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.

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.

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.

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 assessment of the flow distribution in the branches of the external carotid by non-injected flow MRI.

Owing to the lack of databases of blood flow distributions in the external carotid branches, surgeons currently rely on per-operative imaging and on their experience to choose the recipient vessels for microsurgical facial reconstructions. But, thanks to three-dimensional phase contrast angiography (PCA) and kinematic CINE phase contrast (PC) sequences, MRI technologies have the potential to provide quantitative anatomical and hemodynamic information without injection of contrast agent. Having developed and optimized PC-MRI sequences for the small facial vessels, our objective was to investigate the haemodynamic and blood flow distribution in the external carotid branches.

Influence of principal component analysis acceleration factor on velocity measurement in 2D and 4D PC-MRI.

Objective: The objective of the study was to determine how to optimize 2D and 4D phase-contrast magnetic resonance imaging (PC-MRI) acquisitions to acquire flow velocities in millimetric vessels. In particular, we search for the best compromise between acquisition time and accuracy and assess the influence of the principal component analysis (PCA).

Materials And Methods: 2D and 4D PC-MRI measurements are conducted within two in vitro vessel phantoms: a Y-bifurcation phantom, the branches of which range from 2 to 5 mm in diameter, and a physiological subject-specific phantom of the carotid bifurcation.

3T non-injected phase-contrast MRI sequences for the mapping of the external carotid branches: In vivo radio-anatomical pilot study for feasibility analysis.

An essential stage in head and neck microsurgical reconstruction is the choice of recipient vessels. To make relevant choices, surgeons must rely on accurate imaging techniques. The objective of the study was to examine the feasibility of Phase-Contrast sequences to conduct the pre-operative tests without injection and provide precise radio-anatomical data over the entire vessel region.