Advanced Magnetic Resonance Imaging Biomarkers of the Injured Spinal Cord: A Comparative Study of Imaging and Histology in Human Traumatic Spinal Cord Injury.

A significant problem in the diagnosis and management of traumatic spinal cord injury (tSCI) is the heterogeneity of secondary injury and the prediction of neurological outcome. Imaging biomarkers specific to myelin loss and inflammation after tSCI would enable detailed assessment of the pathophysiological processes underpinning secondary damage to the cord. Such biomarkers could be used to biologically stratify injury severity and better inform prognosis for neurological recovery.

Quantitative MRI Biomarkers Measure Changes in Targeted Brain Areas in Patients With Obesity.

Context: Obesity is accompanied by damages to several tissues, including the brain. Pathological data and animal models have demonstrated an increased inflammatory reaction in hypothalamus and hippocampus.

Objective: We tested whether we could observe such pathological modifications in vivo through quantitative magnetic resonance imaging (MRI) metrics.

Inhomogeneous Magnetization Transfer (ihMT) imaging in the acute cuprizone mouse model of demyelination/remyelination.

Background: To investigate the association of ihMT (inhom signals with the demyelination and remyelination phases of the acute cuprizone mouse model in comparison with histology, and to assess the extent of tissue damage and repair from MRI data.

Methods: Acute demyelination by feeding 0.2% cuprizone for five weeks, followed by a four-week remyelination period was applied on genetically modified plp-GFP mice.

Quantitative myelin imaging with MRI and PET: an overview of techniques and their validation status.

Myelin is the protective sheath wrapped around axons, consisting of a phospholipid bilayer with water between the wraps. The measurement of damage to the myelin sheaths, the evaluation of the efficacy of therapies aiming to promote remyelination and monitoring the degree of brain maturation in children all require non-invasive quantitative myelin imaging methods. To date, various myelin imaging techniques have been developed.

Visualization of the saccule and utricle with non-contrast-enhanced FLAIR sequences.

Objectives: 3D-fluid attenuation inversion recovery (FLAIR) collected 4 h after intravenous gadolinium injection can delineate the perilymphatic space (PLS) from the endolymphatic space (ELS) to capture endolymphatic hydrops, the pathological counterpart of Ménière's disease. We aimed to optimize visualization of such inner ear internal anatomy using 3D-FLAIR without injection.

Methods: 3D-FLAIR signal from different fluid compartments such as PLS and ELS was first simulated.

Temperature dependence and histological correlation of inhomogeneous magnetization transfer and myelin water imaging in ex vivo brain.

Purpose: The promise of inhomogeneous magnetization transfer (ihMT) as a new myelin imaging method was studied in ex vivo human brain tissue and in relation to myelin water fraction (MWF). The temperature dependence of both methods was characterized, as well as their correspondence with a histological measure of myelin content. Unfiltered and filtered ihMT protocols were studied by adjusting the saturation scheme to preserve or attenuate signal from tissue with short dipolar relaxation time T.

The Aging Imageomics Study: rationale, design and baseline characteristics of the study population.

Biomarkers of aging are urgently needed to identify individuals at high risk of developing age-associated disease or disability. Growing evidence from population-based studies points to whole-body magnetic resonance imaging's (MRI) enormous potential for quantifying subclinical disease burden and for assessing changes that occur with aging in all organ systems. The Aging Imageomics Study aims to identify biomarkers of human aging by analyzing imaging, biopsychosocial, cardiovascular, metabolomic, lipidomic, and microbiome variables.

Whole brain inhomogeneous magnetization transfer (ihMT) imaging: Sensitivity enhancement within a steady-state gradient echo sequence.

Purpose: To implement, characterize, and optimize an interleaved inhomogeneous magnetization transfer (ihMT) gradient echo sequence allowing for whole-brain imaging within a clinically compatible scan time.

Theory And Methods: A general framework for ihMT modelling was developed based on the Provotorov theory of radiofrequency saturation, which accounts for the dipolar order underpinning the ihMT effect. Experimental studies and numerical simulations were performed to characterize and optimize the ihMT-gradient echo dependency with sequence timings, saturation power, and offset frequency.

In vivo measurement of a new source of contrast, the dipolar relaxation time, T , using a modified inhomogeneous magnetization transfer (ihMT) sequence.

Purpose: This paper describes a technique that can be used in vivo to measure the dipolar relaxation time, T , of macromolecular protons contributing to magnetization transfer (MT) in tissues and to produce quantitative T maps.

Theory And Methods: The technique builds upon the inhomogeneous MT (ihMT) technique that is particularly sensitive to tissue components with long T . A standard ihMT experiment was altered to introduce a variable time for switching between positive and negative offset frequencies for RF saturation.

Magnetization transfer from inhomogeneously broadened lines (ihMT): Improved imaging strategy for spinal cord applications.

Purpose: Inhomogeneous magnetization transfer (ihMT) shows great promise for specific imaging of myelinated tissues. Whereas the ihMT technique has been previously applied in brain applications, the current report presents a strategy for cervical spinal cord (SC) imaging free of cerebrospinal fluid (CSF) pulsatility artifacts.

Methods: A pulsed ihMT preparation was combined with a single-shot HASTE readout.

Minimizing the effects of magnetization transfer asymmetry on inhomogeneous magnetization transfer (ihMT) at ultra-high magnetic field (11.75 T).

Objectives: The recently reported inhomogeneous magnetization transfer technique (ihMT) has been proposed for specific imaging of inhomogeneously broadened lines, and has shown great promise for characterizing myelinated tissues. The ihMT contrast is obtained by subtracting magnetization transfer images obtained with simultaneous saturation at positive and negative frequency offsets (dual frequency saturation experiment, MT (+/-)) from those obtained with single frequency saturation (MT (+)) at the same total power. Hence, ihMT may be biased by MT-asymmetry, especially at ultra-high magnetic field.

Fast imaging strategies for mouse kidney perfusion measurement with pseudocontinuous arterial spin labeling (pCASL) at ultra high magnetic field (11.75 tesla).

Background: To derive an adapted protocol at ultra high magnetic field for mouse kidney perfusion measurements using pCASL in combination with three widely available fast imaging readouts: segmented SE EPI (sSE EPI), RARE, and TrueFISP.

Methods: pCASL sSE EPI, pCASL RARE, and pCASL TrueFISP were used for the acquisition of mouse kidney perfusion images in the axial and coronal planes at 11.75T.

Magnetization transfer from inhomogeneously broadened lines (ihMT): Experimental optimization of saturation parameters for human brain imaging at 1.5 Tesla.

Purpose: Recently a new MR endogenous contrast mechanism was reported. It allows specifically imaging the magnetization transfer (MT) effect arising from inhomogeneously broadened components of the NMR spectrum, and was hence dubbed ihMT. Such unique NMR lineshape properties are presumably occurring in myelin because of its specifically ordered, multilayered sheath structure.

High-resolution mouse kidney perfusion imaging by pseudo-continuous arterial spin labeling at 11.75T.

Purpose: Quantitative measure of blood flow provides important information regarding renal function, nephropathies and viability of kidney transplantation. Therefore, a method that would allow quantitative and reliable assessment of the renal microvascular perfusion would be very valuable. Arterial spin labeling Magnetic Resonance Imaging has started to be widely used for human studies.