Technical Recommendation on Multi-Driver Multifrequency MR Elastography for Tomographic Mapping of Abdominal Stiffness With a Focus on the Pancreas and Pancreatic Ductal Adenocarcinoma.

Objectives: MR elastography (MRE) offers valuable mechanical tissue characterization for clinical diagnosis. However, conventional single-driver, single-frequency MRE systems are often limited by insufficient coverage of deep-seated organs like the pancreas. This study investigates whether multiplex MRE using multiple drivers and vibration frequencies can overcome these limitations.

Ultrasound hepatorenal index for the diagnosis of steatosis in patients with type 2 diabetes: a prospective validation study.

Objectives: To evaluate the performance of the ultrasound hepatorenal index (US-HRI) for the diagnosis of hepatic steatosis in patients with type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD), using MRI proton density fat fraction (MRI-PDFF) as reference.

Materials And Methods: This two-center prospective study included 129 and 263 patients in the training and validation cohorts, respectively, between 2019 and 2022. Hepatic steatosis was classified according to MRI-PDFF as S0 (≤ 6.

Prospective head-to-head comparison of non-invasive scores for diagnosis of fibrotic MASH in patients with type 2 diabetes.

Background & Aims: Non-invasive scores have been proposed to identify patients with fibrotic, metabolic dysfunction-associated steatohepatitis (MASH), who are at the highest risk of progression to complications of cirrhosis and may benefit from pharmacologic treatments. However, data in patients with type 2 diabetes (T2DM) are lacking. The aim of this multicenter prospective study was to perform a head-to-head comparison of FAST (FibroScan-aspartate aminotransferase [AST]), MAST (MRI-AST), MEFIB (magnetic resonance elastography [MRE] plus FIB-4), and FNI (fibrotic NASH index) for detecting fibrotic MASH in patients with T2DM.

Prospective Comparison of Attenuation Imaging and Controlled Attenuation Parameter for Liver Steatosis Diagnosis in Patients With Nonalcoholic Fatty Liver Disease and Type 2 Diabetes.

Background & Aims: Similarly to the controlled attenuation parameter (CAP), the ultrasound-based attenuation imaging (ATI) can quantify hepatic steatosis. We prospectively compared the performance of ATI and CAP for the diagnosis of hepatic steatosis in patients with type 2 diabetes and nonalcoholic fatty liver disease using histology and magnetic resonance imaging-proton density fat fraction (MRI-PDFF) as references.

Methods: Patients underwent ATI and CAP measurement, MRI, and biopsy on the same day.

Hepatocellular carcinoma in patients with non-alcoholic fatty liver disease is associated with heterogeneous pattern of fat infiltration in skeletal muscles.

Objectives: To evaluate the association between fat infiltration in skeletal muscles (myosteatosis) and hepatocellular carcinoma (HCC) in patients with non-alcoholic fatty liver disease (NAFLD).

Methods: In a cross-sectional cohort of 72 histologically proven NAFLD patients (n = 38 with non-alcoholic steatohepatitis; NASH), among which 20 had HCC diagnosed on biopsy, we used proton density fat fraction (PDFF) at MRI to evaluate myosteatosis in skeletal muscles (mean fat fraction and first order radiomic-based pattern) at the third lumbar level, namely in erector spinae (ES), quadratus lumborum (QL), psoas, oblique, and rectus muscles.

Results: PDFF was 70% higher in patients with HCC when compared to those without HCC (9.

Visco-Elastic Parameters at Three-Dimensional MR Elastography for Diagnosing Non-Alcoholic Steatohepatitis and Substantial Fibrosis in Mice.

Background: Nonalcoholic fatty liver disease (NAFLD) is increasing worldwide and is a growing cause of liver cirrhosis and cancer. The performance of the magnetic resonance elastography (MRE) visco-elastic parameters in diagnosing progressive forms of NAFLD, including nonalcoholic steatohepatitis (NASH) and substantial fibrosis (F ≥ 2), needs to be clarified.

Purpose: To assess the value of three-dimensional MRE visco-elastic parameters as markers of NASH and substantial fibrosis in mice with NAFLD.

Comparative Analysis of a Locally Resampling MR Elastography Reconstruction Algorithm in Liver Fibrosis.

Background: In magnetic resonance elastography (MRE), the precision of the observed mechanical depends on the ratio between mechanical wavelength and spatial resolution. Since the mechanical wavelength may vary with actuation frequency, between patients and depending on position, a unique spatial resolution may not always generate an optimal ratio for multifrequency acquisitions, in patients with varying degrees of disease or in mechanically heterogeneous organs.

Purpose: To describe an MRE reconstruction algorithm that adjusts the ratio between shear wavelength and pixel size, by locally resampling the matrix of shear displacement, and to assess its performance relative to existing reconstructions in different use cases.

Magnetic resonance elastography with guided pressure waves.

Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain.

Prospective comparison of transient elastography, MRI and serum scores for grading steatosis and detecting non-alcoholic steatohepatitis in bariatric surgery candidates.

Background & Aims: Tools for the non-invasive diagnosis of non-alcoholic steatohepatitis (NASH) in morbidly obese patients with suspected non-alcoholic fatty liver disease (NAFLD) are an unmet clinical need. We prospectively compared the performance of transient elastography, MRI, and 3 serum scores for the diagnosis of NAFLD, grading of steatosis and detection of NASH in bariatric surgery candidates.

Methods: Of 186 patients screened, 152 underwent liver biopsy, which was used as a reference for NAFLD (steatosis [S]>5%), steatosis grading and NASH diagnosis.

Necro-inflammatory activity grading in chronic viral hepatitis with three-dimensional multifrequency MR elastography.

The purpose of this study was to assess the diagnostic value of multifrequency MR elastography for grading necro-inflammation in the liver. Fifty participants with chronic hepatitis B or C were recruited for this institutional review board-approved study. Their liver was examined with multifrequency MR elastography.

Multifrequency magnetic resonance elastography for elasticity quantitation and optimal tissue discrimination: A two-platform liver fibrosis mimicking phantom study.

In the framework of algebraic inversion, magnetic resonance elastography (MRE) repeatability, reproducibility and robustness were evaluated on extracted shear velocities (or elastic moduli). The same excitation system was implemented at two sites equipped with clinical MR scanners of 1.5 and 3 T.

Tumor Solid Stress: Assessment with MR Elastography under Compression of Patient-Derived Hepatocellular Carcinomas and Cholangiocarcinomas Xenografted in Mice.

Malignant tumors have abnormal biomechanical characteristics, including high viscoelasticity, solid stress, and interstitial fluid pressure. Magnetic resonance (MR) elastography is increasingly used to non-invasively assess tissue viscoelasticity. However, solid stress and interstitial fluid pressure measurements are performed with invasive methods.

Analysis Protocols for MRI Mapping of Renal T.

The computation of T maps from MR datasets represents an important step toward the precise characterization of kidney disease models in small animals. Here the main strategies to analyze renal T mapping datasets derived from small rodents are presented. Suggestions are provided with respect to essential software requirements, and advice is provided as to how dataset completeness and quality may be evaluated.

Experimental Protocols for MRI Mapping of Renal T.

The water proton longitudinal relaxation time, T, is a common and useful MR parameter in nephrology research. Here we provide three step-by-step T-mapping protocols suitable for different types of nephrology research. Firstly, we provide a single-slice 2D saturation recovery protocol suitable for studies of global pathology, where whole-kidney coverage is unnecessary.

MRI Mapping of Renal T: Basic Concept.

In renal MRI, measurement of the T relaxation time of water molecules may provide a valuable biomarker for a variety of pathological conditions. Due to its sensitivity to the tissue microenvironment, T has gained substantial interest for noninvasive imaging of renal pathology, including inflammation and fibrosis. In this chapter, we will discuss the basic concept of T mapping and different T measurement techniques and we will provide an overview of emerging preclinical applications of T for imaging of kidney disease.

Quantification of hepatic steatosis with ultrasound: promising role of attenuation imaging coefficient in a biopsy-proven cohort.

Objectives: To prospectively assess the role of the US attenuation imaging coefficient (AC) for the diagnosis and quantification of hepatic steatosis.

Methods: One hundred and one patients underwent liver biopsy and US-AC measurement on the same day. Liver steatosis was graded according to biopsy as absent (S0 < 5%), mild (S1 5-33%), moderate (S2 33-66%), or severe (S3 > 66%); liver fibrosis was graded from F0 to F4.

Comparison of pulsed and oscillating gradient diffusion-weighted MRI for characterizing hepatocellular nodules in liver cirrhosis: ex vivo study in a rat model.

Background: In contrast to classical pulsed gradient diffusion-weighted MRI, oscillating gradient diffusion-weighted MR imaging (DWI) is sensitive to short distance diffusion changes at the intracellular level.

Purpose: To compare the diagnostic performance of pulsed and oscillating DWI for characterizing hepatocellular nodules in a rat model of hepatic cirrhosis.

Study Type: Prospective, experimental study.

Assessing Tumor Mechanics by MR Elastography at Different Strain Levels.

Background: Malignant tumors are associated with increased tissue rigidity, which can be an indicator of tumor progression. MR elastography (MRE) has the potential to study the variations of tumor mechanical properties. ex vivo studies have shown the ability of MRE to assess increase of mechanical properties; nevertheless, it has not yet been observed in vivo.

Endothelial fatty liver binding protein 4: a new targetable mediator in hepatocellular carcinoma related to metabolic syndrome.

Metabolic syndrome (MS) is becoming the leading risk factor for hepatocellular carcinoma (HCC). HCC development related to MS may occur in advanced or non-advanced liver fibrosis, suggesting specific molecular pathways. Among these pathways, basal inflammatory state and adipokines production are involved.

In vitro distinction between proinflammatory and antiinflammatory macrophages with gadolinium-liposomes and ultrasmall superparamagnetic iron oxide particles at 3.0T.

Background: Inflammation involves a heterogeneous macrophage population, for which there is no readily available MR assessment method.

Purpose: To assess the feasibility of distinguishing proinflammatory M1 and antiinflammatory M2 macrophages at MRI enhanced with gadolinium liposomes or ultrasmall superparamagnetic iron oxide particles.

Study Type: In vitro.

Obesity-induced pancreatopathy in rats is reversible after bariatric surgery.

Obesity is a risk factor for pancreatic diseases. Bariatric surgery is one of the most efficient treatments of morbid obesity. The aims were to assess pancreatic endocrine and exocrine lesions in obese rats, to analyze effects of bariatric surgery.

Quantitative MRI in murine radiation-induced rectocolitis: comparison with histopathological inflammation score.

Murine radiation-induced rectocolitis is considered to be a relevant animal model of gastrointestinal inflammation. The purpose of our study was to compare quantitative MRI and histopathological features in this gastrointestinal inflammation model. Radiation rectocolitis was induced by localized single-dose radiation (27 Gy) in Sprague-Dawley rats.

Magnetic resonance elastography of liver and spleen: Methods and applications.

The viscoelastic properties of the liver and spleen can be assessed with magnetic resonance elastography (MRE). Several actuators, MRI acquisition sequences and reconstruction algorithms have been proposed for this purpose. Reproducible results are obtained, especially when the examination is performed in standard conditions with the patient fasting.