Trajectory correction enables free-running chemical shift encoded imaging for accurate cardiac proton-density fat fraction quantification at 3T.

Background: Metabolic diseases can negatively alter epicardial fat accumulation and composition, which can be probed using quantitative cardiac chemical shift encoded (CSE) cardiovascular magnetic resonance (CMR) by mapping proton-density fat fraction (PDFF). To obtain motion-resolved high-resolution PDFF maps, we proposed a free-running cardiac CSE-CMR framework at 3T. To employ faster bipolar readout gradients, a correction for gradient imperfections was added using the gradient impulse response function (GIRF) and evaluated on intermediate images and PDFF quantification.

3D Observation of Pelvic Organs with Dynamic MRI Segmentation: A Bridge Toward Patient-Specific Models.

Introduction And Hypothesis: Female pelvic organ prolapses are common, but their treatment is challenging. Notably, diagnosis and understanding of these troubles remain incomplete. Tridimensional observations of displacement and deformation of the pelvic organs during a strain could support a better understanding and help to develop comprehensive tools for preoperative planning.

Low-rank reconstruction for simultaneous double half-echo Na and undersampled Na multi-quantum coherences MRI.

Purpose: To develop a new sequence to simultaneously acquire Cartesian sodium (Na) MRI and accelerated Cartesian single (SQ) and triple quantum (TQ) sodium MRI of in vivo human brain at 7 T by leveraging two dedicated low-rank reconstruction frameworks.

Theory And Methods: The Double Half-Echo technique enables short echo time Cartesian Na MRI and acquires two k-space halves, reconstructed by a low-rank coupling constraint. Additionally, three-dimensional (3D) Na Multi-Quantum Coherences (MQC) MRI requires multi-echo sampling paired with phase-cycling, exhibiting a redundant multidimensional space.

How to use MRI in cardiac disease with diastolic dysfunction?

Left ventricular (LV) diastolic dysfunction (DD) is an initially asymptomatic condition that can progress to heart failure, either with preserved or reduced ejection fraction. As such, DD is a growing public health problem. Impaired relaxation, the first stage of DD, is associated with altered LV filling.

Mitigating slice cross-talk in multi-slice multi-echo spin echo T mapping.

Purpose: To investigate whether a T inter-slice variation could occur when a multi-slice multi-echo spin echo (MESE) sequence is used for image acquisition and to propose an enhanced method for reconstructing T maps that can effectively address and correct these variations.

Methods: Bloch simulations were performed accounting for the direct saturation effect to evaluate magnetization changes in multi-slice 2D MESE sequence. Experimental phantom scans were performed to validate these simulations.

Comparative review of algorithms and methods for chemical-shift-encoded quantitative fat-water imaging.

Purpose: To propose a standardized comparison between state-of-the-art open-source fat-water separation algorithms for proton density fat fraction (PDFF) and quantification using an open-source multi-language toolbox.

Methods: Eight recent open-source fat-water separation algorithms were compared in silico, in vitro, and in vivo. Multi-echo data were synthesized with varying fat-fractions, B off-resonance, SNR and TEs.

Improved reproducibility for myocardial ASL: Impact of physiological and acquisition parameters.

Purpose: To investigate and mitigate the influence of physiological and acquisition-related parameters on myocardial blood flow (MBF) measurements obtained with myocardial Arterial Spin Labeling (myoASL).

Methods: A Flow-sensitive Alternating Inversion Recovery (FAIR) myoASL sequence with bSSFP and spoiled GRE (spGRE) readout is investigated for MBF quantification. Bloch-equation simulations and phantom experiments were performed to evaluate how variations in acquisition flip angle (FA), acquisition matrix size (AMS), heart rate (HR) and blood relaxation time ( ) affect quantification of myoASL-MBF.

Four-dimensional reconstruction and characterization of bladder deformations.

Background And Objective: Pelvic floor disorders are prevalent diseases and patient care remains difficult as the dynamics of the pelvic floor remains poorly understood. So far, only 2D dynamic observations of straining exercises at excretion are available in the clinics and 3D mechanical defects of pelvic organs are not well studied. In this context, we propose a complete methodology for the 3D representation of non-reversible bladder deformations during exercises, combined with a 3D representation of the location of the highest strain areas on the organ surface.

Synthetic computed tomography generation for abdominal adaptive radiotherapy using low-field magnetic resonance imaging.

Background And Purpose: Magnetic Resonance guided Radiotherapy (MRgRT) still needs the acquisition of Computed Tomography (CT) images and co-registration between CT and Magnetic Resonance Imaging (MRI). The generation of synthetic CT (sCT) images from the MR data can overcome this limitation. In this study we aim to propose a Deep Learning (DL) based approach for sCT image generation for abdominal Radiotherapy using low field MR images.

Characterisation of a split gradient coil design induced systemic imaging artefact on 0.35 T MR-linac systems.

. The aim of this work was to highlight and characterize a systemic 'star-like' artefact inherent to the low field 0.35 T MRIdian MR-linac system, a magnetic resonance guided radiotherapy device.

Traction mechanical characterization of porcine mitral valve annulus.

The Mitral Annulus (MA) is an anisotropic, fibrous, flexible and dynamical structure. While MA dynamics are well documented, its passive mechanical properties remain poorly investigated to complete the design of adequate prostheses. Mechanical properties in traction on four sections of the MA (aortic, left, posterior and right segments) were assessed using a traction test system with a 30 N load cell and pulling jaws for sample fixation.

Dynamic-MRI quantification of abdominal wall motion and deformation during breathing and muscular contraction.

Background And Objective: Biomechanical assessment of the abdominal wall represents a major prerequisite for a better understanding of physiological and pathological situations such as hernia, post-delivery recovery, muscle dystrophy or sarcopenia. Such an assessment is challenging and requires muscular deformations quantification which have been very scarcely reported in vivo. In the present study, we intended to characterize abdominal wall deformations in passive and active conditions using dynamic MRI combined to a semiautomatic segmentation procedure.

Cardiac MRI Features and Prognostic Value in Immune Checkpoint Inhibitor-induced Myocarditis.

Background Cardiac MRI features are not well-defined in immune checkpoint inhibitor (ICI)-induced myocarditis (ICI-M), a severe complication of ICI therapy in patients with cancer. Purpose To analyze the cardiac MRI features of ICI-M and to explore their prognostic value in major adverse cardiovascular events (MACE). Materials and Methods In this retrospective study from May 2017 to January 2020, cardiac MRI findings (including late gadolinium enhancement [LGE], T1 and T2 mapping, and extracellular volume fraction [ECV] scores) of patients with ICI-M were compared with those of patients with cancer scheduled to receive ICI therapy (pre-ICI group) and patients with viral myocarditis.

Deep-Learning Segmentation of Epicardial Adipose Tissue Using Four-Chamber Cardiac Magnetic Resonance Imaging.

In magnetic resonance imaging (MRI), epicardial adipose tissue (EAT) overload remains often overlooked due to tedious manual contouring in images. Automated four-chamber EAT area quantification was proposed, leveraging deep-learning segmentation using multi-frame fully convolutional networks (FCN). The investigation involved 100 subjects-comprising healthy, obese, and diabetic patients-who underwent 3T cardiac cine MRI, optimized U-Net and FCN (noted FCNB) were trained on three consecutive cine frames for segmentation of central frame using dice loss.

Volumetric Na Single and Triple-Quantum Imaging at 7T: 3D-CRISTINA.

Purpose: To measure multi-quantum coherence (MQC) Na signals for noninvasive cell physiological information in the whole-brain, the 2D-CRISTINA method was extended to 3D. This experimental study investigated the use and results of a new sequence, 3D-CRISTINA, on a phantom and healthy volunteers.

Methods: The 3D Cartesian single and triple-quantum imaging of Na (3D-CRISTINA) was developed and implemented at 7T, favoring a non-selective volume excitation for increased signal-to-noise ratio (SNR) and lower energy deployment than its 2D counterpart.

Comparative analysis of SINC-shaped and SLR pulses performance for contiguous multi-slice fast spin-echo imaging using metamaterial-based MRI.

Objective: To comparatively assess the performance of highly selective pulses computed with the SLR algorithm in fast-spin echo (FSE) within the current radiofrequency safety limits using a metamaterial-based coil for wrist magnetic resonance imaging.

Methods: Apodized SINC pulses commonly used for clinical FSE sequences were considered as a reference. Selective SLR pulses with a time-bandwidth product of four were constructed in the MATPULSE program.

Effect of empagliflozin on ectopic fat stores and myocardial energetics in type 2 diabetes: the EMPACEF study.

Background: Empagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor that has demonstrated cardiovascular and renal protection in patients with type 2 diabetes (T2D). We hypothesized that empaglifozin (EMPA) could modulate ectopic fat stores and myocardial energetics in high-fat-high-sucrose (HFHS) diet mice and in type 2 diabetics (T2D).

Methods: C57BL/6 HFHS mice (n = 24) and T2D subjects (n = 56) were randomly assigned to 12 weeks of treatment with EMPA (30 mg/kg in mice, 10 mg/day in humans) or with placebo.

Semiautomatic quantification of abdominal wall muscles deformations based on dynamic MRI image registration.

Quantitative analysis of abdominal organs motion and deformation is crucial to better understand biomechanical alterations undermining respiratory, digestive or perineal pathophysiology. In particular, biomechanical characterization of the antero-lateral abdominal wall is central in the diagnosis of abdominal muscle deficiency. Here, we present a dedicated semiautomatic dynamic MRI postprocessing method enabling the quantification of spatial and temporal deformations of the antero-lateral abdominal wall muscles.