DTI
Diffusion Tensor Imaging & Tractography (dMRI / NODDI)
拡散テンソル画像・拡散MRIトラクトグラフィー（DTI / NODDI）
1. Biological & Technical Mechanism
Diffusion MRI (dMRI) and Diffusion Tensor Imaging (DTI) model the three-dimensional diffusion of water molecules constrained by axonal membranes and myelin sheaths. Key derived metrics include Fractional Anisotropy (FA, reflecting directional coherence), Mean Diffusivity (MD), Axial Diffusivity (AD, sensitive to axonal injury), and Radial Diffusivity (RD, sensitive to demyelination). Multi-shell protocols enable Neurite Orientation Dispersion and Density Imaging (NODDI).
拡散テンソル画像（DTI）および拡散MRI（dMRI）は、軸索膜や髄鞘（ミエリン）によって制限される水分子のブラウン運動の方向依存性（異方性）を計測する手法です。異方性比率（FA: Fractional Anisotropy）、平均拡散能（MD）、軸索損傷を反映する軸方向拡散能（AD）、脱髄を反映する動径方向拡散能（RD）などの定量値に加え、マルチシェル撮像による神経突起密度イメージング（NODDI）や全脳白質トラクトグラフィーが可能です。
2. Open Science & Clinical Trial Significance
DTI is critical for quantifying corticospinal tract degeneration in ALS, corpus callosum and normal-appearing white matter damage in Multiple Sclerosis, and nigrostriatal pathway alterations in Parkinson's disease.
ALSにおける錐体路（皮質脊髄路）の変性評価、多発性硬化症（MS）における一見正常に見える白質（NAWM）の微細脱髄損傷の検出、およびアルツハイマー病・FTDにおける連合線維束の離断解析に広く活用されています。
Related Neuroscience Terms & Standards
Non-invasive neuroimaging modality measuring blood-oxygen-level-dependent (BOLD) hemodynamic signals to map brain network activity and functional connectivity.
Axonal cytoskeletal protein released into CSF and blood upon neuroaxonal injury; a cross-disease biomarker of neurodegeneration rate in ALS, MS, AD, and FTD.
Community ISO-aligned standard for organizing and describing neuroimaging (MRI, fMRI, dMRI, PET) and neurophysiological (EEG, MEG, iEEG) datasets.
Chronic white matter MS lesions bordered by a dense rim of iron-laden, proinflammatory activated microglia/macrophages, visible on T2* phase MRI, SWI, and QSM.
MRI finding showing a small thin vein running centrally through a white matter hyperintense lesion on T2*-weighted / FLAIR* imaging, reflecting the perivenular pathology of Multiple Sclerosis.
Standard 0.0–10.0 ordinal clinical rating scale quantifying neurological disability across 8 functional systems and ambulation capacity in Multiple Sclerosis.
Open Datasets & Research Publications Related to DTI
The microstructure-weighted human connectome: network properties and structure-function correlations across spatial scales
Conventional connectome edge weights, such as number of streamlines (NOS) or diffusion tensor imaging (DTI) metrics, lack specificity to microstructural details which may hold relevance for macroscale brain organisation. Since biophysical diffusion modelling offers greater specificity to microstruct...
OpenNeuro ds008755: Mouse Cocaine Self-Administration Withdrawal DTI
BIDS neuroimaging dataset containing MRI scans from 4 Subjects. Freely available for computational neuroscience.
OpenNeuro BIDS Repository: 3T/7T 3D-FLAIR, MP2RAGE & Quantitative Susceptibility Mapping (QSM) of Paramagnetic Rim Lesions in Multiple Sclerosis
High-resolution structural MRI, T2*-weighted phase/QSM, and multi-shell diffusion tensor imaging (DTI) dataset with manual expert lesion masks for white matter lesions, paramagnetic rim lesions (PRLs), and central vein sign (CVS) assessment.
MSDA: COVID19 GDSI LocalDashboard - Federated MS Data Toolkit
Official open-source repository and tool for Multiple Sclerosis federated research and data harmonization under MS-DATA-ALLIANCE.
Global Data Sharing Initiative (GDSI): Containerized Federated Analysis Pipeline for MS Registries
International federated research initiative and containerized query framework allowing participating national MS registries to analyze disease-modifying therapy (DMT) safety, anti-CD20 outcomes, and PIRA progression without transferring identifiable patient data.
Multiple Sclerosis and Viruses: « Liaisons Dangereuses ».
Multiple sclerosis (MS) is a complex, multifactorial neurodegenerative disease with an aetiology that is still partially elusive. Several risk factors are associated with MS development including genetic predisposition and various environmental stressors; however, recently, viral infections have gained significant attention as a crucial environmental trigger. Despite the well-established link between Epstein-Barr virus (EBV) and MS susceptibility, a single-pathogen model fails to clearly characterise the molecular cascades driving the disease, suggesting that the transition from infection to autoimmune response involves more than one viral agent. In this review we examine the speculation that the interactions among different neurotropic viruses could serve a collective causative role in MS, which is under-researched in the literature at present. We summarise contradictory evidence on the role of different viral agents, including the Herpesviridae family (Human Cytomegalovirus, EBV, Herpes Simplex Viruses HSV-1 and HSV-2, and Varicella Zoster Virus), Paramyxoviridae family (Measles Virus and Rubella Virus), Influenza virus, SARS-CoV-2, and Human Endogenous Retroviruses (HERVs). Through interplay within shared molecular pathways, immune modulation, and activation of latent infections, these viruses may collectively influence the inflammatory and demyelinating processes that characterise MS. This review evaluates the etiological role of viral interplay in MS through the cumulative and interactive effects of these pathogens. The available epidemiological, immunological, and experimental data converge on the concept that viral co-exposures act synergistically to shape MS susceptibility in genetically predisposed individuals. Characterising these viral interactions presents a new research direction for the identification of novel biomarkers and the development of preventative strategies through the targeted control of viral networks.
Disclaimer: This encyclopedia entry is intended for academic neuroscience research and data science reference only, and does not constitute medical advice.