Keywords: Spinal Cord, Spinal Cord

Motivation: The necessity to accurately delineate microstructural changes in the spinal cords of MS and NMOSD patients in vivo.

Goal(s): Assess if multiple b-tensor diffusion MRI data enhances the clinical utility of Micro Fractional Anisotropy (μFA) in distinguishing pathological variances in MS and NMOSD.

Approach: Comparative analysis of μFA values derived from planar tensor encoding data (DDE) and a combination of DDE with linear tensor encoding data was conducted.

Results: No significant μFA difference between MS and NMOSD was found, and additional linear tensor encoding data did not improve the results, highlighting the need for optimized imaging protocols.

Impact: This study elucidates the criticality of optimizing imaging protocols over merely aggregating data for precise diagnostic outcomes in MS and NMOSD. It prompts further investigation into refining imaging methodologies to uncover microstructural changes, enhancing diagnostic accuracy and subsequent patient management.

Keywords: White Matter, Tractography & Fibre Modelling, Tractometry, Parcellation

Motivation: The subdivision of WM tracts into individual parcels required for tractometry analysis, suffers from blurred parcel borders and wrong assignments of complete tract regions, particularly in fanning tracts.

Goal(s): The goal of this work is to overcome these limitations with a new parcellation approach that yields clearly delineated tract parcels and avoids wrong parcel assignments even in challenging tracts. 

Approach: We propose a self-supervised approach based on optimally separating hyperplanes, obtained using large-margin classifiers, to separate tracts into parcels.

Results: We compare our approach to two popular state-of-the-art approaches and clearly show markedly improved results in 24 tracts and 98 subjects.

Impact: A new method to parcellate tracts for fiber tractometry, avoiding frequent errors of state-of-the-art approaches, particularly in complex tracts with a fanning topology. This might lead to improved tractometry analysis and potentially insights that were not possible with previous approaches.

Keywords: Other Neurodegeneration, CEST & MT

Motivation: Quantifying myelin content in 0.3 T low-field MRI presents a challenge owing to prolonged imaging times and a low signal-to-noise ratio.

Goal(s): The study aimed to validate the practical feasibility of macromolecular proton fraction (MPF) mapping in the brain using a 0.3 T MRI system.

Approach: A phantom study with protein samples and an in vivo investigation were conducted.

Results: The study findings indicate a robust correlation between 0.3 T MPF in brain tissue, MPF at 3.0 T, and previously reported MPF at 0.5 T.

Impact: The fast single-point MPF mapping using a 0.3 T MRI exhibited the capacity to accurately measure brain MPF in a clinically feasible timeframe, providing a valuable tool for assessing myelin content. 

Keywords: White Matter, Diffusion/other diffusion imaging techniques, High performance gradient inserts, cross-site, repeatability, reproducibility

Motivation: Cross-site reproducibility of ultra-high b-value diffusion MRI across multiple MAGNUS MRI systems is important for multi-site studies

Goal(s): To disentangle the contributions of physiological fluctuations vs. manufacturing tolerances to inform future cross-site studies for advanced and novel brain microstructural modelling and quantification

Approach: A traveling volunteer was recruited and imaged at three different MAGNUS (2^nd generation) systems. An expanded multi-shell parameter space ranging from b=500-30,000 s/mm² was analysed quantitatively to assess cross-site reproducibility. 

Results: Statistical comparisons across sites for global white matter and white matter parcels highlight good agreement without harmonization efforts.

Impact: This dataset is expected to lay the ground work for multicenter collaboration for novel and advanced brain microstructural modelling and quantification. It can further be used to evaluate differences across scanners and to show the consistency of pipeline outputs.

Keywords: White Matter, Brain Connectivity, High performance gradient MRI, WM plasticity, Learning, Dynamic white matter plasticity

Motivation: To investigated whether white matter microstructural changes after adaptive short-term training can be detected in a limited sample size with a high-performance gradient system that allows for increased sensitivity to underlying brain micro-architecture.

Goal(s): Demonstrate that with task complexity and short-term training, the dynamic-location-specific neuroplastic changes can be detected.

Approach: Advanced structural and functional MRI sequences in <60-min examination with a pre- and post-design paradigm were used in a high-performance head gradient system that allows for increased sensitivity to the underlying brain micro-architecture.

Results: In this pilot study microstructural changes were noted on a group basis underlying primary motor and sensorimotor cortices. 

Impact: This study highlights the role of dynamic brain processes following short term visual motor sequencing learning (VMSL). The adult brain preserves dynamic characteristics that are altered by short-term learning experiences that can be detected with dMRI.

Keywords: Neuro, Diffusion Tensor Imaging, Cerebral palsy

Motivation: A biomarker of motor system function is needed to assist with treatment selection for children with cerebral palsy (CP).

Goal(s): We aimed to pilot an automated tractography tool in a clinical trial cohort of adolescents with CP, and determine if corticospinal tract (CST) integrity could be used as a biomarker for baseline function and treatment response.

Approach: A customised probabilistic tractography pipeline was used to quantify CST integrity. Hand function was assessed at baseline and after a motor training intervention.

Results: We demonstrated feasibility, and found that CST integrity was positively correlated with baseline hand function, and negatively correlated with improvement after training. 

Impact: Automated individualised native-space tractography is feasible in a clinical population of adolescents with cerebral palsy. Tractography-derived corticospinal tract integrity predicts baseline hand function impairment and may be useful as a predictive biomarker for rehabilitation response.

Keywords: White Matter, Brain, myelin water imaging, Gradient Echo Spin Echo (GRASE))

Motivation: Myelin water fraction (MWF) is conventionally measured using the T₂ decay curve. Due to hardware limitations, for spin-echo based sequences, TR and TE times were restricted by SAR and gradient slew rate.

Goal(s): Our objective is to reduce the total scan time by shortening the TR time. A shorter TE time should also capture more signal from the short T₂ components of myelin water.

Approach: We implemented myelin water imaging (MWI) on the MAGNUS system with reduced TR and TE times.

Results: When implemented on the MAGNUS system, MWI could be carried out in a shorter time and the MWF were slightly larger.

Impact: The work aims to optimize MWI by shortening scan times. It successfully achieves this, leading to quicker, high-quality MWI acquisition, benefiting medical diagnostics and research efficiency.

Keywords: Spinal Cord, Spinal Cord, Cervical Spondylotic Myelopathy; Diffusion Magnetic Resonance Imaging

Motivation: Early cervical spondylotic myelopathy (CSM) is challenging to diagnose and easily missed. 

Goal(s): To explore the value of diffusion MRI (dMRI) in diagnosing early-stage CSM and evaluating uncompressed segments in patients with early CSM.

Approach:  Using diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), and neurite orientation dispersion and density imaging (NODDI), a 1:1 matched case control study was conducted.

Results: The orientation division index (ODI) was positively correlated with early CSM, and the anisotropic water fraction (AWF) was negatively correlated. The ODI and AWF can assist in identifying the scope of early CSM involvement.

Impact: The orientation division index (ODI) was positively correlated with early CSM, and the anisotropic water fraction (AWF) was negatively correlated. The ODI and AWF can assist in identifying the scope of early CSM involvement.

Keywords: White Matter, Brain, Adrenoleukodystrophy, Leriglitazone, Volumetric analysis, Diffusion Tensor Imaging

Motivation: Cerebral adrenoleukodystrophy (CALD) is a rare and devastating demyelinating disease. The standard of care is hematopoeitic stem cell transplantation (HCST), which efficacy is limited to early-stage patients.

Goal(s): We studied the efficacy of Leriglitazone in CALD patients, either not eligible or awaiting HSCT.

Approach: Leriglitazone was administered to thirteen adult male patients. They underwent brain MRI every 3 months, with a quantitative analysis of lesion volumes on FLAIR, diffusion tensor parameters and gadolinium enhancements.  

Results: The disease stabilized in all patients awaiting HSCT. Corticospinal tract lesions downsized in most patients and turned gadolinium-negative, showing a selective effect of this molecule on motor pathways. 

Impact: Cerebral adrenoleukodystrophy is a devastating demyelinating disease, fatal for all patients without early stem cell transplantation. We showed that Leriglitazone represents a therapeutic alternative, allowing clinical and radiological stabilization in ten men. Remarkably, motor pathways lesions downsized and turned gadolinium-negative.  

Keywords: Spinal Cord, Spinal Cord, reduced-FOV, multi-shot DTI

Motivation: To our best knowledge, there has yet to be a comprehensive evaluation of the combination of cardiac triggering, reduced-FOV, or multi-shot techniques together for improving spinal cord DTI. 

Goal(s): This study aims to compare the performances of spinal cord DTI with different parametric combinations.

Approach: Extensive and comparative experiments in five aspects were conducted.

Results: Results demonstrate that multi-shot DTI with MUSE could achieve better reconstruction in the spinal cord. A combination of reduced-FOV and multi-shot techniques could be adopted simultaneously in pursuit of ultimate distortion correction. In addition, cardiac triggering should be equipped to reduce the influences on cerebrospinal fluid pulsation.

Impact: Multi-shot DTI with MUSE and cardiac triggering might be the optimal combination for clinical diagnosis of the spinal cord if available on commercial MRI scanners. Future coil design could focus on customized coil arrangement of the spinal cord for optimization.

Keywords: Spinal Cord, Microstructure, Diffusion Tensor Imaging

Motivation: While diffusion tensor imaging (DTI) is sensitive to spinal cord injury (SCI)-induced microstructural changes, manual pre-processing of thoracolumbar spinal cord (TL-SC) data precludes its clinical translation.

Goal(s): We aimed to optimise a semi-automatic TL-SC DTI protocol to detect SCI-induced microarchitectural changes.

Approach: TL-SC DTI data from two participants with diagnosed SCI and six healthy volunteers were pre-processed to equate the TL-SC microarchitecture and then compared to semi-automated analysis.

Results: Our optimised TL-SC DTI acquisition and semi-automatic analysis pipeline is sensitive to SCI-induced microstructural changes and may provide a more clinically viable method for TL-SC DTI analysis.

Impact: This study assessed and validated our newly developed thoracolumbar spinal cord (TL-SC) diffusion tensor imaging (DTI) pipeline in detecting spinal cord injury (SCI)-induced microstructural changes and offers an alternative semi-automatic pre-processing method for improved clinical translation.

Keywords: Tractography, Tractography & Fibre Modelling

Motivation: Lateralization of structural connectomes has become a widespread measurement for investigating brain asymmetry alterations during brain development, maturation and aging in health and disease. However, it is still unclear whether the acquisition parameters affect the lateralization measurement of structural connectomes.

Goal(s): We aim to investigate the TE-dependence of lateralization of structural connectomes.

Approach: We compared the lateral indices of structural connectivity generated by diffusion MRI on five different TEs.

Results: Diverse TE values in MRI scans lead to apparent differences in connectome lateralization, with more than 30% of connections of the same subject likely to have different lateral indices.

Impact: This research reveals the unknown relationship between TE and connectome lateralization and discover the potential influence of TE in connectome’s anatomy analysis, helping improve the acquisition protocol of future neuroimaging studies, especially in brain asymmetry during development, maturation and aging.

Keywords: Aging, Relaxometry, Transcriptomics, Myelin water fraction

Motivation: Myelin water imaging has demonstrated its ability to successfully detect changes of myelin content in different neuropathology. However, the validation of these measures remains challenging.

Goal(s): In this study, we aim to validate our MWF measurements with the gene expression that are relevant to myelin.

Approach: We utilized the Allen Human Brain Atlas (AHBA) transcriptomics dataset to validate our Myelin Water Fraction (MWF) measurements. We correlated the aggregated gene expression from AHBA with our derived MWF for different brain regions. 

Results: Our results demonstrate strong correlations of gene expression related to myelin and the transcription of myelin with derived MWF measurements.

Impact: We utilized transcriptomics to validate derived Myelin Water Fraction measures, which strongly correlated with the gene expression specific to myelin. The use of transcriptomics further supports on the molecular basis of myelin synthesis and transcriptional changes with aging.

Keywords: White Matter, Drugs, tMRI, Delayed Hypoxic Leukoencephalopathy, Drug Overdose

Motivation: Divided Subtracted Inversion Recovery (dSIR) sequences can show subtle abnormalities due to small increases in T₁ that are not seen with conventional sequences,

Goal(s): To use dSIR sequences to examine the brain in a patient nine months after severe drug overdose associated with prolonged hypoxia and compare the dSIR images with T2-FLAIR images.

Approach: MRI scans obtained on an 18-y/o male control and a 19-y/o male patient. 2D IR FSE sequences were performed with TI_s chosen to null WM, and a longer TI_i producing dSIR images.

Results: Widespread abnormalities seen on dSIR images in areas of WM that appeared normal on T₂-FLAIR images.

Impact: In a patient imaged nine months after a severe drug overdose, dSIR images showed extensive abnormalities in white matter that appeared normal on T2-FLAIR images. Widespread white matter changes may be common unrecognised sequelae of severe drug overdoses.

Keywords: Spinal Cord, Spinal Cord

Motivation: Myelin water fraction (MWF) is a promising method for quantitative evaluation of myelin function in the brain. On the other hand, myelin-sensitive inversion recovery (MySIR) sequence is thought to show spinal myelin structure. 

Goal(s):  To evaluate the feasibility of MySIR imaging for myelin visualization in the cervical spinal cord. .

Approach: MySIR images were compared with MWF as the gold standard.

Results: We have demonstrated that MySIR showed similar results to MWF in evaluating the distribution of myelin in the spine. MySIR may be useful for evaluating the distribution of myelin.

Impact: MySIR gave us a novel contrast between grey matter and white matter. Additionally, MySIR showed similar results to MWF in evaluating myelin.　We demonstrated the feasibility of MySIR for evaluating the distribution of myelin in cervical spine.

Keywords: Spinal Cord, Relaxometry, Quantitative Magnetization Transfer, C-spine

Motivation: We proposed to use a method known as selective inversion recovery (SIR), which allows one to perform the entire QMT (quantitative magnetization transfer) experiment from a conventional inversion recovery sequence. 

Goal(s): To translate the SIR-QMT method to the spinal cord at 3T with optimized sampling schemes to yield high-resolution cervical spinal cord PSR (macromolecular pool-size-ratios) maps within clinically relevant scan times.

Approach: SIR-QMT was conducted on two healthy volunteers to calculate PSR and R_1f.

Results: These results suggest that QMT imaging can be performed in the human cervical spinal cord at 3T.

Impact: The work has important clinical indication to study de/remyelination and nerve injuries/repairs in spinal cord disorders.