Variation coefficient of stone density and renal cortical thickness: the parameters evaluating non-contrast computed tomography imaging for predict extracorporeal shock wave lithotripsy success.

The stone density (SD) is not the same in all parts of the stone due to the heterogeneous nature of the stone and the shock wave (SW) passes through tissues of many different densities until it reaches the stone. These factors affect the success of Extracorporeal Shock Wave Lithotripsy (ESWL). We aimed to evaluate the effect of the Variation Coefficient of Stone Density (VCSD) and Renal Cortical Tickness (RCT) on the success of ESWL. Between 2020 and 2023, 510 patients who underwent ESWL were divided into 2 groups treatment success (n:304) and treatment failure (n:206). Non-Contrast Computed Tomography (NCCT) imaging values of hydronephrosis degree of the kidney, stone location, stone volume (SV), stone-skin distance (SSD), SD, Standard deviation of Stone Density (SDSD), VCSD, RCT, Soft-Tissue Thickness (STT), Muscle Thickness (MT) were analyzed. VCSD value was obtained by dividing SDSD by SD. Along the SW, tissues were divided into three components: kidney (renal cortex), muscle and other soft tissues. RCT, MT and SSD were measured at three different angles (0°, 45°, and 90°) and these 3 lengths were averaged. In univariate analysis, Body Mass Index (BMI), SV, SD, VCSD, SSD, RCT and STT were demonstrated to affect ESWL success. In multivariate analysis, low BMI, SV, SD, RCT and large VCSD were significant independent predictors of ESWL success. Among these parameters, VCSD had the highest prediction accuracy, followed by SD, SV, RCT and BMI, respectively. This study demonstrated that VCSD value and RCT are predictive parameters in determining the treatment of patients with urinary calculi and selecting suitable ESWL candidates.

An Objective Computer-Assisted Measurement of Sonographic Renal Cortical Echogenicity: The Splenorenal Index.

ABSTRACT: Renal cortical echogenicity represents a marker of renal function. However, evaluation of the renal echotexture is subjective and thus disposed to error and interrater variability. Computer-aided image analysis may be used to objectively assess renal cortical echogenicity by comparing the echogenicity of the left kidney to that of the spleen; the resultant ratio is referred to as the splenorenal index (SRI). We performed a retrospective review of all adult patients who received a renal ultrasound over a 45-day period at our institution. Demographic data and kidney function laboratory values were documented for each patient. Regions of interest (ROIs) were selected in the left renal cortex and spleen using ImageJ software. The SRI was calculated as a ratio of the mean pixel brightness of the left kidney cortex ROI to the mean pixel brightness of the spleen ROI. The SRI was then correlated with serum creatinine, blood urea nitrogen, and estimated glomerular filtration rate. We found that among the 94 patients included in the study, the SRI had a significant positive correlation with serum creatinine ( r = 0.43, P < 0.001) and serum blood urea nitrogen ( r = 0.45, P < 0.001) and negative correlation with estimated glomerular filtration rate ( r = -0.47, P < 0.001). Our data indicate that SRI may serve as a valuable tool for sonographic evaluation of renal parenchymal disease.

Effects of Norepinephrine on Renal Cortical and Medullary Blood Flow in Atherosclerotic Rabbits.

OBJECTIVE: The aim of this study was to explore the effect of norepinephrine (NE) on renal cortical and medullary blood flow in atherosclerotic rabbits without renal artery stenosis. METHODS: Atherosclerosis was induced in 21 New Zealand white rabbits by feeding them a cholesterol-rich diet for 16 weeks. Thirteen healthy New Zealand white rabbits were randomly selected as controls. After atherosclerosis induction, standard ultrasonography was performed to confirm that there was no plaque or accelerated flow at the origin of the renal artery. Contrast-enhanced ultrasound (CEUS) was performed at baseline and during intravenous injection of NE. The degree of contrast enhancement of renal cortex and medulla after the injection of contrast agents was quantified by calculating the enhanced intensity. RESULTS: The serum nitric oxide (NO) level in atherosclerotic rabbits was higher than that in healthy rabbits (299.6±152 vs. 136.5±49.5, P<0.001). The infusion of NE induced a significant increase in the systolic blood pressure (112±14 mmHg vs. 84±9 mmHg, P=0.016) and a significant decrease in the enhanced intensity in renal cortex (17.78±2.07 dB vs. 21.19±2.03 dB, P<0.001) and renal medulla (14.87±1.82 dB vs. 17.14±1.89 dB, P<0.001) during CEUS. However, the enhanced intensity in the cortex and medulla of healthy rabbits after NE infusion showed no significant difference from that at baseline. CONCLUSION: NE may reduce renal cortical and medullary blood flow in atherosclerotic rabbits without renal artery stenosis, partly by reducing the serum NO level.

Detection of impaired renal allograft function in paediatric and young adult patients using arterial spin labelling MRI (ASL-MRI).

The study aimed to discriminate renal allografts with impaired function by measuring cortical renal blood flow (cRBF) using magnetic resonance imaging arterial spin labelling (ASL-MRI) in paediatric and young adult patients. We included 18 subjects and performed ASL-MRI on 1.5 T MRI to calculate cRBF on parameter maps. cRBF was correlated to calculated glomerular filtration rate (GFR) and compared between patient groups with good (GFR ≥ 60 mL/min/1.73 m2) and impaired allograft function (GFR < 60 mL/min/1.73 m2). Mean cRBF in patients with good allograft function was significantly higher than in patients with impaired allograft function (219.89 ± 57.24 mL/min/100 g vs. 146.22 ± 41.84 mL/min/100 g, p < 0.008), showing a highly significant correlation with GFR in all subjects (r = 0.75, p < 0.0001). Also, the diffusion-weighted imaging (DWI-MRI) apparent diffusion coefficient (ADC) and Doppler measurements of peak-systolic and end-diastolic velocities and the resistive index (PS, ED, RI) were performed and both methods showed no significant difference between groups. ADC implied no correlation with GFR (r = 0.198, p = 0.464), while PS indicated moderate correlation to GFR (r = 0.48, p < 0.05), and PS and ED moderate correlation to cRBF (r = 0.58, p < 0.05, r = 0.56, p < 0.05, respectively). Cortical perfusion as non-invasively measured by ASL-MRI differs between patients with good and impaired allograft function and correlates significantly with its function.

Automated Segmentation of Kidney Cortex and Medulla in CT Images: A Multisite Evaluation Study.

BACKGROUND: In kidney transplantation, a contrast CT scan is obtained in the donor candidate to detect subclinical pathology in the kidney. Recent work from the Aging Kidney Anatomy study has characterized kidney, cortex, and medulla volumes using a manual image-processing tool. However, this technique is time consuming and impractical for clinical care, and thus, these measurements are not obtained during donor evaluations. This study proposes a fully automated segmentation approach for measuring kidney, cortex, and medulla volumes. METHODS: A total of 1930 contrast-enhanced CT exams with reference standard manual segmentations from one institution were used to develop the algorithm. A convolutional neural network model was trained (n=1238) and validated (n=306), and then evaluated in a hold-out test set of reference standard segmentations (n=386). After the initial evaluation, the algorithm was further tested on datasets originating from two external sites (n=1226). RESULTS: The automated model was found to perform on par with manual segmentation, with errors similar to interobserver variability with manual segmentation. Compared with the reference standard, the automated approach achieved a Dice similarity metric of 0.94 (right cortex), 0.90 (right medulla), 0.94 (left cortex), and 0.90 (left medulla) in the test set. Similar performance was observed when the algorithm was applied on the two external datasets. CONCLUSIONS: A fully automated approach for measuring cortex and medullary volumes in CT images of the kidneys has been established. This method may prove useful for a wide range of clinical applications.

Remnant renal volume can predict prognosis of remnant renal function in kidney transplantation donors: a prospective observational study.

BACKGROUND: Safety and survival during and after donor nephrectomy (DN) are one of the main concerns in living kidney donors (LKDs). Therefore, kidney (left/right) to be procured should be determined after considering the difficulty of DN, as well as the preservation of remnant renal function (RRF). In this prospective study, we investigated the roles of computed tomography volumetry (CTV) in split renal function (SRF) and established a predictive model for RRF in LKDs. METHODS: We assessed 103 LKDs who underwent DN at our institute. The Volume Analyzer SYNAPSE VINCENT image analysis system were used as CTV. RRF was defined as the estimated glomerular filtration rate (eGFR) 12 months after DN. The association between various factors measured by CTV and RRF were investigated, and a role of CTV on prediction for RRF was assessed. RESULTS: The median age and the preoperative eGFR were 58 years and 80.7 mL/min/1.73m2, respectively. Each factor measured by CTV showed an association with RRF. The ratio of remnant renal volume to body surface area (RRV/BSA) could predict RRF. In addition, RRV/BSA could predict RRF more accurately when used together with age and 24-h creatinine clearance (CrCl). CONCLUSIONS: Our findings suggest that RRV/BSA measured by CTV can play an important role in predicting RRF, and a comprehensive assessment including age and CrCl is important to determine the kidney to be procured.

Quantitative Evaluation of Renal Cortex Perfusion Using Contrast-Enhanced Ultrasound Imaging Parameters in Ischemia-Reperfusion Injury in Rabbits.

The aim of this study was to evaluate blood perfusion of the renal cortex during ischemia-reperfusion (I/R) injury using quantitative contrast-enhanced ultrasound (CEUS) parameters. In this experiment, 24 rabbits were randomly divided into four groups (N = 6): sham-operated group, 24-h post-operation for I/R injury group (24-h I/R), 3-d post-operation for I/R injury group (3-d I/R) and 5 d post-operation for I/R injury group (5 d I/R). All quantitative CEUS parameters were monitored and included the gradient from the start frame to the peak frame (Grad), area under the curve (Area), time-to-peak (TTP), difference between B(intercept intensity at t=0) and A(the intensity attenuation t= 0) and arrival time (AT). Subsequently, we analyzed the changes in these parameters, as well as the correlation between changes in CEUS parameters and pathological parameters. AT and TTP values peaked 3 d after I/R surgery, which correlated with the most significant pathological changes at the same time point. These parameters (such as AT, TTP and Grad) may be useful in dynamically monitoring the severity of tissue damage at the early stage of I/R injury.

Renal Cortical Perfusion Estimated in Color Doppler Dynamic Tissue Perfusion Measurement in Patients Treated with Levothyroxine Following Total Thyroidectomy for Resectable Thyroid Cancer Is Independently Associated with Free Thyroxine: A Single-Center Prospective Study.

BACKGROUND The thyroid state significantly influences renal function. However, a direct link between thyroid and kidney dysfunction has not been identified. Thyroid hormones affect cardiac output and vascular resistance, and thus can modify kidney perfusion. This prospective study aimed to test the association between renal cortical perfusion (RCP) estimated in color Doppler sonographic dynamic tissue perfusion measurement (DTPM) with thyroid hormones in 36 patients treated with levothyroxine following total thyroidectomy for resectable thyroid cancer. MATERIAL AND METHODS Blood tests, blood pressure monitoring, and DTPM of the renal cortex were performed. To exclude possible reading errors, the intrarater reliability of the ultrasound perfusion measurement method was estimated. RESULTS The absolute difference between the 2 ultrasound RCP measurements was 5.2±4.4%. RCP correlated significantly with free thyroxine (FT4) (r=0.46; p=0.006) but not with triiodothyronine and thyroid-stimulating hormone. In the adjusted to age backward stepwise multivariable regression analysis model, including estimated glomerular filtration rate, mean arterial pressure, and FT4, only FT4 was independently associated with RCP (R²=0.21; p=0.006). CONCLUSIONS Renal cortical perfusion is independently associated with free thyroxine, which can contribute to renal function abnormalities in the condition of impaired thyroid function. This small prospective study from a single center showed that the renal cortex's color Doppler sonographic dynamic tissue perfusion measurement had very good intraobserver reproducibility.

[CME Sonography 99/Answers: Kidney Echo Changes]. / CME-Sonografie 99/Antworten: Veränderungen der Nierenechogenität.

CME Sonography 99/Answers: Kidney Echo Changes Abstract. Normal kidneys have a smooth contour, kidney length 9-12 cm, volume 90-180 ml/1.73 m2 body surface, parenchyma width 13-18 mm and an echogenicity of the cortex which is hypoechoic compared to the liver and spleen, as well as medullary pyramids, which are again hypoechoic compared to the cortex. Digital ultrasound images enable the echogenicity to be measured between 0 (black) and 255 (white). A normal quotient between the echogenicity of the liver and the renal cortex is 1.0-1.4. A normal quotient between the spleen and the renal cortex is> 1.0. The normal quotient between the renal cortex and the renal medulla is> 1.0. In diffuse renal parenchyma diseases, changes in echogenicity are observed. There are kidneys with increased echogenicity of the cortex and a ratio to liver and spleen of <1.0 and kidneys with hyperechoic renal medulla and the ratio between renal cortex and renal medulla <1.0.

[CME Sonography 99: Kidney Echo Changes]. / CME-Sonografie 99: Veränderungen der Nierenechogenität.

CME Sonography 99: Kidney Echo Changes Abstract. Normal kidneys have a smooth contour, kidney length 9-12 cm, volume 90-180 ml/1.73 m2 body surface, parenchyma width 13-18 mm and an echogenicity of the cortex which is hypoechoic compared to the liver and spleen, as well as medullary pyramids, which are again hypoechoic compared to the cortex. Digital ultrasound images enable the echogenicity to be measured between 0 (black) and 255 (white). A normal quotient between the echogenicity of the liver and the renal cortex is 1.0-1.4. A normal quotient between the spleen and the renal cortex is >1.0. The normal quotient between the renal cortex and the renal medulla is >1.0. In diffuse renal parenchyma diseases, changes in echogenicity are observed. There are kidneys with increased echogenicity of the cortex and a ratio to liver and spleen of <1.0 and kidneys with hyperechoic renal medulla and the ratio between renal cortex and renal medulla <1.0.

Assessment of chronic allograft injury in renal transplantation using diffusional kurtosis imaging.

BACKGROUND: Chronic allograft injury (CAI) is a significant reason for which many grafts were lost. The study was conducted to assess the usefulness of diffusional kurtosis imaging (DKI) technology in the non-invasive assessment of CAI. METHODS: Between February 2019 and October 2019, 110 renal allograft recipients were included to analyze relevant DKI parameters. According to estimated glomerular filtration rate (eGFR) (mL/min/ 1.73 m2) level, they were divided to 3 groups: group 1, eGFR ≥ 60 (n = 10); group 2, eGFR 30-60 (n = 69); group 3, eGFR < 30 (n = 31). We performed DKI on a clinical 3T magnetic resonance imaging system. We measured the area of interest to determine the mean kurtosis (MK), mean diffusivity (MD), and apparent diffusion coefficient (ADC) of the renal cortex and medulla. We performed a Pearson correlation analysis to determine the relationship between eGFR and the DKI parameters. We used the receiver operating characteristic curve to estimate the predicted values of DKI parameters in the CAI evaluation. We randomly selected five patients from group 2 for biopsy to confirm CAI. RESULTS: With the increase of creatinine, ADC, and MD of the cortex and medulla decrease, MK of the cortex and medulla gradually increase. Among the three different eGFR groups, significant differences were found in cortical and medullary MK (P = 0.039, P < 0.001, P < 0.001, respectively). Cortical and medullary ADC and MD are negatively correlated with eGFR (r = - 0.49, - 0.44, - 0.57, - 0.57, respectively; P < 0.001), while cortical and medullary MK are positively correlated with eGFR (r = 0.42, 0.38; P < 0.001). When 0.491 was set as the cutoff value, MK's CAI assessment showed 87% sensitivity and 100% specificity. All five patients randomly selected for biopsy from the second group confirmed glomerulosclerosis and tubular atrophy/interstitial fibrosis. CONCLUSION: The DKI technique is related to eGFR as allograft injury progresses and is expected to become a potential non-invasive method for evaluating CAI.

Ultrasound Findings and Laboratory Predictors of Early Mortality in Patients With Severe Yellow Fever.

OBJECTIVE. Yellow fever is a hemorrhagic disease caused by an arbovirus endemic in South America; outbreaks have occurred in recent years. The purpose of this study was to describe abdominal ultrasound findings in patients with severe yellow fever and correlate them with clinical and laboratory data. MATERIALS AND METHODS. A retrospective cohort study was performed between January and April 2018. The subjects were patients admitted to an ICU with polymerase chain reaction-confirmed yellow fever. Bedside sonography was performed within 48 hours of admission. Images were independently analyzed by two board-certified radiologists. Laboratory test samples were collected within 12 hours of image acquisition. Multivariable logistic regression analysis was performed to identify 30-day mortality predictors; p < .05 was considered statistically significant. RESULTS. Forty-six patients (40 [87%] men, six [13%] women; mean age, 47.5 ± 15.2 years) were evaluated with bedside sonography. Laboratory tests showed high serum levels of aspartate aminotransferase (5319 U/L), total bilirubin (6.2 mg/dL), and creati-nine (4.3 mg/dL). Twenty-six (56.5%) patients died within 30 days of admission (median time to death, 5 days [interquartile range, 2-9 days]). The most frequent ultrasound findings were gallbladder wall thickening (80.4%), increased renal cortex echogenicity (71.7%), increased liver parenchyma echogenicity (65.2%), perirenal fluid (52.2%), and ascites (30.4%). Increased renal echogenicity was associated with 30-day mortality (84.6% versus 55.0%; p = .046) and was an independent predictor of this outcome after multivariate analysis (odds ratio, 10.89; p = .048). CONCLUSION. Reproducible abdominal ultrasound findings in patients with severe yellow fever may be associated with severity of disease and prognosis among patients treated in the ICU.

Does the renal parenchymal thickness affect the efficacy of the retrograde intrarenal surgery? A prospective cohort study.

Retrograde intrarenal surgery (RIRS) is one of the minimally invasive main treatment modalities in renal stone disease. There are many factors which affect stone-free rate (SFR). Our study was based on the hypothesis that higher renal parenchymal thickness (RPT) which may include higher average number of nephrons provides better diuresis. We investigated the efficacy of RPT on success of RIRS. This study is a single-centered prospective surgical cohort study. A total of 383 patients were analyzed. Regularly followed 304 patients with unilateral kidney stone at single pole or renal pelvis and who underwent single-session RIRS were included in the final analysis, and the patients' preoperative and postoperative 1st and 3rd months' data were evaluated. RPT was measured on the non-contrast computed tomography (CT) images. ROC analysis was performed to estimate the cutoff value of RPT for SFR. Univariate and multivariate logistic regression analyses were used to model the relationship between RPT and SFR after RIRS. ROC analysis revealed the best cutoff value of the RPT for predicting residual stone as 19 mm for both the 1st and 3rd month visits with Youden indexes of 0.397 and 0.406, respectively. To the best of our knowledge, this is the first study which evaluated the effect of RPT on the efficacy of RIRS. RPT measurement is a cost-effective method that can be easily performed on routinely applied non-contrast CT and may have predictive value for the surgical success in patients with nephrolithiasis.

Development and evaluation of deep learning-based segmentation of histologic structures in the kidney cortex with multiple histologic stains.

The application of deep learning for automated segmentation (delineation of boundaries) of histologic primitives (structures) from whole slide images can facilitate the establishment of novel protocols for kidney biopsy assessment. Here, we developed and validated deep learning networks for the segmentation of histologic structures on kidney biopsies and nephrectomies. For development, we examined 125 biopsies for Minimal Change Disease collected across 29 NEPTUNE enrolling centers along with 459 whole slide images stained with Hematoxylin & Eosin (125), Periodic Acid Schiff (125), Silver (102), and Trichrome (107) divided into training, validation and testing sets (ratio 6:1:3). Histologic structures were manually segmented (30048 total annotations) by five nephropathologists. Twenty deep learning models were trained with optimal digital magnification across the structures and stains. Periodic Acid Schiff-stained whole slide images yielded the best concordance between pathologists and deep learning segmentation across all structures (F-scores: 0.93 for glomerular tufts, 0.94 for glomerular tuft plus Bowman's capsule, 0.91 for proximal tubules, 0.93 for distal tubular segments, 0.81 for peritubular capillaries, and 0.85 for arteries and afferent arterioles). Optimal digital magnifications were 5X for glomerular tuft/tuft plus Bowman's capsule, 10X for proximal/distal tubule, arteries and afferent arterioles, and 40X for peritubular capillaries. Silver stained whole slide images yielded the worst deep learning performance. Thus, this largest study to date adapted deep learning for the segmentation of kidney histologic structures across multiple stains and pathology laboratories. All data used for training and testing and a detailed online tutorial will be publicly available.

Physiological system analysis of the kidney by high-temporal-resolution T2∗ monitoring of an oxygenation step response.

PURPOSE: Examine the feasibility of characterizing the regulation of renal oxygenation using high-temporal-resolution monitoring of the T2∗ response to a step-like oxygenation stimulus. METHODS: For T2∗ mapping, multi-echo gradient-echo imaging was used (temporal resolution = 9 seconds). A step-like renal oxygenation challenge was applied involving sequential exposure to hyperoxia (100% O2 ), hypoxia (10% O2 + 90% N2 ), and hyperoxia (100% O2 ). In vivo experiments were performed in healthy rats (N = 10) and in rats with bilateral ischemia-reperfusion injury (N = 4). To assess the step response of renal oxygenation, a second-order exponential model was used (model parameters: amplitude [A], time delay [Δt], damping constant [D], and period of the oscillation [T]) for renal cortex, outer stripe of the outer medulla, inner stripe of the outer medulla, and inner medulla. RESULTS: The second-order exponential model permitted us to model the exponential T2∗ recovery and the superimposed T2∗ oscillation following renal oxygenation stimulus. The in vivo experiments revealed a difference in Douter medulla between healthy controls (D < 1, indicating oscillatory recovery) and ischemia-reperfusion injury (D > 1, reflecting aperiodic recovery). The increase in Douter medulla by a factor of 3.7 (outer stripe of the outer medulla) and 10.0 (inner stripe of the outer medulla) suggests that this parameter might be rather sensitive to (patho)physiological oxygenation changes. CONCLUSION: This study demonstrates the feasibility of monitoring the dynamic oxygenation response of renal tissues to a step-like oxygenation challenge using high-temporal-resolution T2∗ mapping. Our results suggest that the implemented system analysis approach may help to unlock questions regarding regulation of renal oxygenation, with the ultimate goal of providing imaging means for diagnostics and therapy of renal diseases.

Diffusion tensor imaging in renal artery stenosis: a preliminary report.

OBJECTIVE: To investigate the diffusion properties in the kidneys affected by renal artery stenosis (RAS) using diffusion tensor imaging (DTI). METHODS: In this prospective study, 35 patients with RAS and 15 patients without renal abnormalities were enrolled and examined using DTI. Cortical and medullary regions of interest (ROIs) were located to obtain the corresponding values of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA). The cortical and medullary ADC and FA were compared in the kidney affected by variable degrees of stenosis (RAS 50-75% and >75%) vs controls, using the one-way ANOVA and Student's t-test. The Spearman correlation test was used to correlate the mean ADC and FA values in the cortex and medulla with the estimate glomerular filtration rate (eGFR). RESULTS: For the controls, the ADC value was significantly (p = 0.03) higher in the cortex than in the medulla; the FA value was significantly (p = 0.001) higher in the medulla than in the cortex. Compared with the controls, a significant reduction in the cortical ADC was present with a RAS of 50-75% and >75% (p = 0.001 and 0.041, respectively); a significant reduction in the medullary FA was verified only for RAS >75% (p = 0.023). The Spearman correlation test did not show a statistically significant correlation between the cortical and medullary ADC and FA, and the eGFR. CONCLUSION: The alterations of the diffusional parameters caused by RAS can be detected by DTI and could be useful in the diagnostic evaluation of these patients. ADVANCES IN KNOWLEDGE: 1. Magnetic resonance DTI could provide useful information about renal involvement in RAS.2. Magnetic resonance DTI allows non-invasive repeatable evaluation of the renal parenchyma, without contrast media.

Can distinction between the renal cortex and outer medulla on ultrasonography predict estimated glomerular filtration rate in canine chronic kidney diseases?

BACKGROUND: Quantitative evaluation of renal cortical echogenicity (RCE) has been tried and developed in human and veterinary medicine. OBJECTIVES: The objective of this study was to propose a method for evaluating RCE quantitatively and intuitively, and to determine associations between ultrasonographic renal structural distinction and estimated glomerular filtration rate (eGFR) in canine chronic kidney disease (CKD). METHODS: Data were collected on 63 dogs, including 27 with normal kidney function and 36 CKD patients. Symmetric dimethylarginine and creatinine concentrations were measured for calculating eGFR. RCE was evaluated as 3 grades on ultrasonography images according to the distinction between the renal cortex and outer medulla. The RCE grade of each kidney was measured. RESULTS: There was a significant difference in eGFR between the group normal and CKD (p < 0.001). As mean of RCE grades (the mean values of each right and left kidney's RCE grade) increases, the proportion of group CKD among the patients in each grade increases (p < 0.001). Also, severity of RCE (classified as "high" if any right or left kidney evaluated as RCE grade 3, "low" otherwise) and eGFR is good indicator for predicting group CKD (p < 0.001). CONCLUSIONS: The degree of distinction between the renal cortex and the outer medulla is closely related to renal function including eGFR and the RCE grade defined in this study can be used as a method of objectively evaluating RCE.

Application of diffusion tensor imaging and blood oxygenation level-dependent magnetic resonance imaging to assess bilateral renal function induced by Iohexol in rabbits.

BACKGROUND: Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) and diffusion tensor imaging (DTI) are useful methods for investigating the morphology and function of the kidneys, including revealing unilateral renal damage. Nevertheless, these techniques have not yet been applied for bilateral renal function. The aim of this study was to investigate whether the combination of DTI and BOLD could be used to examine different degrees of contrast-induced acute kidney injury (CI-AKI) in bilateral kidneys compared to standard methods such as serum creatinine (SCr) detection. METHODS: Forty-Two New Zealand white rabbits were divided into two groups: the experimental group and the control group. Physiological saline and iodine contrast agent (iohexol, 1.0 g iodine/kg, 1.0 ml/sec) were injected via the right renal artery. DTI and BOLD-MR data were acquired longitudinally at the baseline and 1, 24, 48, and 72 h after high-pressure syringe injection to measure the apparent diffusion coefficient (ADC), fractional anisotropy (FA) and relative transverse relaxation rate (R2*). After the MR scan at each time point, three rabbits in each group were sacrificed, and changes in SCr and hypoxia-inducible factor-1α (HIF-1α) were analyzed using histopathology and immunochemistry. RESULTS: Twenty-four hours after iohexol administration, the values of ADC and FA decreased significantly (P < 0.05), while R2* values increased (P < 0.05) in the renal cortex (CO), outer medulla (OM) and inner medulla (IM). Besides, significant negative correlations were observed among ADC, FA, and R2* in CO, OM, and IM (all P < 0.001, r = - 0.654-0.828). CONCLUSIONS: DTI and BOLD can simultaneously and non-invasively assess different degrees of CI-AKI in bilateral kidneys.

Small renal masses (≤ 4 cm): differentiation of oncocytoma from renal clear cell carcinoma using ratio of lesion to cortex attenuation and aorta-lesion attenuation difference (ALAD) on contrast-enhanced CT.

PURPOSE: We investigate the use of ratio of lesion to cortex (L/C) attenuation and aorta-lesion attenuation difference (ALAD) on multiphase contrast-enhanced CT to help distinguish oncocytoma from clear cell RCC in small renal masses (diameter < 4 cm). METHODS: We retrospectively identified 76 patients that undergo CT before surgery for a suspicious small renal mass between January 2014 and December 2018 with pathological diagnosis of 21 oncocytomas (ROs), 25 clear cell RCCs, 7 chromophobe RCCs, 7 papillary RCCs, 7 multilocular cystic RCCs, 7 angiomyolipomas and 2 leiomyomas. CT attenuation values were obtained for the tumor, the normal renal cortex and the aorta, placing a circular region of interest (ROI) in the same slice by two radiologists, independently. RESULTS: In the corticomedullary phase, ROs showed isodense enhancement to the renal cortex (ratio L/C 0.92 ± 0.12), while clear cell RCCs appeared hypodense to the renal cortex (ratio L/C 0.69 ± 0.20; p < 0.01) with an accuracy of 80% for diagnosing RO. In nephrographic phase, the ratio L/C attenuation was lower than the corticomedullary phase in ROs (0.78 ± 0.11) showing an early washout pattern, while the ratio L/C was similar to the corticomedullary phase in clear cell RCCs (0.69 ± 0.13; p = 0.025, with an accuracy of 65% for diagnosing RO). The ratio L/C attenuation showed considerable overlap between ROs and clear cell RCCs in the excretory phase (p = 0.27). Mean ALAD values in the nephrographic phase were 21.95 ± 16.24 for ROs and 36.96 ± 30.53 for clear cell RCCs (p = 0.049). CONCLUSION: The ratio L/C attenuation in corticomedullary phase may be useful to differentiate RO from clear cell RCC.

Role of Chemical Exchange Saturation Transfer and Magnetization Transfer MRI in Detecting Metabolic and Structural Changes of Renal Fibrosis in an Animal Model at 3T.

OBJECTIVE: To investigate the value of combined chemical exchange saturation transfer (CEST) and conventional magnetization transfer imaging (MT) in detecting metabolic and structural changes of renal fibrosis in rats with unilateral ureteral obstruction (UUO) at 3T MRI. MATERIALS AND METHODS: Thirty-five Sprague-Dawley rats underwent UUO surgery (n = 25) or sham surgery (n = 10). The obstructed and contralateral kidneys were evaluated on days 1, 3, 5, and 7 after surgery. After CEST and MT examinations, 18F-labeled fluoro-2-deoxyglucose positron emission tomography was performed to quantify glucose metabolism. Fibrosis was measured by histology and western blots. Correlations were compared between asymmetrical magnetization transfer ratio at 1.2 ppm (MTRasym(1.2ppm)) derived from CEST and maximum standard uptake value (SUVmax) and between magnetization transfer ratio (MTR) derived from MT and alpha-smooth muscle actin (α-SMA). RESULTS: On days 3 and 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those of contralateral kidneys (p < 0.05). On day 7, MTRasym(1.2ppm) and MTR of UUO renal cortex and medulla were significantly different from those of sham-operated kidneys (p < 0.05). The MTRasym(1.2ppm) of UUO renal medulla was fairly negatively correlated with SUVmax (r = -0.350, p = 0.021), whereas MTR of UUO renal medulla was strongly negatively correlated with α-SMA (r = -0.744, p < 0.001). CONCLUSION: CEST and MT could provide metabolic and structural information for comprehensive assessment of renal fibrosis in UUO rats in 3T MRI and may aid in clinical monitoring of renal fibrosis in patients with chronic kidney disease.