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BioRxiv : the Preprint Server For... Jun 2024The effects of sex, race, and Apolipoprotein E () - Alzheimer's disease (AD) risk factors - on white matter integrity are not well characterized.
INTRODUCTION
The effects of sex, race, and Apolipoprotein E () - Alzheimer's disease (AD) risk factors - on white matter integrity are not well characterized.
METHODS
Diffusion MRI data from nine well-established longitudinal cohorts of aging were free-water (FW)-corrected and harmonized. This dataset included 4,702 participants (age=73.06 ± 9.75) with 9,671 imaging sessions over time. FW and FW-corrected fractional anisotropy (FA) were used to assess differences in white matter microstructure by sex, race, and -ε4 carrier status.
RESULTS
Sex differences in FA in association and projection tracts, racial differences in FA in projection tracts, and -ε4 differences in FW limbic and occipital transcallosal tracts were most pronounced.
DISCUSSION
There are prominent differences in white matter microstructure by sex, race, and -ε4 carrier status. This work adds to our understanding of disparities in AD. Additional work to understand the etiology of these differences is warranted.
PubMed: 38915636
DOI: 10.1101/2024.06.10.598357 -
PloS One 2024With a globally aging population, there is a need to better understand how brain structure relates to function in healthy older and younger adults. (Comparative Study)
Comparative Study
OBJECTIVE
With a globally aging population, there is a need to better understand how brain structure relates to function in healthy older and younger adults.
METHODS
34 healthy participants divided into older (17; Mean = 70.9, SD = 5.4) and younger adults (17; Mean = 28.1, SD = 2.8) underwent diffusion-weighted imaging and neuropsychological assessment, including the California Verbal Learning Test 2nd Edition and the Trail Making Test (TMT-A and TMT-B). Differences in white matter microstructure for older and younger adults and the association between DTI metrics (fractional anisotropy, FA; mean diffusivity, MD) and cognitive performance were analyzed using tract-based spatial statistics (p < 0.05, corrected).
RESULTS
Older adults had significantly lower FA and higher MD than younger adults in widespread brain regions. There was a significant negative correlation between executive function (TMT-B) and MD for older adults in the right superior/anterior corona radiata and the corpus callosum. No significant relationship was detected between DTI metrics and executive function in younger adults or with memory performance in either group.
CONCLUSIONS
The findings underscore the need to examine brain-behaviour relationships as a function of age. Future studies should include comprehensive assessments in larger lifespan samples to better understand the aging brain.
Topics: Humans; White Matter; Aged; Male; Female; Adult; Neuropsychological Tests; Diffusion Tensor Imaging; Aging; Middle Aged; Executive Function; Cognition; Young Adult; Diffusion Magnetic Resonance Imaging; Brain; Aged, 80 and over; Anisotropy
PubMed: 38913655
DOI: 10.1371/journal.pone.0305818 -
Skeletal Radiology Jun 2024To explore the feasibility of simultaneous multi-slice (SMS) technique for reducing acquisition times in readout-segmented echo planar imaging (RESOLVE) for diffusion...
OBJECTIVES
To explore the feasibility of simultaneous multi-slice (SMS) technique for reducing acquisition times in readout-segmented echo planar imaging (RESOLVE) for diffusion tensor imaging (DTI) of the knee.
MATERIALS AND METHODS
A total of 30 healthy volunteers and 23 patients with knee acute injury (12 cases with anterior ligament (ACL) tears and 16 cases with patellar cartilage (PC) injury) were enrolled in this prospective study. Three DTI protocols were used: conventional RESOLVE-DTI with 12 directions (protocol 1), SMS-RESOLVE-DTI with 12 directions (protocol 2) and 20 directions (protocol 3). DTI parameters of gastrocnemius, ACL and posterior cruciate ligament (PCL), and PC from three protocols were quantitatively assessed.
RESULTS
For volunteers, protocol 2 significantly reduced acquisition time by 38.6% and 34.2% compared to protocols 1 and 3 while maintaining similar high-quality images and similar diffusive parameters, except for the fractional anisotropy (FA) and axial diffusivity (AD) of the PC between protocols 2 and 1 (P < 0.05). For injured ACL and PC, protocols 1 and 2 showed similar accurate diffusive parameters (except for AD, P = 0.025) and similar diagnostic efficacy, which demonstrated significantly lower FA and higher radial diffusivity (RD) in protocols 1 and 2 compared to volunteers (P < 0.05).
CONCLUSIONS
The 12-direction SMS-RESOLVE-DTI demonstrated a favorable balance between acquisition time and image quality, making it a promising alternative to conventional DTI for evaluating ligament and cartilage injuries.
ADVANCES IN KNOWLEDGE
The SMS technique greatly reduces acquisition time while maintaining image quality, which signified the possibility of DTI's clinical application.
PubMed: 38913177
DOI: 10.1007/s00256-024-04719-y -
Neurosurgery Jun 2024Assessment of postoperative outcomes on pediatric hydrocephalus is critical for adjusting treatment strategies. The aim of this work was to investigate the ability of...
BACKGROUND AND OBJECTIVES
Assessment of postoperative outcomes on pediatric hydrocephalus is critical for adjusting treatment strategies. The aim of this work was to investigate the ability of MRI metrics to predict postoperative outcomes.
METHODS
A total of 55 children with hydrocephalus who underwent MRI and ventriculoperitoneal shunt surgery were prospectively enrolled. MRI was also performed at 6 months postoperatively in 33 of the 55 children. A total of 92 controls matched for age and sex were enrolled and divided into preoperative and postoperative control groups. We calculated the diffusion tensor imaging along the perivascular space (DTI-ALPS) index, Evans index, and diffusion tensor imaging metrics. The ability of various metrics to predict postoperative outcomes was assessed using receiver operating characteristic curve analysis.
RESULTS
The DTI-ALPS index was significantly lower in patients with hydrocephalus than in controls. The abnormal DTI-ALPS index trended toward the normal range after surgery. Patients with lower preoperative DTI-ALPS index, lower fractional anisotropy (FA), and higher radial diffusivity in association fibers had less favorable short-term outcomes. Patients with worse long-term outcomes had lower postoperative DTI-ALPS index, higher postoperative Evans index, and lower FA and higher radial diffusivity in association fibers. Predictive performance was better when the DTI-ALPS index and FA in association fibers were used in combination than when either of these metrics was used alone.
CONCLUSION
The DTI-ALPS index and FA in association fibers provided complementary information for prognostic assessment after the ventriculoperitoneal shunt surgery on pediatric hydrocephalus. A combination of DTI-ALPS index and FA would improve our ability to predict postoperative outcomes in these patients.
PubMed: 38912801
DOI: 10.1227/neu.0000000000003050 -
Pediatric Radiology Jun 2024Magnetic resonance diffusion tensor imaging (DTI) has recently been used to evaluate the developing cartilage of children, but the influencing factors have not been well...
BACKGROUND
Magnetic resonance diffusion tensor imaging (DTI) has recently been used to evaluate the developing cartilage of children, but the influencing factors have not been well studied.
OBJECTIVE
The objective of this study was to investigate the influence of the diffusion gradient strength (b value), diffusion gradient direction, age and sex on knee cartilage DTI in healthy children aged 6-12 years.
MATERIALS AND METHODS
A total of 30 healthy child volunteers, with an average age of 8.9 ± 1.6 (mean ± standard deviation) years, were enrolled in this study. They were categorized into three groups according to their age range: 6-8 years, 8-10 years and 10-12 years, ensuring equal sex distribution in each group (5 boys and 5 girls). These volunteers underwent routine left knee joint magnetic resonance imaging (MRI) and serial DTI scans. DTI parameters were altered as follows: when b value = 600 s/mm, diffusion gradient direction was set to 6, 15, 25, 35 and 45; and when diffusion gradient direction = 25, b value was set to 300, 600, 900 and 1200 s/mm. The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were separately acquired using image post-processing techniques. The correlation between various b values, diffusion gradient directions, age and sex on the one hand and FA and ADC values on the other, was investigated.
RESULTS
(1) When diffusion gradient direction was fixed and the b value was varied, both FA and ADC exhibited a decreasing trend as the b value increased (P < 0.001). (2) When the b value was fixed and diffusion gradient direction was varied, the FA of knee cartilage showed a decreasing trend with increasing diffusion gradient direction (P < 0.001). (3) The FA value increased with age (P < 0.05).
CONCLUSION
The b value, diffusion gradient direction value and age exert a significant impact on both FA and ADC values in MR DTI of knee cartilage in children aged 6-12 years. In order to obtain a stable DTI, it is recommended to select a b value ≥ 600 s/mm and a diffusion gradient direction ≥ 25 during scanning.
PubMed: 38910223
DOI: 10.1007/s00247-024-05965-x -
Communications Biology Jun 2024Human learning varies greatly among individuals and is related to the microstructure of major white matter tracts in several learning domains, yet the impact of the...
Human learning varies greatly among individuals and is related to the microstructure of major white matter tracts in several learning domains, yet the impact of the existing microstructure of white matter tracts on future learning outcomes remains unclear. We employed a machine-learning model selection framework to evaluate whether existing microstructure might predict individual differences in learning a sensorimotor task, and further, if the mapping between tract microstructure and learning was selective for learning outcomes. We used diffusion tractography to measure the mean fractional anisotropy (FA) of white matter tracts in 60 adult participants who then practiced drawing a set of 40 unfamiliar symbols repeatedly using a digital writing tablet. We measured drawing learning as the slope of draw duration over the practice session and measured visual recognition learning for the symbols using an old/new 2-AFC task. Results demonstrated that tract microstructure selectively predicted learning outcomes, with left hemisphere pArc and SLF3 tracts predicting drawing learning and the left hemisphere MDLFspl predicting visual recognition learning. These results were replicated using repeat, held-out data and supported with complementary analyses. Results suggest that individual differences in the microstructure of human white matter tracts may be selectively related to future learning outcomes.
Topics: Humans; White Matter; Male; Female; Adult; Diffusion Tensor Imaging; Young Adult; Learning; Machine Learning; Anisotropy
PubMed: 38909103
DOI: 10.1038/s42003-024-06420-1 -
Physical Review. E May 2024We study the spectral properties of the Dirichlet-to-Neumann operator and the related Steklov problem in spheroidal domains ranging from a needle to a disk. An explicit...
We study the spectral properties of the Dirichlet-to-Neumann operator and the related Steklov problem in spheroidal domains ranging from a needle to a disk. An explicit matrix representation of this operator for both interior and exterior problems is derived. We show how the anisotropy of spheroids affects the eigenvalues and eigenfunctions of the operator. As examples of physical applications, we discuss diffusion-controlled reactions on spheroidal partially reactive targets and the statistics of encounters between the diffusing particle and the spheroidal boundary.
PubMed: 38907385
DOI: 10.1103/PhysRevE.109.055306 -
AJNR. American Journal of Neuroradiology Jun 2024Preoperative assessment of meningioma consistency is beneficial for optimizing surgical strategy and prognosis of patients. We aim to develop a non-invasive prediction...
BACKGROUND AND PURPOSE
Preoperative assessment of meningioma consistency is beneficial for optimizing surgical strategy and prognosis of patients. We aim to develop a non-invasive prediction model for meningioma consistency utilizing magnetic resonance elastography (MRE) and diffusion tensor imaging (DTI).
MATERIALS AND METHODS
Ninety-four patients (52yr ± 22, 69 females, 25 males) diagnosed with meningioma were recruited in the study. Each patient underwent preoperative T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), DTI, and MRE. Combined MRE-DTI model was developed based on multiple logistic regression. Intraoperative tumor descriptions served as clinical criteria for evaluating meningioma consistency. The diagnostic efficacy in determining meningioma consistency was evaluated using receiver operating characteristic (ROC) curve. Further validation was conducted in twenty-seven stereotactic biopsies using indentation tests and underlying mechanism was investigated by histologic analysis.
RESULTS
Among all the imaging modalities, MRE demonstrated the highest efficacy with the shear modulus magnitude (|G*|) achieving an area under the curve (AUC) of 0.81 (95% CI: 0.70-0.93). When combined with DTI, the diagnostic accuracy further increased (AUC: 0.88, 95% CI: 0.78-0.97), surpassing any modality alone. Indentation measurement based on stereotactic biopsies further demonstrated that the MRE-DTI model was suitable for predicting intra-tumor consistency. Histological analysis suggested that meningioma consistency may be correlated with tumor cell density and fibrous content.
CONCLUSIONS
The MRE-DTI combined model is effective in noninvasive prediction of meningioma consistency.
ABBREVIATIONS
MRE = magnetic resonance elastography; FA = fractional anisotropy; ROC = receiver operating characteristic; AUC = area under curve.
PubMed: 38906671
DOI: 10.3174/ajnr.A8385 -
Multiple Sclerosis and Related Disorders Jun 2024Thinning of retinal thickness seen on optical coherence tomography (OCT) is frequent in patients with neuromyelitis optica spectrum disorder (NMOSD). We explored the...
BACKGROUND
Thinning of retinal thickness seen on optical coherence tomography (OCT) is frequent in patients with neuromyelitis optica spectrum disorder (NMOSD). We explored the association between OCT metrics, MRI measurements and clinical outcomes in NMOSD.
METHODS
44 NMOSD and 60 controls underwent OCT and MR imaging. Mean peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell complex (GCC) thicknesses were measured. Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) was used to measure the white matter microstructural integrity. In NMOSD patients, Expanded Disability Status Scale (EDSS) was used to quantify disability. Visual acuity (VA) was also performed for all participants.
RESULTS
pRNFL thickness was positively associated with mean diffusivity in left posterior thalamic radiation (pp = 0.010) and axial kurtosis in inferior cerebellar peduncle (p = 0.023). Similarly, GCC thickness in NMOSD patients was positively associated with fractional anisotropy in right superior longitudinal fascicules (p = 0. 041) and axial kurtosis of left cerebellar peduncle (p = 0.011).
CONCLUSIONS
In NMOSD, pRNFL and GCC reflect integrity of clinically relevant white matter structures underlying the value of OCT metrics as markers of neuronaxonal loss and disability.
PubMed: 38905991
DOI: 10.1016/j.msard.2024.105713 -
Journal of Neurosurgery. Spine Jun 2024Cervical spondylotic myelopathy (CSM) stands as the most prevalent form of spinal cord injury, frequently prompting various changes in both the brain and spinal cord....
OBJECTIVE
Cervical spondylotic myelopathy (CSM) stands as the most prevalent form of spinal cord injury, frequently prompting various changes in both the brain and spinal cord. However, the precise nature of these changes within the brains and spinal cords of CSM patients experiencing hand clumsiness (HCL) symptoms has remained elusive. The authors aimed to scrutinize these alterations and explore potential links between these changes and the onset of HCL symptoms.
METHODS
Using the modified Japanese Orthopaedic Association (mJOA) scale, the authors classified CSM patients into two groups: those without HCL and those with HCL. The authors performed voxel-wise z-score transformation amplitude of low-frequency fluctuations (zALFF) and resting-state functional connectivity (FC) evaluations in the brain. Additionally, they used the Spinal Cord Toolbox to calculate the fractional anisotropy (FA) of spinal cord tracts. The analysis also encompassed an examination of the correlation of these measures with improvements in mJOA scores.
RESULTS
Significant disparities in zALFF values surfaced in the right calcarine, right cuneus, right precuneus, right middle occipital gyrus (MOG), right superior occipital gyrus (SOG), and right superior parietal gyrus (SPG) between healthy controls (HC), patients without HCL, and patients with HCL, primarily within the visual cortex. In the patient group, patients with HCL displayed reduced FC between the right calcarine, right MOG, right SOG, right SPG, right SFG, bilateral MFG, and left median cingulate and paracingulate gyri when compared with patients without HCL. Moreover, significant differences in FA values of the corticospinal tract (CST) and reticulospinal tract (REST) at the C2 level emerged among HC, patients without HCL, and patients with HCL. Notably, zALFF, FC, and FA values in specific brain regions and spinal cord tracts exhibited correlations with mJOA upper-extremity scores. Additionally, FA values of the CST and REST correlated with zALFF values in the right calcarine, right MOG, right SOG, and right SPG.
CONCLUSIONS
Alterations within brain regions associated with the visual cortex, the fronto-parietal-occipital attention network, and spinal cord pathways appear to play a substantial role in the emergence and progression of HCL symptoms. Furthermore, the existence of a potential connection between the spinal cord and the brain suggests that this link might be related to the clinical symptoms of CSM.
PubMed: 38905708
DOI: 10.3171/2024.4.SPINE231238