Venous Excess Doppler Ultrasound for the Nephrologist: Pearls and Pitfalls.
Kidney medicine
The role of venous congestion in abnormal kidney function is being increasingly recognized. It is well known that unresolved congestion is associated with adverse kidney and overall outcomes in patients with heart failure. Similarly, any condition that leads to elevated central venous pressure, such as pulmonary hypertension, can result in impaired kidney perfusion by increasing its afterload. Point-of-care ultrasonography (POCUS) enables the clinician to objectively assess hemodynamics at the bedside and, thereby, guide patient management. Lung POCUS has received widespread attention in the recent past because of the relative ease of the technique, but it reflects only left heart pressures and not venous congestion. Although inferior vena cava POCUS is used to estimate right atrial pressure, its isolated use cannot demonstrate organ congestion. Moreover, it is associated with several technical and conceptual limitations. Recently, venous excess Doppler ultrasound has emerged as a tool to assess venous congestion at the organ level in real time. Severe flow abnormalities in hepatic, portal, and kidney parenchymal veins have shown to predict the risk of congestive kidney injury. In addition, it helps to objectively monitor the efficacy of decongestive therapy. In this review, we provide a brief overview of various components of venous excess Doppler ultrasound and share our perspective on incorporating this novel tool in nephrology practice.
10.1016/j.xkme.2022.100482
An overview of renal transplantation: current practice and use of ultrasound.
Irshad Abid,Ackerman Susan J,Campbell Amy S,Anis Munazza
Seminars in ultrasound, CT, and MR
Imaging has played a major role in monitoring the well-being of the renal graft. Ultrasound, in particular, has been extremely helpful for the detection of postoperative complications related to the transplant kidney. From an imaging perspective, the complications of renal transplantation can be categorized into vascular complications, complications related to the collecting systems (urological complications), perinephric fluid collections, and parenchymal complications. Additionally, there are some complications that may occur, secondary to a transplant renal biopsy. To be able to correctly identify the complications associated with renal transplants, one should have a comprehensive understanding of various aspects of the transplant procedure and be familiar with the normal or expected findings after a transplant. This article provides an overview of renal transplantation and discusses the use of various imaging modalities in its evaluation. The various complications associated with renal transplant as well as renal biopsy are elaborated in this article with special emphasis on the use of ultrasound.
10.1053/j.sult.2009.03.001
Left Renal Cortical Thickness Measured by Ultrasound Can Predict Early Progression of Chronic Kidney Disease.
Takata Tomoaki,Koda Masahiko,Sugihara Takaaki,Sugihara Shinobu,Okamoto Toshiaki,Miyoshi Kenichi,Hodotsuka Masanori,Fujise Yuki,Matono Tomomitsu,Okano Junichi,Hosho Keiko,Iyama Takuji,Fukui Takeaki,Fukuda Satoko,Munemura Chishio,Isomoto Hajime
Nephron
AIMS:The kidney becomes atrophic in advanced chronic kidney disease, and renal size and parenchymal volume correlate with renal function. However, alterations in renal parenchymal volume have not been adequately studied in terms of the renal cortex and medulla. We investigated the relationship between the changes in the renal cortex and medulla and renal function. METHODS:Renal ultrasound (US) parameters including renal length, parenchymal thickness, cortical thickness and medullary thickness were assessed in 176 subjects, who were categorized into 4 groups based on the estimated glomerular filtration rate (ml/min/1.73 m2): group 1, ≥ 90; group 2, ≥ 60 but < 90; group 3, ≥ 30 but < 60; and group 4, < 30. Renal US parameters in both kidneys were compared among the 4 groups. RESULTS:We found stepwise associations in renal length, cortical thickness and parenchymal thickness with decreased renal function. Medullary thickness showed no changes among groups 1-3. Multiple linear regression analysis including sex, age and renal US parameters showed that only renal length was an independent predictor of renal function. When analyzed in groups 1-3, cortical thickness was the strongest associated parameter. Lower cortical left/right ratio (left cortical thickness/right cortical thickness) showed a stepwise association with a decrease in renal function. CONCLUSION:Renal length and cortical thickness measured by US were correlated with renal function. In particular, left cortical thickness could help to detect early changes in renal function.
10.1159/000441957
Correlation of Ultrasonographic Parameters with Serum Creatinine and Estimated Glomerular Filtration Rate in Patients with Echogenic Kidneys.
Gupta Prashant Kumar,Kunwar Laxman,Bc Bom,Gupta Aarti
Journal of Nepal Health Research Council
BACKGROUND:Ultrasonography is widely used to evaluate the kidney status. Serum creatinine and glomerular filtration rate assess the functional status of the kidney. This study tried to find the association between renal parameters in ultrasonography, serum creatinine and estimated glomerular filtration rate in patients with echogenic kidneys. METHODS:Study was done in 61 patients. Four sonographic renal parameters (renal echogenicity grade, renal length, cortical thickness, parenchymal thickness) were obtained from patients showing echogenic kidneys irrespective of cause during ultrasonography of abdomen. Glomerular filtration rate was calculated using Modified Diet in Renal Disease formula after obtaining patient's serum creatinine level. Sonographic renal parameters were compared with serum creatinine and estimated glomerular filtration rate using Pearson's correlation coefficient and one-way ANOVA tests. RESULTS:The study showed significant correlation of only renal echogenicity grade and parenchymal thickness with eGFR. However, all four sonographic renal parameters showed significant correlation with serum creatinine level. Renal echogenicity grading had strongest correlation with both serum creatinine (r=0.571, p=0.000) and estimated glomerular filtration rate (r= -0.349, p=0.006). Mean serum creatinine (in mg/dL) ± standard deviation was 1.9(±1.5), 4.0(±3.7), 5.8(±3.7), and 15.4(±5.3) for grade I, II, III, and IV echogenic kidneys respectively. Similarly, mean eGFR (in ml/min/1.73m2) ± standard deviation was 50.2(±22.9), 35.9(±40), 15.7(±13.4), and 3.4(±1.1) for Grade I, II, III, and IV echogenic kidneys respectively. CONCLUSIONS:Renal echogenicity is a better sonographic parameter that correlated well with both eGFR and serum creatinine. Renal ultrasound should be routinely used for early diagnosis, grading and monitoring of kidney disease.
10.33314/jnhrc.v18i3.2760
Ultrasonographic quantification of hepatic-renal echogenicity difference in hepatic steatosis diagnosis.
Wang Jing-Houng,Hung Chao-Hung,Kuo Fang-Ying,Eng Hock-Liew,Chen Chien-Hung,Lee Chun-Mo,Lu Sheng-Nan,Hu Tsung-Hui
Digestive diseases and sciences
BACKGROUND AND AIM:Ultrasound (US) is recommended for hepatic steatosis screening. The purpose of this study was to determine the usefulness of US hepatic-renal echo-intensity (HR) difference in the quantitative assessment of hepatic steatosis. METHODS:Consecutive patients undergoing liver biopsy were prospectively enrolled. Using US histogram technique, the mean gray level of hepatic parenchyma and right renal parenchyma at selected regions of interest were evaluated on the same day of biopsy. With steatosis assessed by histology as the reference, the diagnostic performances of HR difference in predicting the degree of steatosis was analyzed. The optimal cut-off level, diagnostic validity and post-test probability were assessed. RESULTS:A total of 175 patients were enrolled (M/F, 103/72; mean age, 48.6 ± 11.7). There were 64 (36.5 %), 42 (24 %), 29 (16.6 %), 12 (6.9 %) and 28 (16 %) patients with steatosis of <5, 5-9, 10-19, 20-29 and ≥ 30 %, respectively. Multivariate analysis showed HR difference correlated with the severity of steatosis (R (2) = 0.425, p < 0.001) with positive correlation between HR difference and the severity of steatosis (r = 0.60, p < 0.001). The diagnostic performances were 0.927, 0.890, 0.816 and 0.760 for steatosis ≥ 30, ≥ 20, ≥ 10 and ≥ 5 %, respectively. The cut-off is 7 for diagnosing steatosis ≥ 30 %, with a negative predictive value of 97.6 %. The cut-off is 4 in predicting steatosis ≥ 5 %, with a positive predictive value of 79 %. The prevalence of steatosis influenced the post-test probability. CONCLUSIONS:Quantitative assessment of HR difference with US histogram technique is useful in excluding moderate to severe hepatic steatosis.
10.1007/s10620-013-2769-8
Renal transplant elasticity ultrasound imaging: correlation between normalized strain and renal cortical fibrosis.
Gao Jing,Weitzel William,Rubin Jonathan M,Hamilton James,Lee Jun,Dadhania Darshana,Min Robert
Ultrasound in medicine & biology
After transplantation, over a widely variable time course, the cortex of the transplanted kidney becomes stiffer as interstitial fibrosis develops and renal function declines. Elasticity ultrasound imaging (EUI) has been used to assess biomechanical properties of tissue that change in hardness as a result of pathologic damage. We prospectively assessed the hardness of the renal cortex in renal transplant allograft patients using a normalized ultrasound strain procedure measuring quasi-static deformation, which was correlated with the grade of renal cortical fibrosis. To determine cortical strain, we used 2-D speckle-tracking software (EchoInsight, Epsilon Imaging, Ann Arbor, MI, USA) to perform offline analysis of stored ultrasound loops capturing deformation of renal cortex and its adjacent soft tissue produced by pressure applied using the scanning transducer. Normalized strain is defined as the mean developed strain in the renal cortex divided by the overall mean strain measured in the soft tissues from the abdominal wall to pelvic muscles. Using the Banff scoring criteria for renal cortical fibrosis as the gold standard, we classified 20 renal transplant allograft biopsy tissue samples into two groups: group 1 (n = 10) with mild (<25%) renal cortical fibrosis and group 2 (n = 10) with moderate (26%-50%) renal cortical fibrosis. An unpaired two-tailed t-test was used to determine the statistical difference in strains between patients with mild and those with moderate renal cortical fibrosis. Receiver operating characteristic curve analysis was performed to assess the accuracy of developed strain and normalized strain in predicting moderate renal cortical fibrosis. The reference strain did not significantly differ between the two groups (p = 0.10). However, the developed renal cortical strain in group 1 with mild fibrosis was higher than that in group 2 with moderate fibrosis (p = 0.025). The normalized strain in group 1 was also higher than that in group 2 (p = 0.0014). The areas under receiver operating characteristic curves for developed strain and normalized strain were 0.78 and 0.95, respectively. The optimal cutoff for distinguishing moderate renal cortical fibrosis was -0.08 for developed strain (sensitivity = 0.50, specificity = 1.0) and 2.5 for normalized strain (sensitivity = 0.80, specificity = 1.0). In summary, renal cortex strain is strongly correlated with grade of renal cortical fibrosis. Normalized strain is superior to developed strain in distinguishing moderate from mild renal cortical fibrosis. We conclude that free-hand real-time strain EUI may be useful in assessing the progression of cortical fibrosis in renal transplant allografts. Further prospective study using this method is warranted.
10.1016/j.ultrasmedbio.2013.04.007
[Clinical ultrasound in nephrology].
Der nephrologe
When used correctly, modern ultrasound diagnostics are helpful for the nephrologist especially in emergency situations on the ward, in dialysis and in the emergency admission to quickly make the correct diagnosis or as a diagnostic gatekeeper to initiate the correct next diagnostic and therapeutic steps in a time-saving manner. In addition to conventional B‑mode/gray scale sonography and Doppler sonography, new ultrasound transducers with higher spatial resolution and above all contrast agent sonography have significantly expanded the technical possibilities and help nephrologists and internists to answer diagnostic and clinical questions. This particularly applies to the kidneys, which up to now could only be clarified by means of contrast-enhanced computed tomography or magnetic resonance imaging. This will allow the nephrologist in 2021 to amalgamate the clinical symptoms, imaging results and pathophysiological knowledge in an ideal, time-saving manner for the benefit of the patient.
10.1007/s11560-021-00499-x
Quantitative parameters of contrast-enhanced ultrasonography for assessment of renal pathology: A preliminary study in chronic kidney disease.
Yang Wen-Qi,Mou Shan,Xu Yao,Xu Li,Li Feng-Hua,Li Hong-Li
Clinical hemorheology and microcirculation
OBJECTIVE:To assess the severity of renal pathology in patients with chronic kidney disease (CKD) using contrast-enhanced ultrasonography (US). METHODS:275 patients with CKD who were proven by renal biopsy and 30 healthy adults were examined using conventional US and contrast-enhanced US. Ultrasonic parameters included renal length, cortical thickness, rise time (RT), peak intensity (PI), area under the time-intensity curve (AUC), wash-in slope (WIS) and time to peak (TTP). Based on pathological scores, CKD patients were classified into mild, and moderate to severe CKD groups. The logistic regression analysis and receiver operating characteristic (ROC) curves were used. RESULTS:PI and AUC differed significantly among the controls, mild and moderate to severe CKD groups (P < 0.05). There was significant difference in PI among the different pathology types (P < 0.05). The multivariate logistic regression analysis showed that PI was associated independently with the severity of renal pathology in patients with CKD (P < 0.05). PI less than 13.87 dB had a certain diagnostic ability, and the sensitivity and specificity were 72.5% and 64.0%, respectively. CONCLUSIONS:Contrast-enhanced US may be useful for noninvasive assessment of the severity of renal pathology. PI may be potentially valuable for guiding therapy and follow-up in patients with CKD.
10.3233/CH-170303
Computer-assisted Sonographic Analysis of the Hepatorenal and Textural Features for the Diagnosis of the Fatty Liver.
Jeong Ji-Wook,Lee Sooyeul,Won Lee Jeong,Yoo Done-Sik,Kim Seunghwan
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
We investigated the B-mode ultrasound (US) images of abdomen by normalizing the gray level values of the liver with the representative gray levels (RGL's) of the liver parenchyma, renal cortex, subcutaneous fat, to quantify the fatty infiltration of the liver (FIL). The RGL's were compared with the clinical diagnosis of the FIL showing good correlation between them.
10.1109/IEMBS.2005.1617194
Ultrasonographic evaluation of the renal transplant.
Rodgers Shuchi K,Sereni Christopher P,Horrow Mindy M
Radiologic clinics of North America
Ultrasonography is an excellent tool for evaluation of the renal transplant in the immediate postoperative period and for long-term follow-up. In this article, normal imaging findings and complications of renal transplantations are described. Disease processes are divided into vascular, perinephric, urologic and collecting system, and parenchymal abnormalities. Attention is paid to the time of occurrence of each complication, classic imaging findings, and potential pitfalls.
10.1016/j.rcl.2014.07.009
[CME Sonography 99: Kidney Echo Changes].
Tuma Jan
Praxis
CME Sonography 99: Kidney Echo Changes 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.
10.1024/1661-8157/a003675
Quantitative Renal Echogenicity as a Tool for Diagnosis of Advanced Chronic Kidney Disease in Patients with Glomerulopathies and no Liver Disease.
Libório Alexandre B,de Oliveira Neves Fernanda Macedo,Torres de Melo Candice Bezerra,Leite Tacyano Tavares,de Almeida Leitão Renata
Kidney & blood pressure research
BACKGROUND/AIMS:Glomerulopathy patients are prone to developing transitory reduced glomerular filtration rate (GFR), which can be difficult to differentiate from irreversible chronic kidney disease (CKD). Renal ultrasound can be useful, but differently from renal length, quantitative renal echogenicity has not been formerly evaluated regarding its capacity to identify irreversible advanced CKD. METHODS:A prospective study was performed, where quantitative renal echogenicity was performed during renal biopsy in patients with suspected glomerular disease (n=197). Quantitative echogenicity was measured as the inverse of the ratio between the mean pixel densities of the renal cortex and adjacent liver using ScionImage software. Patients were followed during a six-months period to ascertain irreversible advanced CKD. Quantitative renal echogenicity and histopathology parameters discriminatory capacity were compared regarding their capacity to detect advanced and irreversible CKD - estimated GFR less than 30mL/min/1.73m2 confirmed after a six-month follow-up. RESULTS:At renal biopsy, the mean eGFR was 53.9±33.6 mL/min/1.73m2 and 63 (32.0%) patients had an eGFR less than 30 mL/min/1.73m2. Mean kidney/liver echogenicity ratio was 1.06±0.19 and it was inversely correlated with eGFR at follow-up (r=-0.684, p<0.001). Multivariate analysis was performed to create a histopathology index that correctly identifies irreversible advanced CKD. Renal echogenicity discriminatory capacity to identify irreversible advanced CKD was 0.793 (0.719 -0.867), similar to the histopathology index. Elevated renal echogenicity with best discriminatory capacity was a kidney/liver ratio greater than 1.15. This cutoff had a predictive positive value of 92% in patients with eGFR less than 30mL/min/1.73m2. CONCLUSION:Quantitative renal echogenicity can be a useful tool in patients with glomerular disease and normal kidney size (>8cm) to identify those patients with irreversible advanced CKD.
10.1159/000484105
An Objective Computer-Assisted Measurement of Sonographic Renal Cortical Echogenicity: The Splenorenal Index.
Ultrasound quarterly
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.
10.1097/RUQ.0000000000000646