High-frequency shear wave MR elastography of parotid glands: custom driver design and preliminary results.

Parotid glands are one of the most common sites for salivary gland tumors. Conventional imaging techniques have limited usefulness in the quantitative assessment of the parotid glands, making it difficult to differentiate between healthy tissue and tumors, as well as between benign and malignant tumors. Magnetic resonance elastography (MRE) is a non-invasive technique that may potentially overcome these limitations.

Feasibility study of the application of magnetic resonance elastography (MRE) to measure oral posture related changes in stiffness of zygomaticus major muscle.

Purpose: Development of a technique for measuring the mechanical properties of zygomaticus major (ZM) may aid advances in clinical treatments for correcting abnormal oral posture. The objective of this work was to demonstrate the feasibility of measuring the stiffness of ZM using an MR elastography technique that incorporates a custom local driver and a phase-gradient (PG) inversion.

Methods: 2D MRE investigations were performed for 3 healthy subjects using a vibration frequency of 90 Hz to test the prediction that the stiffness of ZM would be greater in the mouth-open compared to the mouth-closed position.

Wavelet MRE: Imaging propagating broadband acoustic waves with wavelet-based motion-encoding gradients.

Purpose: To demonstrate a novel MR elastography (MRE) technique, termed here wavelet MRE. With this technique, broadband motion sensitivity is achievable. Moreover, the true tissue displacement can be reconstructed with a simple inverse transform.

Head-to-head comparison of magnetic resonance elastography-based liver stiffness, fat fraction, and T1 relaxation time in identifying at-risk NASH.

Background And Aims: The presence of at-risk NASH is associated with an increased risk of cirrhosis and complications. Therefore, noninvasive identification of at-risk NASH with an accurate biomarker is a critical need for pharmacologic therapy. We aim to explore the performance of several magnetic resonance (MR)-based imaging parameters in diagnosing at-risk NASH.

Abdominal MR elastography with multiple driver arrays: performance and repeatability.

Purpose: To evaluate the performance and repeatability assessing liver, spleen, and kidney stiffness with magnetic resonance elastography (MRE), using arrays of pneumatic passive drivers.

Methods: An array of four flexible, pneumatically activated passive drivers for abdominal MRE were developed and tested in this study. Multiple MRE acquisitions were performed prospectively in a series of eleven volunteers, with activation of all combinations of the four drivers, individually and simultaneously.

Evaluation of a PEGylated Fibroblast Growth Factor 21 Variant Using Novel Preclinical Magnetic Resonance Imaging and Magnetic Resonance Elastography in a Mouse Model of Nonalcoholic Steatohepatitis.

Background: Treatments for nonalcoholic steatohepatitis (NASH) are urgently needed. Hepatic fat fraction and shear stiffness quantified by magnetic resonance imaging (MRI-HFF) and magnetic resonance elastography (MRE-SS), respectively, are biomarkers for hepatic steatosis and fibrosis.

Purpose: This study assessed the longitudinal effects of fibroblast growth factor 21 variant (polyethylene glycol [PEG]-FGF21v) on MRI-HFF and MRE-SS in a NASH mouse model.

Magnetic resonance elastography of the prostate in patients with lower urinary tract symptoms: feasibility of the modified driver at high multi-frequencies.

Purpose: To demonstrate the feasibility and diagnostic value of high-frequency magnetic resonance elastography (MRE) for evaluation of prostatic disease in patients with lower urinary tract symptoms (LUTS).

Methods: 41 patients who underwent preoperative prostate MRI and MRE with a modified driver were enrolled retrospectively from May 2016 to September 2021. All were included in the assessment of MRE image quality, using a qualitative visual inspection and a quantitative confidence map.

Multiparametric magnetic resonance imaging/magnetic resonance elastography assesses progression and regression of steatosis, inflammation, and fibrosis in alcohol-associated liver disease.

Background: Magnetic resonance imaging (MRI) and MRI-based elastography (MRE) are the most promising noninvasive techniques in assessing liver diseases. The purpose of this study was to evaluate an advanced multiparametric imaging method for staging disease and assessing treatment response in realistic preclinical alcohol-associated liver disease (ALD).

Methods: We utilized four different preclinical mouse models in our study: Model 1-mice were fed a fast-food diet and fructose water for 48 weeks to induce nonalcoholic fatty liver disease; Model 2-mice were fed chronic-binge ethanol (EtOH) for 10 days or 8 weeks to induce liver steatosis/inflammation.

Tumor stiffness measured by 3D magnetic resonance elastography can help predict the aggressiveness of endometrial carcinoma: preliminary findings.

Background: Preoperative evaluation of aggressiveness, including tumor histological subtype, grade of differentiation, Federation International of Gynecology and Obstetrics (FIGO) stage, and depth of myometrial invasion, is significant for treatment planning and prognosis in endometrial carcinoma (EC). The purpose of this study was to evaluate whether three-dimensional (3D) magnetic resonance elastography (MRE) can help predict the aggressiveness of EC.

Methods: From August 2015 to January 2019, 82 consecutive patients with suspected uterine tumors underwent pelvic MRI and MRE scans, and 15 patients with confirmed EC after surgical resection were enrolled.

Fast 3D MR elastography of the whole brain using spiral staircase: Data acquisition, image reconstruction, and joint deblurring.

Purpose: To address the need for a method to acquire 3D data for MR elastography (MRE) of the whole brain with substantially improved spatial resolution, high SNR, and reduced acquisition time compared with conventional methods.

Methods: We combined a novel 3D spiral staircase data-acquisition method with a spoiled gradient-echo pulse sequence and MRE motion-encoding gradients (MEGs). The spiral-out acquisition permitted use of longer-duration motion-encoding gradients (ie, over two full oscillatory cycles) to enhance displacement SNR, while still maintaining a reasonably short TE for good phase-SNR.

Comparison of the diagnostic performance of 2D and 3D MR elastography in staging liver fibrosis.

Objectives: To compare the diagnostic performance and image quality of state-of-the-art 2D MR elastography (MRE) and 3D MRE in the basic application of liver fibrosis staging.

Methods: This retrospective study assessed data from 293 patients who underwent 2D and 3D MRE examinations. MRE image quality was assessed with a qualitative 2-point grading system by evaluating artifacts.

Magnetic resonance elastography biomarkers for detection of histologic alterations in nonalcoholic fatty liver disease in the absence of fibrosis.

Objectives: To investigate associations between histology and hepatic mechanical properties measured using multiparametric magnetic resonance elastography (MRE) in adults with known or suspected nonalcoholic fatty liver disease (NAFLD) without histologic fibrosis.

Methods: This was a retrospective analysis of 88 adults who underwent 3T MR exams including hepatic MRE and MR imaging to estimate proton density fat fraction (MRI-PDFF) within 180 days of liver biopsy. Associations between MRE mechanical properties (mean shear stiffness (|G*|) by 2D and 3D MRE, and storage modulus (G'), loss modulus (G″), wave attenuation (α), and damping ratio (ζ) by 3D MRE) and histologic, demographic and anthropometric data were assessed.

Evaluation of MR elastography for prediction of lymph node metastasis in prostate cancer.

Purpose: To assess the relationship between MRE stiffness of prostate cancer (PCa) and the extent of lymph node metastasis (LNM) in patients with PCa undergoing radical prostatectomy (RP) and extended pelvic lymph node dissection (ePLND).

Materials: The local institutional review board approved this retrospective study. We retrospectively analyzed 49 patients, who had undergone MRE, mpMRI and pelvic MRI on a 3.

Value of liver iron concentration in healthy volunteers assessed by MRI.

Iron overload is a relatively common clinical condition resulting from disorders such as hereditary hemochromatosis, thalassemia, sickle cell disease, and myelodysplasia that can lead to progressive fibrosis and eventually cirrhosis of the liver. Therefore, it is essential to recognize the disease process at the earliest stage. Liver biopsy is the reference test for the assessment of liver fibrosis.

Quantitative assessment of portal hypertension with bi-parametric dual-frequency hepatic MR elastography in mouse models.

Objectives: To determine the potential of bi-parametric dual-frequency hepatic MR elastography (MRE) for predicting portal pressure (PP) in mouse models of portal hypertension (PHTN) with the presence of varying hepatic fibrosis.

Methods: We studied 73 wild-type male mice, including 22 mice with hepatic congestion, 20 mice with cholestatic liver injury, and 31 age-matched sham mice. Hepatic shear stiffness (SS) and volumetric strain (VS) were calculated by 3D MRE acquired at 80 and 200 Hz.

TURBINE-MRE: A 3D hybrid radial-Cartesian EPI acquisition for MR elastography.

Purpose: To develop a novel magnetic resonance elastography (MRE) acquisition using a hybrid radial EPI readout scheme (TURBINE), and to demonstrate its feasibility to obtain wave images and stiffness maps in a phantom and in vivo brain.

Method: The proposed 3D TURBINE-MRE is based on a spoiled gradient-echo MRE sequence with the EPI readout radially rotating about the phase-encoding axis to sample a full 3D k-space. A polyvinyl chloride phantom and 6 volunteers were scanned on a compact 3T GE scanner with a 32-channel head coil at 80 Hz and 60 Hz external vibration, respectively.

Multiparametric Magnetic Resonance Elastography Improves the Detection of NASH Regression Following Bariatric Surgery.

Disease monitoring in nonalcoholic steatohepatitis (NASH) is limited by absence of noninvasive biomarkers of disease regression or progression. We aimed to examine the role of multiparametric three-dimensional magnetic resonance elastography (3D-MRE) and magnetic resonance imaging proton density fat fraction (MRI-PDFF) in the detection of NASH regression after interventions. This is a single-center prospective clinical trial of 40 patients who underwent bariatric surgery.

Imaging brain function with simultaneous BOLD and viscoelasticity contrast: fMRI/fMRE.

Magnetic resonance elastography (MRE) is emerging as a new tool for studying viscoelastic changes in the brain resulting from functional processes. Here, we demonstrate a novel time series method to generate robust functional magnetic resonance elastography (fMRE) activation maps in response to a visual task with a flashing checkerboard stimulus. Using a single-shot spin-echo (SS-SE) pulse sequence, the underlying raw images inherently contain blood-oxygen-level dependent (BOLD) contrast, allowing simultaneous generation of functional magnetic resonance imaging (fMRI) activation maps from the magnitude and functional magnetic resonance elastography (fMRE) maps from the phase.

Characterization of Cellular Sources and Circulating Levels of Extracellular Vesicles in a Dietary Murine Model of Nonalcoholic Steatohepatitis.

Circulating extracellular vesicles (EVs) are a novel and emerging biomarker for nonalcoholic steatohepatitis (NASH). It has been demonstrated that total circulating EVs and hepatocyte-derived EVs are elevated in male mice with diet-induced NASH. How hepatocyte-derived EVs change over time and other cellular sources of EVs in NASH have not been determined.

Normal range for MR elastography measured liver stiffness in children without liver disease.

Background: Magnetic resonance elastography (MRE) can determine the presence and stage of liver fibrosis. Data on normative MRE values, while reported in adults, are limited in children.

Purpose: To determine the distribution of MRE-measured liver stiffness in children without liver disease.

Influence of Age on Global and Regional Brain Stiffness in Young and Middle-Aged Adults.

Background: An understanding of potential age-related changes in brain stiffness and its regional variation is important for further clinical application of MR elastography.

Purpose: To investigate the effect of age on global and regional brain stiffness in young and middle-aged adults.

Study Type: Prospective.

Prediction of nonalcoholic fatty liver disease (NAFLD) activity score (NAS) with multiparametric hepatic magnetic resonance imaging and elastography.

Objectives: To investigate the use of MR elastography (MRE)-derived mechanical properties (shear stiffness (|G*|) and loss modulus (G″)) and MRI-derived fat fraction (FF) to predict the nonalcoholic fatty liver disease (NAFLD) activity score (NAS) in a NAFLD mouse model.

Methods: Eighty-nine male mice were studied, including 64 training and 25 independent testing animals. An MRI/MRE exam and histologic evaluation were performed.

The Role of Three-Dimensional Magnetic Resonance Elastography in the Diagnosis of Nonalcoholic Steatohepatitis in Obese Patients Undergoing Bariatric Surgery.

The lack of reliable, noninvasive methods to diagnose early nonalcoholic steatohepatitis (NASH) is a major unmet need. We aimed to determine the diagnostic accuracy of three-dimensional magnetic resonance elastography (3D-MRE), with shear stiffness measured at 60 Hz, damping ratio at 40 Hz, and magnetic resonance imaging proton density fat fraction (MRI-PDFF) in the detection of NASH in individuals undergoing bariatric surgery. Obese adults at risk for NASH were enrolled between 2015 and 2017 (prospective cohort, n = 88) and 2010 and 2013 (retrospective cohort, n = 87).