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.

Time-resolved mapping of myocardial stiffness using 2D multifrequency spiral MR elastography with and without external vibration.

Purpose: There is a clinical need for stiffness mapping of the heart; however, current cardiac magnetic resonance elastography (cMRE) has limited spatiotemporal resolution. Therefore, we developed 2D spiral multifrequency MRE of the human heart and conducted a study to analyze the consistency and reproducibility of motion-encoding and stiffness mapping with and without external vibration.

Methods: Eleven healthy volunteers were studied using single-slice gradient-echo spiral cMRE with cardiac triggering and encoding of harmonic shear wave fields at 70, 80, and 90 Hz frequency generated by either external drivers or endogenous heart motion.

Open-source cardiac magnetic resonance fingerprinting.

Purpose: Cardiac magnetic resonance fingerprinting (cMRF) is a powerful quantitative imaging technique that provides multi-parametric diagnostic information. Here, we introduce an open-source framework for cardiac MRF including open-source pulse sequences, image reconstruction, and parameter estimation tools that are needed for the processing of the data.

Methods: A 2D cMRF sequence with a variable-density spiral readout is implemented using the open-source and vendor-agnostic sequence format Pulseq.

Noninvasive assessment of portal pressure by combined measurement of volumetric strain and stiffness of in vivo human liver.

Liver metabolism depends on the mechanical interplay between the solid tissue matrix and blood vessels, making shear modulus and pressure important variables of hepatic homeostasis. While shear modulus can be quantified by magnetic resonance elastography (MRE), pressure is not available through noninvasive imaging. We propose combined determination of liver deformation and shear modulus using volumetric MRI and MRE for noninvasive portal pressure assessment.

Magnetic resonance elastography in a nutshell: Tomographic imaging of soft tissue viscoelasticity for detecting and staging disease with a focus on inflammation.

Magnetic resonance elastography (MRE) is an emerging clinical imaging modality for characterizing the viscoelastic properties of soft biological tissues. MRE shows great promise in the noninvasive diagnosis of various diseases, especially those associated with soft tissue changes involving the extracellular matrix, cell density, or fluid turnover including altered blood perfusion - all hallmarks of inflammation from early events to cancer development. This review covers the fundamental principles of measuring tissue viscoelasticity by MRE, which are based on the stimulation and encoding of shear waves and their conversion into parameter maps of mechanical properties by inverse problem solutions of the wave equation.

Multimodal assessment of brain stiffness variation in healthy subjects using magnetic resonance elastography and ultrasound time-harmonic elastography.

Magnetic resonance elastography (MRE) is a noninvasive brain stiffness mapping method. Ultrasound-based transtemporal time-harmonic elastography (THE) is emerging as a cost-effective, fast alternative that has potential applications for bedside monitoring of intracranial pressure. We aim to investigate the accuracy of THE in comparison to MRE performed in the brain.