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Purpose: Hepatic magnetic resonance elastography (MRE) is currently a breath-hold imaging technique. Patients with chronic liver disease can have comorbidities that limit their ability to breath-hold (BH) for the required acquisition time. Our aim was to evaluate whether stiffness measurements obtained from a navigator-triggered MRE acquisition are comparable to standard expiratory breath-hold, inspiratory breath-hold or free-breathing in healthy participants., Materials and Methods: Twelve healthy participants were imaged using the four methods on a clinical 1.5T MR system equipped with a product MRE system. Mean liver stiffness, and measurable area of stiffness (with a confidence threshold >95%) were compared between sequences using the concordance correlation coefficient. Repeatability of each sequence between two acquisitions was also assessed., Results: The standard BH expiratory technique had high concordance with the navigated technique (r=0.716), and low concordance with the BH inspiration (r=0.165) and free-breathing (r=0.105) techniques. The navigator-triggered technique showed no statistical difference in measurable area of liver or in repeatability compared with the standard expiratory acquisition (p=0.997 and p=0.407 respectively). The free-breathing technique produced less measurable liver area and was less repeatable than the alternative techniques. The increase in acquisition time for navigator techniques was 3min 6s compared to standard expiratory breath-hold., Conclusion: Navigator-based hepatic MRE measurements are comparable to the reference standard expiratory breath-hold acquisition in healthy participants., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: We conducted an individual participant data (IPD) pooled analysis on diagnostic accuracy of MRE to detect fibrosis stage in patients with non-alcoholic fatty liver disease (NAFLD)., Methods: Through a systematic literature search, we identified studies of MRE (at 60-62.5 Hz) for staging fibrosis in patients with NAFLD, using liver biopsy as gold standard, and contacted study authors for IPD. Through pooled analysis, we calculated the cluster-adjusted AUROC, sensitivity and specificity of MRE for any (≥stage 1), significant (≥stage 2) and advanced (≥stage 3) fibrosis and cirrhosis (stage 4)., Results: We included nine studies with 232 patients with NAFLD (mean age, 51 ± 13 years; 37.5% males; mean BMI, 33.5 ± 6.7 kg/m(2); interval between MRE and biopsy <1 year, 98.3%). Fibrosis stage distribution (stage 0/1/2/3/4) was 33.6, 32.3, 10.8, 12.9 and 10.4%, respectively. Mean AUROC (and 95% CIs) for diagnosis of any, significant or advanced fibrosis and cirrhosis was 0.86 (0.82-0.90), 0.87 (0.82-0.93), 0.90 (0.84-0.94) and 0.91 (0.76-0.95), respectively. Similar diagnostic performance was observed in stratified analysis based on sex, obesity and degree of inflammation., Conclusions: MRE has high diagnostic accuracy for detection of fibrosis in NAFLD, independent of BMI and degree of inflammation., Key Points: • MRE has high diagnostic accuracy for detection of fibrosis in NAFLD. • BMI does not significantly affect accuracy of MRE in NAFLD. • Inflammation had no significant influence on MRE performance in NAFLD for fibrosis., Competing Interests: This research has been reviewed by the Mayo Clinic Conflict of Interest Review Board and is being conducted in compliance with Mayo Clinic Conflict of Interest policies. None of the other authors have any disclosures.

Background and Aims: We conducted an individual participant data (IPD) pooled analysis on the diagnostic accuracy of magnetic resonance elastography (MRE) to detect fibrosis stage in liver transplant recipients., Material and Methods: Through a systematic literature search, we identified studies on diagnostic performance of MRE for staging liver fibrosis, using liver biopsy as gold standard. We contacted study authors for published and unpublished IPD on age, sex, body mass index, liver stiffness, fibrosis stage, degree of inflammation and interval between MRE and biopsy; from these we limited analysis to patients who had undergone liver transplantation. Through pooled analysis using nonparametric two-stage receiver-operating curve (ROC) regression models, we calculated the cluster-adjusted AUROC, sensitivity and specificity of MRE for any (≥ stage 1), significant (≥ stage 2) and advanced fibrosis (≥ stage 3) and cirrhosis (stage 4)., Results: We included 6 cohorts (4 published and 2 unpublished series) reporting on 141 liver transplant recipients (mean age, 57 years; 75.2% male; mean BMI, 27.1 kg/m2). Fibrosis stage distribution stage 0, 1, 2, 3, or 4, was 37.6%, 23.4%, 24.8%, 12% and 2.2%, respectively. Mean AUROC values (and 95% confidence intervals) for diagnosis of any (≥ stage 1), significant (≥ stage 2), or advanced fibrosis (≥ stage 3) and cirrhosis were 0.73 (0.66-0.81), 0.69 (0.62-0.74), 0.83 (0.61-0.88) and 0.96 (0.93-0.98), respectively. Similar diagnostic performance was observed in stratified analysis based on sex, obesity and inflammation grade., Conclusions: In conclusion, MRE has high diagnostic accuracy for detection of advanced fibrosis and cirrhosis in liver transplant recipients, independent of BMI and degree of inflammation., Competing Interests: This research has been reviewed by the Mayo Clinic Conflict of Interest Review Board and is being conducted in compliance with Mayo Clinic Conflict of Interest policies.

Objective: Hepatorenal syndrome (HRS) is the most lethal cause of renal impairment in cirrhosis. Magnetic resonance elastography (MRE) is a diagnostic test that characterises tissues based on their biomechanical properties. The aim of this study was to assess the feasibility of MRE for detecting HRS in cirrhotic patients., Methods: A prospective diagnostic investigation was performed. Renal MRE was performed on 21 hospitalised patients with cirrhosis and ascites. Six patients had HRS, one patient had non-HRS renal impairment, and 14 patients had normal renal function. The MRE-measured renal stiffness was compared against the clinical diagnosis as determined by clinical review alongside laboratory and radiologic results., Results: The MRE-measured renal stiffness was significantly lower in patients with HRS (median stiffness of 3.30 kPa at 90 Hz and 2.62 kPa at 60 Hz) compared with patients with normal renal function (median stiffness of 5.08 kPa at 90 Hz and 3.41 kPa at 60 Hz) (P ≤ 0.014). For the detection of HRS, MRE had an area under the receiver operating characteristic curve of 0.94 at 90 Hz and 0.89 at 60 Hz. MRE had excellent inter-rater agreement, as assessed by Bland-Altman and intraclass correlation coefficient (> 0.9)., Conclusion: MRE shows potential in the detection of HRS., Key Points: • Magnetic resonance elastography (MRE) shows promise in the detection of hepatorenal syndrome. • MRE has the potential to track renal disease in a clinical population. • MRE is a reliable diagnostic test with excellent inter-rater agreement.

Background: To evaluate the reliability of MRE using a spin-echo echo-planar imaging (SE-EPI) renal MRE technique in healthy volunteers., Methods: Institutional review board approved prospective study in which all participants provided written informed consent. Sixteen healthy volunteers comprising seven males and nine females with a median age of 35 years (age range: 23 to 59 years) were included. Coronal 90 Hz and 60 Hz MRE acquisitions were performed twice within a 30-min interval between examinations. Renal MRE reliability was assessed by (i) test-retest repeatability, and (ii) inter-rater agreement between two independent readers. The MRE-measured averaged renal stiffness values were evaluated using: intraclass correlation coefficient (ICC), Bland-Altman and the within-subject coefficient of variation (COV)., Results: For test-retest repeatability, Bland-Altman showed a mean stiffness difference between examinations of 0.07 kPa (95% limits of agreement: -1.41, 1.54) at 90 Hz and 0.01 kPa (95% limits of agreement: -0.51, 0.53) at 60 Hz. Coefficient of repeatability was 1.47 kPa and 0.52 kPa at 90 Hz and 60 Hz, respectively. The within-subject COV was 13.6% and 7.7% at 90 Hz and 60 Hz, respectively. ICC values were 0.922 and 0.907 for test-retest repeatability and 0.998 and 0.989 for inter-rater agreement, respectively (P < 0.001)., Conclusion: SE-EPI renal MRE is a reliable technique., (© 2014 Wiley Periodicals, Inc.)

Background & Aims: Magnetic resonance elastography (MRE) is a noninvasive tool for staging liver fibrosis. We conducted a meta-analysis of individual participant data collected from published studies to assess the diagnostic accuracy of MRE for staging liver fibrosis in patients with chronic liver diseases (CLD)., Methods: Through a systematic literature search of multiple databases (2003-2013), we identified studies on diagnostic performance of MRE for staging liver fibrosis in patients with CLD with native anatomy, using liver biopsy as the standard. We contacted study authors to collect data on each participant's age, sex, body mass index (BMI), liver stiffness (measured by MRE), fibrosis stage, staging system used, degree of inflammation, etiology of CLD, and interval between MRE and biopsy. Through a pooled analysis, we calculated cluster-adjusted area under the receiver-operating curve, sensitivity, and specificity of MRE for any fibrosis (≥stage 1), significant fibrosis (≥stage 2), advanced fibrosis (≥stage 3), and cirrhosis (stage 4)., Results: We analyzed data from 12 retrospective studies, comprising 697 patients (mean age, 55 ± 13 y; 59.4% male; mean BMI, 26.9 ± 6.7 kg/m(2); 92.1% with <1 year interval between MRE and biopsy; and 47.1% with hepatitis C). Overall, 19.5%, 19.4%, 15.5%, 15.9%, and 29.7% patients had stage 0, 1, 2, 3, and 4 fibrosis, respectively. The mean area under the receiver-operating curve values (and 95% confidence intervals) for the diagnosis of any (≥stage 1), significant (≥stage 2), advanced fibrosis (≥stage 3), and cirrhosis, were as follows: 0.84 (0.76-0.92), 0.88 (0.84-0.91), 0.93 (0.90-0.95), and 0.92 (0.90-0.94), respectively. A similar diagnostic performance was observed in stratified analysis based on sex, obesity, and etiology of CLD. The overall rate of failure of MRE was 4.3%., Conclusions: Based on a pooled analysis of data from individual participants, MRE has a high accuracy for the diagnosis of significant or advanced fibrosis and cirrhosis, independent of BMI and etiology of CLD. Prospective studies are warranted to better understand the diagnostic performance of MRE., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Liver fibrosis is a common feature of many chronic liver diseases, and can ultimately progress to cirrhosis. Conventional imaging is insensitive to liver fibrosis, necessitating a liver biopsy for diagnosis and monitoring of progression. However, liver biopsy risks complications, and is an imperfect gold standard in view of sampling error and intraobserver or interobserver variation. Magnetic resonance elastography (MRE) is a noninvasive method for assessing the mechanical properties of tissues and is gaining credence as a method of assessment for hepatic fibrosis. The aim of this review is to describe how MRE is performed, to review the present literature on the subject, to compare MRE with other noninvasive techniques used to assess for liver fibrosis, and to highlight areas of future research., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objectives: Conventional imaging techniques are insensitive to liver fibrosis. This study assesses the diagnostic accuracy of MR elastography (MRE) stiffness values and the ratio of phosphomonoesters (PME)/phosphodiesters (PDE) measured using (31)P spectroscopy against histological fibrosis staging., Methods: The local research ethics committee approved this prospective, blinded study. A total of 77 consecutive patients (55 male, aged 49 ± 11.5 years) with a clinical suspicion of liver fibrosis underwent an MR examination with a liver biopsy later the same day. Patients underwent MRE and (31)P spectroscopy on a 1.5 T whole body system. The liver biopsies were staged using an Ishak score for chronic hepatitis or a modified NAS fibrosis score for fatty liver disease., Results: MRE increased with and was positively associated with fibrosis stage (Spearman's rank = 0.622, P < 0.001). PME/PDE was not associated with fibrosis stage (Spearman's rank = -0.041, p = 0.741). Area under receiver operating curves for MRE stiffness values were high (range 0.75-0.97). The diagnostic utility of PME/PDE was no better than chance (range 0.44-0.58)., Conclusions: MRE-estimated liver stiffness increases with fibrosis stage and is able to dichotomise fibrosis stage groupings. We did not find a relationship between (31)P MR spectroscopy and fibrosis stage., Key Points: Magnetic resonance elastography (MRE) and MR spectroscopy can both assess the liver. MRE is superior to ( 31 ) P MR spectroscopy in staging hepatic fibrosis. MRE is able to dichotomise liver fibrosis stage groupings. Gradient-echo MRE may be problematic in genetic haemochromatosis.

Aim: To demonstrate the feasibility of obtaining liver stiffness measurements with magnetic resonance elastography (MRE) at 3T in normal healthy volunteers using the same technique that has been successfully applied at 1.5 T., Methods and Materials: The study was approved by the local ethics committee and written informed consent was obtained from all volunteers. Eleven volunteers (mean age 35 ± 9 years) with no history of gastrointestinal, hepatobiliary, or cardiovascular disease were recruited. The magnetic resonance imaging (MRI) protocol included a gradient echo-based MRE sequence using a 60 Hz pneumatic excitation. The MRE images were processed using a local frequency estimation inversion algorithm to provide quantitative stiffness maps. Adequate image quality was assessed subjectively by demonstrating the presence of visible propagating waves within the liver parenchyma underlying the driver location. Liver stiffness values were obtained using manually placed regions of interest (ROI) outlining the liver margins on the gradient echo wave images, which were then mapped onto the corresponding stiffness image. The mean stiffness values from two adjacent sections were recorded., Results: Eleven volunteers underwent MRE. The quality of the MRE images was adequate in all the volunteers. The mean liver stiffness for the group was 2.3 ± 0.38 kPa (ranging from 1.7-2.8 kPa)., Conclusions: This preliminary work using MRE at 3T in healthy volunteers demonstrates the feasibility of liver stiffness evaluation at 3T without modification of the approach used at 1.5 T. Adequate image quality and normal MRE values were obtained in all volunteers. The obtained stiffness values were in the range of those reported for healthy volunteers in previous studies at 1.5 T. There was good interobserver reproducibility in the stiffness measurements., (Copyright © 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objective: The purpose of this article is to establish the range of normal splenic stiffness in healthy volunteers using MR elastography (MRE) and to investigate any correlation with physiologic parameters and driver position., Subjects and Methods: Sixteen volunteers (mean [+/- SD] age, 37 +/- 9 years) with no history of gastrointestinal, hepatobiliary, or cardiovascular disease were recruited. The MRI protocol included T2-weighted axial and gradient-echo MRE sequences using steady-state 60-Hz excitation. Two MRE acquisitions were performed, one with the driver placed on the right side of the abdomen and the other with the driver placed on the left side. Volunteers' body mass index (BMI), arterial mean blood pressure, age, spleen volume, and liver stiffness were also determined. Two radiologists independently measured the spleen stiffness on the MRE inversion images. The correlations between spleen stiffness and BMI, arterial mean blood pressure, age, spleen volume, and liver stiffness were quantified., Results: Sixteen volunteers underwent MRE. With the driver placed on the right side of the abdomen, the mean splenic stiffness was 3,565 +/- 586 Pa (range, 2,353-4,442 Pa); with the driver on the left side of the abdomen, the mean splenic stiffness was significantly (p < 0.004) different (4,255 +/- 625 Pa; range, 3,194-5,581 Pa). No significant correlation was found between spleen stiffness and BMI, arterial mean blood pressure, age, spleen volume, and liver stiffness (all p > 0.05), Conclusion: These preliminary results in a small number of healthy volunteers show that spleen stiffness is not significantly correlated with BMI, arterial mean blood pressure, spleen volume, or liver stiffness. A significant difference was observed using different driver positions.