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.

Combining sodium MRI, proton MR spectroscopic imaging, and intracerebral EEG in epilepsy.

Whole brain ionic and metabolic imaging has potential as a powerful tool for the characterization of brain diseases. We combined sodium MRI ( Na MRI) and H-MR Spectroscopic Imaging ( H-MRSI), assessing changes within epileptogenic networks in comparison with electrophysiologically normal networks as defined by stereotactic EEG (SEEG) recordings analysis. We applied a multi-echo density adapted 3D projection reconstruction pulse sequence at 7 T ( Na-MRI) and a 3D echo-planar spectroscopic imaging sequence at 3 T ( H-MRSI) in 19 patients suffering from drug-resistant focal epilepsy who underwent presurgical SEEG.

Respiratory-triggered quantitative MR spectroscopy of the human cervical spinal cord at 7 T.

Purpose: Ultra-high field H MR spectroscopy (MRS) is of great interest to help characterizing human spinal cord pathologies. However, very few studies have been reported so far in this small size structure at these fields due to challenging experimental difficulties caused by static and radiofrequency field heterogeneities, as well as physiological motion. In this work, in line with the recent developments proposed to strengthen spinal cord MRS feasibility at 7 T, a respiratory-triggered acquisition approach was optimized to compensate for dynamic B field heterogeneities and to provide robust cervical spinal cord MRS data.

Deuterium Magnetic Resonance Imaging and the Discrimination of Fetoplacental Metabolism in Normal and L-NAME-Induced Preeclamptic Mice.

Recent magnetic resonance studies in healthy and cancerous organs have concluded that deuterated metabolites possess highly desirable properties for mapping non-invasively and, as they happen, characterizing glycolysis and other biochemical processes in animals and humans. A promising avenue of this deuterium metabolic imaging (DMI) approach involves looking at the fate of externally administered H-glucose, as it is taken up and metabolized into different products as a function of time. This study employs deuterium magnetic resonance to follow the metabolism of wildtype and preeclamptic pregnant mice models, focusing on maternal and fetoplacental organs over ≈2 h post-injection.

Deuterium MRSI characterizations of glucose metabolism in orthotopic pancreatic cancer mouse models.

Detecting and mapping metabolism in tissues represents a major step in detecting, characterizing, treating and understanding cancers. Recently introduced deuterium metabolic imaging techniques could offer a noninvasive route for the metabolic imaging of animals and humans, based on using H magnetic resonance spectroscopic imaging (MRSI) to detect the uptake of deuterated glucose and the fate of its metabolic products. In this study, H -glucose was administered to mice cohorts that had been orthotopically implanted with two different models of pancreatic ductal adenocarcinoma (PDAC), involving PAN-02 and KPC cell lines.

Fast chemical exchange saturation transfer imaging based on PROPELLER acquisition and deep neural network reconstruction.

Purpose: To develop a method for fast chemical exchange saturation transfer (CEST) imaging.

Methods: The periodically rotated overlapping parallel lines enhanced reconstruction (PROPELLER) sampling scheme was introduced to shorten the acquisition time. Deep neural network was employed to reconstruct CEST contrast images.

Brain sugar consumption during neuronal activation detected by CEST functional MRI at ultra-high magnetic fields.

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) indirectly measures brain activity based on neurovascular coupling, a reporter that limits both the spatial and temporal resolution of the technique as well as the cellular and metabolic specificity. Emerging methods using functional spectroscopy (fMRS) and diffusion-weighted fMRI suggest that metabolic and structural modifications are also taking place in the activated cells. This paper explores an alternative metabolic imaging approach based on Chemical Exchange Saturation Transfer (CEST) to assess potential metabolic changes induced by neuronal stimulation in rat brains at 17.

Brain investigations of rodent disease models by chemical exchange saturation transfer at 21.1 T.

This study explores opportunities opened up by ultrahigh fields for in vivo saturation transfer brain magnetic resonance imaging experiments. Fast spin-echo images weighted by chemical exchange saturation transfer (CEST) effects were collected on Sprague-Dawley rats at 21.1 T, focusing on two neurological models.

Placental physiology monitored by hyperpolarized dynamic C magnetic resonance.

Placental functions, including transport and metabolism, play essential roles in pregnancy. This study assesses such processes in vivo from a hyperpolarized MRI perspective. Hyperpolarized urea, bicarbonate, and pyruvate were administered to near-term pregnant rats, and all metabolites displayed distinctive behaviors.

Metabolic assessment of a migraine model using relaxation-enhanced H spectroscopy at ultrahigh field.

Purpose: This study evaluates biochemical imbalances in a rat model that reflects dysfunctional pathways in migraine. The high sensitivity and spectral dispersion available to H MRS at 21.1 T expands metabolic profiling in this migraine model to include lactate (Lac), taurine (Tau), aspartate, and Gly-a mixture of glycine, glutamine, and glutamate.

fMRI contrast at high and ultrahigh magnetic fields: insight from complementary methods.

This manuscript examines the origins and nature of the function-derived activation detected by magnetic resonance imaging at ultrahigh fields using different encoding methods. A series of preclinical high field (7 T) and ultra-high field (17.2 T) fMRI experiments were performed using gradient echo EPI, spin echo EPI and spatio-temporally encoded (SPEN) strategies.

Hyperpolarized functional magnetic resonance of murine skeletal muscle enabled by multiple tracer-paradigm synchronizations.

Measuring metabolism's time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water's sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites.