Longitudinal reproducibility of brain and spinal cord quantitative MRI biomarkers.

Quantitative MRI (qMRI) promises better specificity, accuracy, repeatability, and reproducibility relative to its clinically-used qualitative MRI counterpart. Longitudinal reproducibility is particularly important in qMRI. The goal is to reliably quantify tissue properties that may be assessed in longitudinal clinical studies throughout disease progression or during treatment.

Body size and intracranial volume interact with the structure of the central nervous system: A multi-center in vivo neuroimaging study.

Clinical research emphasizes the implementation of rigorous and reproducible study designs that rely on between-group matching or controlling for sources of biological variation such as subject's sex and age. However, corrections for body size (i.e.

Multi-center benchmarking of cervical spinal cord RF coils for 7 T MRI: A traveling spines study.

Purpose: The depth within the body, small diameter, long length, and varying tissue surrounding the spinal cord impose specific considerations when designing RF coils. The optimal coil configuration for 7 T cervical spinal cord MRI is unknown and currently there are very few coil options. The purpose of this work was (1) to establish a quality control protocol for evaluating 7 T cervical spinal cord coils, and (2) to use that protocol to evaluate the performance of four different coil designs.

Multi-center benchmarking of cervical spinal cord RF coils for 7 T MRI: A traveling spines study.

Purpose: The depth within the body, small diameter, long length, and varying tissue surrounding the spinal cord impose specific considerations when designing radiofrequency coils. The optimal coil configuration for 7 T cervical spinal cord MRI is unknown and, currently, there are very few coil options. The purpose of this work was (1) to establish a quality control protocol for evaluating 7 T cervical spinal cord coils and (2) to use that protocol to evaluate the performance of 4 different coil designs.

On the impact of B0 shimming algorithms on single-voxel MR spectroscopy.

Purpose: To assess the impact of different B0 shimming algorithms on MRS.

Methods: B0 field maps and single-voxel MR spectroscopy were acquired in the prefrontal cortex of five volunteers at 3 T using five different B0 shimming approaches. B0 shimming was achieved using Siemens' proprietary shim algorithm, in addition to the Pseudo-Inverse (PI), Quadratic Programming (QuadProg), Least Squares (LSq), and Gradient optimization (Grad) algorithms.

RF shimming in the cervical spinal cord at 7 T.

Purpose: Advancing the development of 7 T MRI for spinal cord imaging is crucial for the enhanced diagnosis and monitoring of various neurodegenerative diseases and traumas. However, a significant challenge at this field strength is the transmit field inhomogeneity. Such inhomogeneity is particularly problematic for imaging the small, deep anatomical structures of the cervical spinal cord, as it can cause uneven signal intensity and elevate the local specific absorption ratio, compromising image quality.

Calibration-free parallel transmission of the cervical, thoracic, and lumbar spinal cord at 7T.

Purpose: To address the limitations of spinal cord imaging at ultra-high field (UHF) due to time-consuming parallel transmit (pTx) adjustments. This study introduces calibration-free offline computed universal shim modes that can be applied seamlessly for different pTx RF coils and spinal cord target regions, substantially enhancing spinal cord imaging efficiency at UHF.

Methods: A library of channel-wise relative maps for the cervical spinal cord (six datasets) and thoracic and lumbar spinal cord (nine datasets) was constructed to optimize transmit homogeneity and efficiency for these regions.

Shimming toolbox: An open-source software toolbox for B0 and B1 shimming in MRI.

Purpose: Introduce Shimming Toolbox ( https://shimming-toolbox.org), an open-source software package for prototyping new methods and performing static, dynamic, and real-time B0 shimming as well as B1 shimming experiments.

Methods: Shimming Toolbox features various field mapping techniques, manual and automatic masking for the brain and spinal cord, B0 and B1 shimming capabilities accessible through a user-friendly graphical user interface.

Comparison of multicenter MRI protocols for visualizing the spinal cord gray matter.

Purpose: Spinal cord gray-matter imaging is valuable for a number of applications, but remains challenging. The purpose of this work was to compare various MRI protocols at 1.5 T, 3 T, and 7 T for visualizing the gray matter.

Centering inclusivity in the design of online conferences-An OHBM-Open Science perspective.

As the global health crisis unfolded, many academic conferences moved online in 2020. This move has been hailed as a positive step towards inclusivity in its attenuation of economic, physical, and legal barriers and effectively enabled many individuals from groups that have traditionally been underrepresented to join and participate. A number of studies have outlined how moving online made it possible to gather a more global community and has increased opportunities for individuals with various constraints, e.

Impact of magnetic susceptibility anisotropy at 3 T and 7 T on T2*-based myelin water fraction imaging.

Purpose: Myelin Water Fraction (MWF) mapping can be achieved by fitting multi-gradient recalled echo (MGRE) magnitude images with a three-component model or a pseudo-continuous T distribution. Recent findings of compartment-specific orientation-dependent magnetic susceptibility shifts have spurred the inclusion of frequency offset (Δf) terms in the fitting models. In this work, we performed simulations to assess the impact of Δf's on the MWF, derived from three different fitting models, at two field strengths.

Multi-gradient-echo myelin water fraction imaging: Comparison to the multi-echo-spin-echo technique.

Purpose: Myelin water fraction (MWF) mapping based on multi-gradient recalled-echo (MGRE) imaging has been proposed as an alternative to the conventional multi-echo-spin-echo (MESE) approach. In this work, we performed a comparative study of MESE and MGRE-derived MWFs in the same subject group.

Methods: MESE and MGRE data were acquired in 12 healthy volunteers at 3T.

Field inhomogeneity correction for gradient echo myelin water fraction imaging.

Purpose: Recently, the multi-echo gradient echo (MGRE) sequence has been proposed for multicomponent T2* (MC T2*) based myelin water fraction (MWF) mapping. This approach has appeal because it can provide fast whole-brain coverage, has low specific absorption rate, and short echo spacing. However, the MGRE signal requires correction for accurate MWF mapping, because of its sensitivity to magnetic field inhomogeneities (ΔB ).

MRI-based myelin water imaging: A technical review.

Multiexponential T2 relaxation time measurement in the central nervous system shows a component that originates from water trapped between the lipid bilayers of myelin. This myelin water component is of significant interest as it provides a myelin-specific MRI signal of value in assessing myelin changes in cerebral white matter in vivo. In this article, the various acquisition and analysis strategies proposed to date for myelin water imaging are reviewed and research conducted into their validity and clinical applicability is presented.