Ultrasound Elastography of the Kidney

Increased renal cortical stiffness is associated with coronary artery disease severity in patients with acute coronary syndrome

Atherosclerosis is the primary etiological factor associated with acute coronary syndrome (ACS). Kidneys have a highly arterial vascular structure and are therefore commonly affected by atherosclerosis, including those affecting the coronary arteries. Renal shear wave elastography (SWE) is an ultrasonographic method, which provides reliable information regarding the condition of the renal parenchyma.We investigated the relationship between SWE findings and the severity of coronary atherosclerosis.We calculated the following: the renal cortical stiffness (rCS) evaluated via SWE, the renal resistive index, the renal pulsatility index, the acceleration time, and the mean Syntax score (SS). Patients with a mean SS <12 were categorized into a low-risk (LR) and those with a mean SS ≥12 were categorized into the high-risk (HR) group.Our study included 132 patients-76 in the LR and 56 in the HR group. Creatinine, high-sensitivity C-reactive protein (hs-CRP), and rCS were significantly higher, but the glomerular filtration rate (GFR) was significantly lower in the HR group. The Hs-CRP (odds ratio [OR] 1.220), GFR (OR 0.967), and rCS (OR 1.316) were observed to be independent predictors for the HR group. The cutoff value of rCS using receiver-operating characteristic curve analysis was 4.43 for the prediction of HR patients and showed 60.7% sensitivity and 57.9% specificity (area under the curve 0.642).SWE which shows renal parenchymal injury and atherosclerosis in renal vessels may give an idea about the severity of coronary atherosclerosis.

Renal Cortical Elastography: Normal Values and Variations

Introduction

Renal cortical elastography has shown conflicting but promising results in evaluation of chronic kidney disease and other renal disorders. The purpose of this study was to establish a normogram of renal cortical elasticity values and assess their variation between right and left kidney and their relation with age, gender, body mass index, renal dimensions and skin to cortex distance.

Methods

The study was a hospital based cross sectional study performed at Tribhuvan University Teaching Hospital, a tertiary care center in Kathmandu, Nepal. All individuals referred for Ultrasound from General Health Check up clinic were included in the study. Patient with abnormal ultrasound findings and abnormal renal function test were excluded from the study. Renal morphometry including length, cortical thickness, and skin to cortex distance were measured in B mode imaging and renal cortical elastography was measured with region of interest box of 1 × 0.5 cm. All analyses were done using Statistical Package for Social Sciences 20.0 soft ware.

Results

A total of 95 individuals who met the inclusion criteria were included in the study. The mean values of right and left renal cortical shear wave velocity were 1.49 ± 0.19 m/s and 1.54 ± 0.19 m/s respectively. Statistical significant difference was observed between the renal cortical shear wave velocity of right and left kidney. The renal shear wave velocity was seen to decrease with age, however the correlation was not statistically significant. No significant difference was also noted in renal shear wave velocity among various sex or Body mass index groups. Statistically significant negative correlation was noted between skin to cortex distance and renal cortical shear wave velocities. However no statistically significant correlation was noted between renal dimensions and renal cortical shear wave velocities.

Conclusions

The normal cortical elasticity values in terms of shear wave velocity of right and left kidney were established. Renal elasticity is independent of the age, gender, Body mass index and renal dimensions.

Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography

Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from the OCT signals, such as optical attenuation and speckle variance. Furthermore, OCT does not rely on ionizing radiation as with CT imaging. In addition to structural changes, the elasticity of the kidney can significantly change due to nephritis. In this work, OCT has been utilized to quantify the difference in tissue properties between healthy and nephritic murine kidneys. Although OCT imaging could identify the diseased tissue, its classification accuracy is clinically inadequate. By combining optical metrics with elasticity, the classification accuracy improves from 76% to 95%. These results show that OCT combined with OCE can be a powerful tool for identifying and classifying nephritis. Therefore, the OCT/OCE method could potentially be used as a minimally invasive tool for longitudinal studies during the progression and therapy of glomerulonephritis as well as complement and, perhaps, substitute highly invasive tissue biopsies. Elastic-wave propagation in mouse healthy and nephritic kidneys.

Progression after AKI: Understanding Maladaptive Repair Processes to Predict and Identify Therapeutic Treatments

Recent clinical studies indicate a strong link between AKI and progression of CKD. The increasing prevalence of AKI must compel the nephrology community to consider the long-term ramifications of this syndrome. Considerable gaps in knowledge exist regarding the connection between AKI and CKD. The 13th Acute Dialysis Quality Initiative meeting entitled "Therapeutic Targets of Human Acute Kidney Injury: Harmonizing Human and Experimental Animal Acute Kidney Injury" convened in April of 2014 and assigned a working group to focus on issues related to progression after AKI. This article provides a summary of the key conclusions and recommendations of the group, including an emphasis on terminology related to injury and repair processes for both clinical and preclinical studies, elucidation of pathophysiologic alterations of AKI, identification of potential treatment strategies, identification of patients predisposed to progression, and potential management strategies.

Utility of Real-Time Shear Wave Elastography in the Assessment of Testicular Torsion

Real-time shear-wave elastography (SWE) is a newly developed method which can obtain the stiffness of tissues and organs based on tracking of shear wave propagation through a structure. Several studies have demonstrated its potential in the differentiation between diseased and normal tissue in clinical practices, however the applicability to testicular disease has not been well elucidated. We investigated the feasibility and reproducibility of SWE in the detection of testicular torsion. This prospective study comprised 15 patients with complete testicular torsion. Results obtained from SWE along with conventional gray-scale and color Doppler sonography and post-operative pathology were compared. The results revealed that (i) the size of injured testis was increased and the twisted testis parenchyma was heterogeneous. The blood flow signals in injured testis were barely visible or absent; (ii) The Young’s modulus, including Emean, Emax, Emin and SD values in the border area of torsional testis were higher than those of normal testis (Emean, 78.07±9.01kPa vs 22.0±5.10kPa; Emax,94.07±6.53kPa vs 27.87±5.78kPa; Emin, 60.73±7.84 kPa vs 18.90±4.39kPa; SD, 7.67±0.60 kPa vs 2.30±0.36 kPa, [P<0.05]); The Emax and SD values in the central area of the torsional testis were higher than the corresponding area of the normal testis (Emax, 8.23±0.30 kPa vs 3.97±0.95kPa; SD, 1.5±0.26kPa vs 0.67±0.35kPa,[P<0.05]) and Emin values was lower than those of normal testicles(0.93±0.51kPa vs 1.6±0.36kPa; [P<0.05]); (iii) The Young's modulus measurement between two physicians showed good agreement. The pathological findings were accordance with SWE measurement. SWE is a non-invasive, convenient and high reproducible method and may serve as an important alternative tool in the diagnosis and monitoring the progression of the acute scrotums, in additional to conventional Doppler sonography.

Strain wave elastography for evaluation of renal parenchyma in chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is an important and costly health problem in developed countries and has a tendency to progress to end-stage renal disease regardless of the aetiology. This progress ends in interstitial fibrosis, which decreases the elasticity of tissue. Elastography is a developing technique to assess tissue elasticity. The aim of this study was to determine the difference of strain index (SI) value of renal parenchyma between patients with CKD and healthy individuals. In addition, SI differences of inter-stages were studied.

METHODS

Toshiba (Toshiba Medical Systems Corporation, Otawara, Japan) Aplio™ 500 ultrasound device and 3.5- to 5.0-MHz convex probe were used for the elastography examinations.

RESULTS

A total of 58 patients with CKD from nephrology and endocrinology clinics (30 males and 28 females; mean age, 56.14 ± 11.60 years) and 40 normal healthy individuals (19 males and 21 females; mean age, 51.70 ± 11.71 years) were included in this prospective study. The mean SI of normal healthy individuals and patients with CKD (regardless of stages) was 0.42 ± 0.30 and 1.81 ± 0.88, respectively (p < 0.001). SI values were not statistically significant among the CKD stages (except CKD Stages 1 and 3). The area under the receiver operating characteristic curve was 0.956 for SI. The optimal cut-off value for the prediction of CKD was 0.935 (sensitivity, 88% and specificity, 95%).

CONCLUSION

SI value of sonoelastography can be used to differentiate patients with CKD and healthy individuals. Sonoelastography is an acceptable technique to approach patients with CKD, but we have not shown that it can reliably differentiate different stages.

ADVANCES IN KNOWLEDGE

Determining a cut-off SI value between normal and diseased renal parenchyma can help in the diagnosis of CKD.