracy for anatomy and variation classification, and can be used for pre-operative vascular evaluation of living donor kidney transplantation. ADVANCES IN KNOWLEDGE: 3.0 T NCE-MRA can be used for evaluation of main renal arteries and veins with high accuracy for anatomy and variation classification, and can be used for pre-operative vascular evaluation of living donor kidney transplantation.

Epidemiology and management of isolated blunt renal artery injuries.

BACKGROUND: Isolated blunt renal artery injury (BRAI) is uncommon. Treatment options include observation, nephrectomy, surgical reconstruction and endovascular stenting. Over the last decade, there has been an increasing use of angiointervention techniques in vascular trauma. Previous studies reported underutilization of endovascular stenting in BRAI, in favor of observation. The aim of this study was to examine the epidemiology and assess changes in the management of isolated BRAI over the last decade. METHODS: Patients with BRAI identified from the National Trauma Data Bank (2016-2017). Deaths in the emergency department, transferral from outside hospital, and those with associated high-grade kidney injuries were excluded. Demographics, type of renal artery injury, and renal artery management were analyzed. Multivariate analysis was used to identify independent factors associated with isolated BRAI. RESULTS: During the study period, there were 1,708,076 patients with blunt trauma and 873 (0.05%) of them had BRAI. After exclusions, 563 patients with isolated BRAI who met the criteria for inclusion in the analysis. Auto versus pedestrian mechanism and male sex were associated with the highest risk for isolated BRAI. Comorbidities, such as hypertension or diabetes, were not associated with an increased risk of BRAI. Seatbelt use had a protective effect against BRAI. In the majority of patients (534, 95%), the renal artery injury was treated with observation, 23 (4%) with nephrectomy, 5 (0.9%) with endovascular stent and 1 (0.2%) with open renal artery repair. Among the 103 patients with isolated major renal artery laceration, 91.2% were treated with observation, 7.8% with nephrectomy and 1% with stenting. CONCLUSION: Isolated blunt renal artery trauma is rare. The vast majority of patients with BRAI is managed with observation with only a small number undergoing endovascular intervention. Endovascular stenting utilization has remained very low and has not changed in the last decade.

Assessment of the embolization effect of temperature-sensitive p(N-isopropylacrylamide-co-butyl methylacrylate) nanogels in the rabbit renal artery by CT perfusion and confirmed by macroscopic examination.

Transcatheter embolization is an important treatment method in clinical therapy, and vascular embolization material plays a key role in embolization. The temperature-sensitive p(N-isopropylacrylamide-co-butyl methylacrylate) (PIB) nanogel is a novel embolic agent. To evaluate the feasibility of the nanogel as a blood vessel embolization agent, we aimed to assess the effect of embolization with PIB nanogels in the rabbit renal artery by non-invasive computed tomography (CT) perfusion, macroscopic and histological examination. Ten healthy adult Japanese rabbits were used to implement RAE of PIB nanogels in their right kidneys. CT perfusion scans were performed pre- and post-treatment at various time-points (1, 4, 8, and 12 weeks). Two rabbits were euthanized and histologically examined at each time-point, and the remaining rabbits were euthanized at 12 weeks after embolization. The RAE efficacy of the nanogels was further confirmed by macroscopic and histological examination. The renal volume and renal blood flow (BF) of the right kidney were significantly decreased post-treatment compared with those pre-treatment (volume: pre, 9278 ± 1736 mm3; post 1 week, 5155 ± 979 mm3, P < 0.0001; post 4 weeks, 3952 ± 846 mm3, P < 0.0001; post 8 weeks, 3226 ± 556 mm3, P < 0.0001; post 12 weeks, 2064 ± 507 mm3, P < 0.0001. BF: pre, 530.81 ± 51.50 ml/min/100 ml; post 1 week, 0 ml/min/100 ml, P < 0.0001; post 4 weeks, 0 ml/min/100 ml, P < 0.0001; post 8 weeks, 0 ml/min/100 ml, P < 0.0001; post 12 weeks, 0 ml/min/100 ml, P < 0.0001). No revascularization or collateral circulation was observed on histological examination during this period, and PIB nanogels were dispersed in all levels of the renal arteries. Twelve weeks after embolization, CT perfusion showed no BF in the right renal artery and renal tissue, a finding that was consistent with histological examination showing complete embolization of the right renal artery with a lack of formation of collateral vessels. The effect of embolization on PIB was adequate, with good dispersion and permanency, and could be evaluated by non-invasive and quantitative CT perfusion.

Comprehensive Assessment of Human Accessory Renal Artery Periarterial Renal Sympathetic Nerve Distribution.

OBJECTIVES: The aim of this study was to understand the anatomy of periarterial nerve distribution in human accessory renal arteries (ARAs). BACKGROUND: Renal denervation is a promising technique for blood pressure control. Despite the high prevalence of ARAs, the anatomic distribution of periarterial nerves around ARAs remains unknown. METHODS: Kidneys with surrounding tissues were collected from human autopsy subjects, and histological evaluation was performed using morphometric software. An ARA was defined as an artery arising from the aorta above or below the dominant renal artery (DRA) or an artery that bifurcated within 20 mm of the takeoff of the DRA from the aorta. The DRA was defined as an artery that perfused >50% of the kidney. RESULTS: A total of 7,287 nerves from 14 ARAs and 9 DRAs were evaluated. The number of nerves was smaller in the ARA than DRA (median: 30 [interquartile range: 17.5 to 48.5] vs. 49 [interquartile range: 36 to 76]; p < 0.0001). In both ARAs and DRAs, the distance from the arterial lumen to nerve was shortest in the distal, followed by the middle and proximal segments. On the basis of the post-mortem angiography, ARAs were divided into large (≥3 mm diameter) and small (<3 mm) groups. The number of nerves was greatest in the DRA, followed by the large and small ARA groups (53 [41 to 97], 38 [25 to 53], and 24.5 [10.5 to 36.3], respectively; p = 0.001). CONCLUSIONS: ARAs showed a smaller number of nerves than DRAs, but these results were dependent on the size of the ARA. Ablation, especially in large ARAs, may allow more complete denervation with the potential to further reduce blood pressure.

One-stop assessment of renal function and renal artery in hypertensive patients with suspected renal dysfunction: non-enhanced MRI using spatial labeling with multiple inversion pulses.

OBJECTIVES: To assess whether spatial labeling with multiple inversion pulses (SLEEK) sequence can be employed as a one-stop assessment method for evaluating renal function and displaying renal artery in hypertensive patients with suspected renal dysfunction. METHODS: A total of 78 patients with suspected hypertensive renal damage were enrolled in this retrospective study. All patients underwent MRI examinations, and both SLEEK and DWI sequences were performed simultaneously. According to estimated glomerular filtration rate (eGFR), patients were divided into three groups (Group 1, eGFR> 90; Group 2, eGFR = 60-90; Group 3, eGFR< 60). Twenty-two of these patients also underwent CT angiography (CTA) examination. Comparison between CTA, DWI, and eGFR was performed to assess the value of SLEEK in evaluating renal function and displaying renal artery. RESULTS: The performance of SLEEK to display renal artery was highly consistent with the results of CTA (kappa = 0.713). The corticomedullary contrast ratio positively correlated with eGFR (p = 0.004, r = 0.322) and was significantly higher in SLEEK images than in DWI images in all three groups (p < 0.001). There was no significant difference in corticomedullary contrast ratio in SLEEK images between Group 1 and Group 2 (p = 0.285). However, the minimal renal cortical thickness, which significantly correlated with eGFR (p < 0.001, r = 0.866), was significantly different between Group 1 and Group 2 (p < 0.001). ROC analysis showed good diagnostic performance when differentiating patients with eGFR> 60 from those with eGFR< 60. CONCLUSIONS: The SLEEK sequence could evaluate simultaneously renal function through corticomedullary differentiation and renal arteries, enabling one-stop assessment in hypertensive patients with suspected renal dysfunction. KEY POINTS: • Spatial labeling with multiple inversion pulses (SLEEK) improves renal corticomedullary differentiation in hypertensive patients with renal dysfunction compared with DWI. • SLEEK clearly displays renal artery in hypertensive patients with renal dysfunction. • SLEEK could be utilized as a one-stop assessment method for evaluating renal function and renal artery in hypertensive patients.

Renal artery Doppler studies in the assessment of monochorionic, diamniotic twin pregnancies with and without twin-twin transfusion syndrome.

BACKGROUND: In monochorionic, diamniotic twin pregnancies complicated by twin-twin transfusion syndrome, imbalanced fetofetal blood shunting and discordant activation of the renin-angiotensin system result in a hypovolemic, oliguric donor twin and a hypervolemic, polyuric recipient twin. Renal artery Doppler assessments have been reported to predict oligohydramnios in singleton pregnancies; however, their value in assessing monochorionic, diamniotic twin gestations, including pregnancies complicated by twin-twin transfusion syndrome, remains unstudied. OBJECTIVE: This investigation evaluated whether renal artery Doppler parameters are different between sets of monochorionic, diamniotic twins with and without twin-twin transfusion syndrome. STUDY DESIGN: We conducted a prospective study of women with monochorionic, diamniotic twin pregnancies complicated by twin-twin transfusion syndrome and women with gestational-age matched monochorionic, diamniotic twin control pregnancies without twin-twin transfusion syndrome. For each twin, renal artery Doppler assessment was performed from a coronal view of the fetus, and pulsatility index, resistive index, and peak systolic velocity were measured. In twin pairs complicated by twin-twin transfusion syndrome, renal artery Doppler pulsatility index, resistive index, and peak systolic velocity intertwin ratios were calculated by comparing paired recipient-to-donor values. Similar ratios were calculated for control twin pairs. We compared each measurement between donors and controls and between recipients and controls. Intertwin ratios were compared between twin-twin transfusion syndrome cases and monochorionic, diamniotic controls. Our primary outcome was a comparison of renal artery Doppler pulsatility index measurement between donor fetuses in twin-twin transfusion syndrome cases and matched control twins. Secondary outcomes included comparisons of other renal artery Doppler parameters between twin-twin transfusion syndrome donor twins and controls and between twin-twin transfusion syndrome recipients and controls and comparisons of the renal artery Doppler parameter ratios between twin-twin transfusion syndrome and non-twin-twin transfusion syndrome twin pair groups. Finally, we performed a subgroup analysis involving pregnancies with twin-twin transfusion syndrome that underwent fetoscopic laser therapy and resulted in twin survivors to evaluate if laser therapy influenced renal artery Doppler findings. RESULTS: We recruited 12 donors and 12 controls. Renal artery Doppler pulsatility index and resistive index did not differ between donors and controls. However, donor renal artery Doppler peak systolic velocity (median, 14.24 [11.51-15.36]) was significantly lower than that of controls (median, 24.79 [22.46-27.03]; P<.0004). When recipient twins were compared with controls, there was no difference in renal artery Doppler pulsatility index, renal artery Doppler resistive index, or renal artery Doppler peak systolic velocity. Renal artery Doppler peak systolic velocity ratios were significantly higher among cases with twin-twin transfusion syndrome (median, 1.70 [1.53-2.02]) than controls (median, 1.06 [1.03-1.15]; P=.002). Applying a renal artery Doppler peak systolic velocity ratio cutoff of >1.35 for the diagnosis of twin-twin transfusion syndrome correctly classified 11 of 12 cases with twin-twin transfusion syndrome and all 12 controls without twin-twin transfusion syndrome (92% sensitivity and 100% specificity). Among donors with twin-twin transfusion syndrome with double survivors after undergoing laser therapy (n=4), prelaser renal artery Doppler peak systolic velocity ratios (mean, 1.46; standard deviation, 0.37) were significantly higher than postlaser renal artery Doppler peak systolic velocity ratios (mean, 0.87; standard deviation=0.37; P=.02). Postlaser intertwin renal artery Doppler peak systolic velocity ratios did not differ from control twin pairs (P=.125). CONCLUSION: Renal artery Doppler peak systolic velocity ratios differ between monochorionic, diamniotic twins with twin-twin transfusion syndrome and those without twin-twin transfusion syndrome. This effect seems to be driven by altered donor twin renal artery Doppler peak systolic velocity. Laser therapy may normalize renal artery Doppler peak systolic velocity ratios and donor twin renal artery Doppler values to those observed in monochorionic, diamniotic twins without twin-twin transfusion syndrome. Further study is warranted to explore whether renal artery Doppler peak systolic velocity has utility as a tool for twin-twin transfusion syndrome prediction, diagnosis, or staging, and fetal response to laser therapy.

Diagnostic accuracy of arterial and venous renal Doppler assessment for acute kidney injury in critically ill patients: A prospective study.

BACKGROUND AND PURPOSE: Renal Resistive Index (RRI) and Venous Impedance Index (VII) might be of additional value for diagnosing Acute Kidney Injury (AKI). The purpose of this study was to assess the diagnostic accuracy of RRI and VII for AKI. MATERIALS AND METHODS: In the prospective Simple Intensive Care Studies-II (NCT03577405), we measured RRI and VII in acutely admitted adult intensive care patients within 24 h of admission. AKI was defined by the Kidney Disease Improving Global Outcome (KDIGO) criteria. The primary outcome was persistent AKI, defined as non-resolved AKI on day three. We tested specificity, sensitivity and diagnostic accuracy of both RRI and VII for persistent AKI. RESULTS: In total, 371 patients were included of whom 123 patients (33%) had persistent AKI. RRI and VII did not differ between patients with and those without persistent AKI (p = .08 and p = .59). RRI had a moderate specificity (72%, 95%CI 66-78%) and low sensitivity (32%, 95%CI 24-41%) and VII had high sensitivity (93%, 95%CI 85-98%) and low specificity (11%, 95%CI 6-16%) for persistent AKI. Overall diagnostic accuracy of RRI and VII was moderate. CONCLUSIONS: In acutely admitted critically ill patients, measures of renal perfusion by renal ultrasound were not different between patients with and without AKI, and show limited diagnostic accuracy for AKI. Registered:NCT03577405.

Assessment of renal vascular anatomy on multi-detector computed tomography in living renal donors.

BACKGROUND: Prospective renal donors are a select population of healthy individuals who have been thoroughly screened for significant comorbidities before they undergo multi-detector computed tomography angiography and urography (MDCT). PURPOSE: The aim of this study is to describe the anatomy of potential living renal donor subjects using MDCT over a 2-year period. The primary objective is to identify the renal arterial anatomy variations, with a secondary objective of identifying venous and collecting system/ureteric variations. MATERIALS AND METHODS: A prospective study was performed of prospective living kidney transplant donors at a national kidney transplant centre. Study inclusion criteria were all potential kidney donors who underwent MDCT during the living-donor assessment process over a 2-year period. RESULTS: Our cohort included 160 potential living donors who had MDCT; mean age was 45.6 years (range, 21-71). Two renal arteries were identified on the left in 40 subjects (25%) and on the right in 42 subjects (26.3%). A total of 3 or more renal arteries were identified on the left in 7 subjects (4.4%) and on the right in 7 subjects (4.4%). On the left, the distances between multiple arteries ranged from 1 mm to 43 mm, and on the right, they were 1 mm to 84 mm. CONCLUSIONS: Conventionally described anatomy was only seen on the left side in 70.6% and 69.4% on the right side of subjects. Single renal arteries are seen in 54.4% showing that conventional anatomy has a relatively low incidence.

Preoperative assessment system for hand-assisted laparoscopic donor nephrectomy by discriminant analysis.

We developed a preoperative assessment system to predict surgical workload in hand-assisted laparoscopic donor nephrectomy (HALDNx) using the normal-based linear discriminant rule (NLDR). A total of 128 cases of left HALDNx performed by a single operator were used as training data. Surgical workload was measured by operative time. The optimized model had 9 explanatory variables: age, total protein, total cholesterol, number of renal arteries (numberRA), 4 variables of perinephric fat (PNF), and thickness of subcutaneous fat. This model was validated using cross-validation and the .632 estimator to estimate discrimination rates with future test data. PNF and numberRA were the predominant factors affecting workload followed by the computed tomography value of PNF, body weight, and male sex. The estimated accuracy of the prediction system was 94.6%. The complication rate was 9.38% and did not correlate with surgical workload. We also made our program available online for constructing assessment functions from other cohort data. In conclusion, the surgical workload of HALDNx could be predicted with PNF and numberRA as the dominant risk factors.

[Anatomical Variation of the Origin of the Right Renal Artery : Assessment with an Angle of the Origin and Ventral Protrusion].

The right renal artery has been considered to originate laterally from the anterior aspect of aorta. In some cases, it turns more ventrally than the aorta, which can lead to intraoperative right renal artery injury. For this reason, we evaluated how the right renal artery turns ventrally and analyzed the factors for ventral protrusion of the right renal artery. We examined contrast-enhanced computed tomography images of 195 individuals and measured their angles of the right renal artery and ventral protrusion from the aorta. Age and sex had no significant correlation with these variations. A weaknegative correlation was found between body mass index and these variations. Almost all the right renal artery originated from the ventral side of the aorta, and almost half the right renal artery arose ventrally more than the aorta. Careful attention should be paid to ventral protrusion of the right renal artery to prevent vascular injury during surgery using the anterior approach to the upper retroperitoneum.

Renal artery assessment with non-enhanced MR angiography versus digital subtraction angiography: comparison between 1.5 and 3.0 T.

OBJECTIVES: To compare non-enhanced magnetic resonance angiography (NE-MRA) between 1.5 and 3.0-T using a balanced steady-state free precession (bSSFP) sequence in the assessment of renal artery stenosis (RAS) with digital subtraction angiography (DSA) as a reference standard. METHODS: From March 2016 to May 2018, 81 patients suspected to have significant RAS were scheduled for DSA. All patients underwent NE-MRA at either 1.5 T or 3.0 T randomly before DSA. In total, 49 patients underwent 1.5-T NE-MRA, and 32 patients underwent 3.0-T NE-MRA. Image quality was assessed. Degree of stenosis evaluated with NE-MRA was compared with that with DSA. RESULTS: NE-MRA provided excellent image qualities for segment 1 and segment 2 at 1.5 T and 3.0 T. Image qualities for segment 3 and segment 4 and the degree of renal artery branches were significantly higher at 3.0 T than at 1.5 T (p < 0.01). Stenoses evaluated with NE-MRA at 1.5 T (r = 0.853, p < 0.01) and 3.0 T (r = 0.811, p < 0.01) were highly correlated with those of DSA. The Bland-Altman plots showed overestimated degrees of stenosis at 1.5 T (mean bias, 3.5% ± 20.4) and 3.0 T (mean bias, 8.4% ± 21.7). The sensitivity and specificity for significant stenosis were 97.4% and 89.8% for 1.5 T and 95.7% and 91.1% for 3.0 T. CONCLUSIONS: Both 1.5-T and 3.0-T bSSFP NE-MRA can reliably assess RAS, with high image quality and good diagnostic accuracy. Performing NE-MRA at 3.0 T significantly improved visualization of renal artery branches but showed greater tendency to overestimate stenosis compared with that at 1.5 T. KEY POINTS: • Both 1.5-T and 3.0-T NE-MRA provide excellent image quality and good diagnostic accuracy for RAS. • NE-MRA at 3.0 T improved visualization of renal artery branches compared with that at 1.5 T.

An assessment of the utility and repeatability of the renal resistive index in horses.

The aim of this study was to establish the value of the renal resistive index (RI) of intrarenal arteries in healthy warmblood non-racing horses of different ages to assess the influence of physiologic factors and repeatability of measurement. The kidney ultrasonography examination was performed in three age groups: 15 foals, 15 adults and 15 elderly horses. The procedure was performed in unsedated standing animals. RI values were measured using pulsed-wave Doppler at the medial part of each kidney in the intrarenal arteries. To evaluate repeatability, all measurements were repeated two hours after the first examination. Statistical analysis of the relationship between groups was carried out using Fisher's test. The relationship between the RI value and the physiological parameters was evaluated using linear regression. Repeatability of measurements was determined based on the Bland-Altman plot. The mean RI value in the studied horses was 0.48 ± 0.05 in the left kidney and 0.49 ± 0.05 in the right kidney. There were no statistically significant differences between the RI values in foals and adult horses. The elderly horses had a significantly higher RI value. Pulse pressure was the only physiological parameter affecting the RI value. The repeatability coefficient was 0.089 for the right kidney and 0.09 for the left kidney. The presented result suggest that elderly healthy horses have higher RI values than younger animals, which should be taken into account in clinical practice. The arterial pulse pressure should also be considered when interpreting RI values. The measurements have high repeatability, but in the authors' opinion, this procedure is time consuming and requires experience.

[Secondary hypertension in women]. / HTA secondaires chez la femme.

The two main non-iatrogenic causes of secondary hypertension in women of childbearing age are primary aldosteronism and renal fibromuscular dysplasia. It is recommended to look for a secondary hypertension in women who remain hypertensive three months after pregnancy, in patients under 40 years of age or in patients with a grade 3 HTN (BP≥180/110mm Hg) (Professional agreement). It is suggested that the initial assessment of a secondary HTN in women is performed by a HTN specialist; it will include an assessment of renin and aldosterone concentrations and an angio-CT of the renal arteries (or angio-MRI if contraindicated) (Grade C - Class 2).

Image quality and pathology assessment in CT Urography: when is the low-dose series sufficient?

BACKGROUND: Our aim was to compare CT images from native, nephrographic and excretory phases using image quality criteria as well as the detection of positive pathological findings in CT Urography, to explore if the radiation burden to the younger group of patients or patients with negative outcomes can be reduced. METHODS: This is a retrospective study of 40 patients who underwent a CT Urography examination on a 192-slice dual source scanner. Image quality was assessed for four specific renal image criteria from the European guidelines, together with pathological assessment in three categories: renal, other abdominal, and incidental findings without clinical significance. Each phase was assessed individually by three radiologists with varying experience using a graded scale. Certainty scores were derived based on the graded assessments. Statistical analysis was performed using visual grading regression (VGR). The limit for significance was set at p = 0.05. RESULTS: For visual reproduction of the renal parenchyma and renal arteries, the image quality was judged better for the nephrogram phase (p < 0.001), whereas renal pelvis/calyces and proximal ureters were better reproduced in the excretory phase compared to the native phase (p < 0.001). Similarly, significantly higher certainty scores were obtained in the nephrogram phase for renal parenchyma and renal arteries, but in the excretory phase for renal pelvis/calyxes and proximal ureters. Assessment of pathology in the three categories showed no statistically significant differences between the three phases. Certainty scores for assessment of pathology, however, showed a significantly higher certainty for renal pathology when comparing the native phase to nephrogram and excretory phase and a significantly higher score for nephrographic phase but only for incidental findings. CONCLUSION: Visualisation of renal anatomy was as expected with each post-contrast phase showing favourable scores compared to the native phase. No statistically significant differences in the assessment of pathology were found between the three phases. The low-dose CT (LDCT) seems to be sufficient in differentiating between normal and pathological examinations. To reduce the radiation burden in certain patient groups, the LDCT could be considered a suitable alternative as a first line imaging method. However, radiologists should be aware of its limitations.

Morphological assessment of cat kidneys using computed tomography.

There are numerous publications about feline renal imaging information; however, none have established reference values for kidney size using computed tomography (CT). This study aimed to determine renal size and shape as well as the morphology of renal-related structures in clinically normal cats (Felis catus) that underwent CT. Twenty-seven healthy cats underwent pre- and post-iodinated contrast-enhanced CT. Most cat (59%) kidneys were located at the same level. The average pre-contrast dimensions of the left kidney included a width of 2.46 ± 0.28 cm, a length of 3.52 ± 0.44 cm and a height 2.19 ± 0.31 cm, whereas those of the right kidneys were 2.45 ± 0.27 cm, 3.54 ± 0.46 cm and 2.05 ± 0.23 cm, respectively. After contrast enhancement, kidneys were slightly enlarged though not significantly. Additionally, renal length (LK or RK) was compared with second lumbar vertebra (L2) length and abdominal aorta diameter (AO). AO was significantly larger in male cats whereas L2 length appeared longer in male cats, but was not statistically different from the female cats. The LK/L2 and RK/L2 ratios were 2.29 ± 0.23 and 2.36 ± 0.20, respectively, and the LK/AO and RK/AO were 11.72 ± 1.37 and 12.05 ± 1.47, respectively. Renal vessels were examined. The renal vein was obviously larger than the renal artery, and paired renal veins were observed periodically. This study provides CT information about the feline kidney, which may help to establish reference values and information regarding renal structure prior to surgery in practice.

Assessment of surgical skills by using surgical navigation in robot-assisted partial nephrectomy.

PURPOSE: To assess surgical skills in robot-assisted partial nephrectomy (RAPN) with and without surgical navigation (SN). METHODS: We employed an SN system that synchronizes the real-time endoscopic image with a virtual reality three-dimensional (3D) model for RAPN and evaluated the skills of two expert surgeons with regard to the identification and dissection of the renal artery (non-SN group, n = 21 [first surgeon n = 9, second surgeon n = 12]; SN group, n = 32 [first surgeon n = 11, second surgeon n = 21]). We converted all movements of the robotic forceps during RAPN into a dedicated vocabulary. Using RAPN videos, we classified all movements of the robotic forceps into direct action (defined as movements of the robotic forceps that directly affect tissues) and connected motion (defined as movements that link actions). In addition, we analyzed the frequency, duration, and occupancy rate of the connected motion. RESULTS: In the SN group, the R.E.N.A.L nephrometry score was lower (7 vs. 6, P = 0.019) and the time to identify and dissect the renal artery (16 vs. 9 min, P = 0.008) was significantly shorter. The connected motions of inefficient "insert," "pull," and "rotate" motions were significantly improved by SN. SN significantly improved the frequency, duration, and occupancy rate of connected motions of the right hand of the first surgeon and of both hands of the second surgeon. The improvements in connected motions were positively associated with SN for both surgeons. CONCLUSION: This is the first study to investigate SN for nephron-sparing surgery. SN with 3D models might help improve the connected motions of expert surgeons to ensure efficient RAPN.

Rationale and study design for one-stop assessment of renal artery stenosis and renal microvascular perfusion with contrast-enhanced ultrasound for patients with suspected renovascular hypertension.

BACKGROUND: Renal artery stenosis (RAS) is always associated with abnormalities in renal microvascular perfusion (RMP). However, few imaging methods can simultaneously evaluate the degree of luminal stenosis and RMP. Thus, this study will aim to evaluate the feasibility of using contrast-enhanced ultrasound (CEUS) for assessing both RAS and RMP to achieve a one-stop assessment of patients with suspected renovascular hypertension. METHODS: This will be a single-center diagnostic study with a sample size of 440. Patients with chronic kidney disease (CKD) and suspected of having resistant hypertension will be eligible. Patients with Stages 1-3 CKD will undergo CEUS and computed tomography (CT) angiography (CTA). Values obtained by CEUS and CTA for diagnosing low-grade (lumen reduced by <60%) and high-grade (lumen reduced by ≥60%) RAS will be compared. Moreover, all patients will also undergo radionuclide imaging. The diagnostic value for RAS will be assessed by the receiver operating characteristic curve, including the accuracy, sensitivity, specificity, positive predictive values, negative predictive values, and area under the ROC. Pearson correlation analysis will be performed to assess the association between CEUS findings for RMP and glomerular filtration rate measured by a radionuclide imaging method. CONCLUSION: The data gathered from this study will be used to evaluate the feasibility of expanding clinical applications of CEUS for evaluation of patients with suspected renovascular hypertension. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1800016252; https://www.chictr.org.cn.