Keywords: Multiple Sclerosis, Multiple Sclerosis, Network analysis, Structural disconnection, Morphometric similarity

Motivation: Multiple sclerosis can be modelled as a network disorder. Progressive demyelination and neurodegeneration lead to structural disconnection and disruption of the morphometric similarity between gray matter regions.

Goal(s): To obtain measures of structural disconnection and morphometric similarity networks from conventional MRI sequences and test whether they are sensitive to disease status and clinical disability.

Approach: 461 patients were imaged. Using publicly available software, we computed structural disconnection using white matter lesions masks and normative tractography atlases. Likewise, morphometric similarity was computed from standard FreeSurfer outputs.

Results: Structural disconnection and morphometric similarity networks are sensitive to disease status and explain clinical disability.

Impact: Measures of structural disconnection and morphometric similarity networks obtained from conventional MRI sequences are sensitive to multiple sclerosis and its related physical and cognitive disability. Our approach could represent a way to overcome the limitations of the standard network analyses.

Keywords: Radiomics, Modelling, Mixture-Modeling, White Matter Lesions

Motivation: Analyzing multiple sclerosis (MS) lesions longitudinally is challenging, and requires consistent and robust imaging, processing, and statistical methods. Conventional binary lesion segmentations might overlook significant pathology changes as degeneration is continuous. 

Goal(s): To track subtle changes in MS lesions using statistically derived metrics. 

Approach: We introduced a two-component Mixture Model (MM) to track longitudinal changes qT1 with regions of interest (ROIs) and compared it with conventional image metrics.

Results: In our longitudinal analysis, the MM approach uncovered changes missed by traditional methods suggesting MM may help capture and understand longitudinal evolution of MS lesions.

Impact: Our novel mixture modeling analysis approach may untangle unique aspects of biological processes in MS lesion evolution, offering a valuable alternative to conventional image analysis methods.

Keywords: Functional/Dynamic, Spectroscopy

Motivation: Bridge the knowledge gap in understanding the central mechanisms of chronic low back pain (CLBP) and the effects of spinal manipulation (SM).

Goal(s): To use 1H-MRS to investigate metabolic differences in the posterior cingulate cortex (PCC) during spinal manipulation for chronic low back pain (CLBP).

Approach: The approach involved recruiting CLBP patients and healthy controls, performing 1H-MRS in the posterior cingulate cortex (PCC) before and after spinal manipulation (SM), and correlating metabolite changes with clinical outcomes.

Results: CLBP patients exhibited altered brain metabolism in the posterior cingulate cortex (PCC), with changes in specific metabolites, and these abnormalities improved after spinal manipulation (SM).

Impact: The research provides insights into the central mechanisms of chronic low back pain (CLBP) and the potential therapeutic benefits of spinal manipulation, which could inform better pain management strategies.

Keywords: White Matter, Brain, Autism Spectrum Disorder, Precision Medicine, Replicability

Motivation: Heterogeneity of neuroimaging findings remains a challenge to identify specific brain-related phenotypes in ASD. Quantitative metrics of individual deviation across brain measurements are needed for parsing variation and identifying individuals who may or may not have abnormal brain structure.

Goal(s): This study aims to quantify individual brain differences in individuals with and without ASD.

Approach: We investigated the Mahalanobis distance to characterize multidimensional brain measures of microstructure in individuals with and without ASD in a set of white matter regions.

Results: We found multivariate Mahalanobis distance is superior to univariate comparisons at distinguishing between individuals with and without ASD.

Impact: Normative modeling and multivariate approaches may provide informative metrics for parsing heterogeneity in the multivariate patterns of brain development in autistic individuals.

Keywords: White Matter, Brain

Motivation: Chronic hypoperfusion is a central mechanism of cerebral small vessel disease (CSVD), but studies using different methods have shown different results.

Goal(s): To compare the associations between CSVD and CBF measured by phase-contrast MRI and ASL in the same cohort.

Approach: 69 subjects were totally recruited in the study. WMH, FW, and tFA were used to reflect the disease severity. The associations between CSVD and CBF measured by two methods were investigated.

Results: Compared to CBF_PC, CBF_ASL showed a negative association with FW and a positive association with tFA. The ratio of CBF_ASL to CBF_PC was also correlated with FW and tFA.

Impact: Future studies need to consider the differences between CBF measured by ASL and phase-contrast MRI and choose a more appropriate method according to the research purpose.

Keywords: White Matter, Kidney, hemodialysis

Motivation: The relationship between white matter hyperintensity (WMH) and altered cerebral blood flow (CBF) in maintenance hemodialysis patients remains unclear.

Goal(s): The study aims to explore the regulation of changes for CBF and its relationship with WMH burden in hemodialysis patients.

Approach: Hemodialysis patients were divided into two groups based on whether their CBF decreased after 3-year therapy. The severity of white matter hyperintensity was compared between the two groups.

Results: Compared with the increased CBF group, higher burden of deep WMH was found in the decreased CBF group.

Impact:  This association between WMH and decrased CBF in maintenance hemodialysis be beneficial to the exploration of the complex mechanisms underlying the development of cerebral abnormalities during hemodialysis.

Keywords: White Matter, Neurodegeneration

Motivation: The factors that influence iron deposition in the normal-appearing white matter (NAWM) of the brain have yet to be thoroughly examined.

Goal(s): This study aimed to measure brain iron levels in a community population and identify factors affecting NAWM iron levels.

Approach: Brain iron load was assessed using quantitative susceptibility mapping.

Results: Age, hypertension, T2DM, smoking, BMI, and APOE4 affect iron metabolism in certain NAWM brain regions. Moreover, the mean susceptibility values of the corpus callosum are significantly related to some cognitive tests.

Impact: We could identify the potential factors that could affect iron levels in the white matter and accurately map iron in this part of the brain. This information could help us better control confounding variables in future research.

Keywords: White Matter, White Matter, Aging, Small Vessel Disease, Neurodegeneration

Motivation: Dirty-appearing white matter (DAWM) might be an early marker of cerebral small vessel disease (SVD) progression.

Goal(s): To investigate whether dirty-appearing white matter (DAWM) on brain MRI is related to long-term progression of SVD markers in a cohort of community-dwelling older adults.

Approach: We visually rated DAWM volume fraction on baseline FLAIR images (n=2506) and related this to progression of multiple SVD MRI markers at the 5.2-year follow-up.

Results: Global and occipital DAWM is associated with an increase in global white matter hyperintensity (WMH) volume at follow-up. This suggests that DAWM is an early marker of SVD, preceding WMH.

Impact: The presence of DAWM on MRI might help in early risk stratification of older adults at risk for cognitive decline due to SVD, and in that way allow for selection of individuals for preventive lifestyle interventions and treatment trials.

Keywords: White Matter, White Matter, obsessive-compulsive disorder

Motivation: Diffusion tensor imaging (DTI) is a useful imaging technique to investigate white matter (WM) integrity and previous studies had revealed the disruption of WM related to neuropathology in obsessive-compulsive disorder (OCD). However, few study had reliably located the defect at track level.

Goal(s): To investigate the WM integrity in OCD on a whole brain level using newly developed tractography method.

Approach: We used Tracts Constrained by Underlying Anatomy (TRACULA) software to investigate the WM integrity in OCD.

Results: We found widespread disruption of WM integrity in OCD, and for the first time, we observed abnormality in bilateral acoustic radiation in OCD.

Impact: Using the innovated fiber tractography methodology, we were able to detect abnormality in bilateral acoustic radiation in OCD, which had been suggested by previous study using resting state fMRI.

Keywords: White Matter, Fetus

Motivation: There is a controversial argue about the prognosis of fetuses with isolated ventriculomegaly in clinical practice.

Goal(s): Application of diffusion Magnetic Resonance Imaging (dMRI) in fetuses with isolated ventriculomegaly to explore structure changes of white matter fibers.

Approach: Collecting brain dMRI data in isolated ventriculomegaly and healthy fetuses, analyzing differences in white matter structure between the two groups using diffusion tensor imaging (DTI) and fixel based analysis (FBA) methods.

Results: Significant differences were found in DTI or FBA parameters of white matter fibers including the inferior longitudinal fasciculus, corpus callosum, fornix, sagittal stratum and corticospinal tract between the two groups.

Impact: There are changes in the brain white matter structure in intrauterine fetuses with isolated ventriculomegaly, which provides a certain objective basis for potential risks of neurodevelopmental disorders and prenatal counseling.

Keywords: Neurotransmission, Quantitative Imaging, systemic lupus erythematosus; quantitative MRI; white matter microstructure

Motivation: Neuropsychiatric disorders are common symptoms in systemic lupus erythematosus (SLE) patients. However, investigations into altered white matter (WM) microstructure caused by SLE were insufficient.

Goal(s): Investigate WM microstructure alterations and their association with anxiety and depression in SLE patients using synthetic MRI (SyMRI) technique.

Approach: T1, T2 and myelin content, acquired by SyMRI, were compared between 52 SLE patients and 24 health controls.

Results: Longer T1 relaxation time and lower myelin content were found in several WM regions, and anxiety in SLE patients was found to be correlated with a decrease in myelin content in the fornix.

Impact: The demyelination of the fornix may be a significant factor leading to anxiety in patients with systemic lupus erythematosus.

Keywords: White Matter, Neonatal

Motivation: To investigation of cerebral asymmetry in full-term newborns and alterations in the lateralization of the infant brain with white matter injury

Goal(s): To explore brain volume laterality in normal full-term newborns and the effect of infant with WMI on laterality.

Approach: Calculated asymmetry index, used non-parametrically to test the significant, compared the difference of AI with the WMI group.

Results: The distribution of lateralized significance in brain regions between groups was near the same. Significant differences were found between the groups in the hippocampus, amygdala, superior temporal gyrus middle part GM, occipital lobe GM, superior temporal gyrus middle part WM, and caudate nucleus.

Impact: WMI can cause localized lateralized changes in brain regions, which may be associated with future adverse developmental outcomes and might be a biomarker for predicting prospective developmental outcomes of WMI.

Keywords: White Matter, White Matter

Motivation: White matter lesion (WML) is a neuroimaging signature of cerebral small vessel disease (CSVD), commonly comprising both vascular and nonvascular components for which assessment methods remain to be developed.

Goal(s): To investigate the feasibility of using multimodal MR imaging to separate vascular and nonvascular components in WML.

Approach: Twelve patients with CSVD were prospectively included and underwent 3T MR imaging. Magnetization transfer ratio (MTR) was derived from magnetization transfer imaging. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were derived from diffusion tensor imaging.

Results: MTR was found to correlate with ADC and FA differently in WML as compared to normal-appearing white matter.

Impact: Appropriate separation of vascular/nonvascular components in WML can help differential diagnosis and treatment formation of CSVD. The sensitivity of combined MTR/FA/ADC can be further verified by comparing CSVD with other neurological diseases that present WML but have nonvascular pathogenesis.

Keywords: White Matter, White Matter, CADASIL, WMH, longitudinal studies

Motivation: In CADASIL, the relationship between white matter hyperintensities (WMH) changes and disease progression remains unknown. 

Goal(s): To estimate WMH changes, accurate segmentations are mandatory but remain challenging to obtain automatically because of patients MRI variability and heterogeneous contrast between WMH and normal appearing white matter. We aim to decrease correction time required to reach accurate results.

Approach: We used an incremental learning approach with a supervised algorithm from baseline segmentation data up to the final follow-up data to improve results and reduce manual correction time.

Results: A significant improvement of segmentation sensitivity and a reduction of manual correction time were obtained.

Impact: To accurately investigate the WMH progression in CADASIL, we propose an individual-based incremental training approach, with repeated learning of the segmentation algorithm from subsequent corrected data obtained along follow-up, to reduce the final manual correction time as much as possible.

Keywords: White Matter, Aging, cognitive impairment

Motivation: It is still unclear what the mechanism of the effect of white matter hyperintensities (WMHs) and cognitive impairment is.

Goal(s): To use intravoxel incoherent motion (IVIM) to evaluate the microvascular and parenchymal microstructural changes of WMHs and to investigate their association with cognitive impairment.

Approach: The IVIM parameters were compared between patients and controls, different ROIs, and different WMH severity. Additionally, a multivariate linear regression analysis was conducted to explore the factors influencing cognitive scores.

Results: WMH patients had higher parenchymal diffusivity than the control group. Furthermore, increased parenchymal diffusivity was associated with an increased risk of cognitive decline.

Impact: The IVIM technique has the potential to provide a quantitative marker of parenchymal diffusivity for assessing the severity of WMH and may be useful in quantifying cognitive dysfunction in patients with WMH.

Keywords: Infectious Disease, Spectroscopy, HIV, metabolites

Motivation: Chronic HIV infection is associated with widespread brain metabolite imbalance. However, few studies attempted to quantitate changes in brain metabolites in people with HIV (PWH) before and after initiating antiretroviral therapy (ART) treatment.

Goal(s): the aim of this study is to evaluate changes in brain metabolites in PWH, before and after initiating ART, at the whole-brain level using MRSI spectroscopic imaging (MRSI).

Approach: In this longitudinal study, changes in MRSI derived metabolite are evaluated before and after ART treatment using an atlas-based approach.

Results: Our results showed persistent neuro-inflammation in HIV subjects post-ART despite maintaining viral suppression.

Impact: This study advocates the need for continued monitoring of their brain health of PWH even after starting ART.