Alterations in white matter (WM) microstructure of the central nervous system have been shown to be pathophysiological presentations of various neurodegenerative disorders. Current methods for measuring such WM features require ex vivo tissue samples analyzed using electron microscopy. Magnetic Resonance Imaging (MRI) diffusion-weighted pulse sequences provide a non-invasive tool for estimating such microstructural features in vivo. The current project investigated the use of two methods of analysis, including the ROI-based (Region of Interest, RBA) and voxel-based analysis (VBA), as well as four mathematical models of WM microstructure, including the ActiveAx Frequency-Independent Extra-Axonal Diffusion (AAI), ActiveAx Frequency-Dependent Extra-Axonal Diffusion (AAD), AxCaliber Frequency-Independent Extra-Axonal Diffusion (ACI), and AxCaliber Frequency-Dependent Extra-Axonal Diffusion (ACD) models. Two mice samples imaged at 7 T and 15.2 T were analyzed. Both the AAI and AAD models provide a single value for each of the fit parameters, including mean effective axon diameter AxD¯, packing fraction f, intra-cellular and D and extra-cellular D diffusion coefficients, as well as the frequency dependence of D, β for the AAD model. The ACI and ACD models provide this, in addition to a distribution of axon diameters for a chosen ROI. VBA extends this, providing a parameter value for each voxel within the selected ROI, at the cost of increased computational load and analysis time. Overall, RBA-ACD and VBA-AAD were found to be optimal for parameter fitting to physically relevant values in a reasonable time frame. A full comparison of each combination of RBA and VBA with AAI, AAD, ACI, and ACD is provided to give the reader sufficient information to make an informed decision of which model is best for their own experiments.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/j.mri.2024.110221 | DOI Listing |
Zh Nevrol Psikhiatr Im S S Korsakova
December 2024
Federal Center of Brain Research and Neurotechnologies, Moscow, Russia.
Objective: To study microstructural abnormalities in epileptogenic focus and in mirror region by diffusion kurtosis (DK) MRI in patients with focal temporal lobe epilepsy.
Material And Methods: The main group included 12 patients (mean age 35 [30.5; 39.
Magn Reson Imaging
January 2025
Department of Physics, University of Winnipeg, Winnipeg, MB, Canada. Electronic address:
Degeneration of white matter (WM) microstructure in the central nervous system is characteristic of many neurodegenerative conditions. Previous research indicates that axonal degeneration visible in ex vivo electron microscopy (EM) photomicrographs precede the onset of clinical symptoms. Measuring WM microstructural features, such as axon diameter and packing fraction, currently require these highly invasive methods of analysis and it is therefore of great importance to develop methods for in vivo measurements.
View Article and Find Full Text PDFCancer Imaging
October 2024
Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, PR China.
Background: Recurrence of lower grade glioma (LrGG) appeared to be unavoidable despite considerable research performed in last decades. Thus, we evaluated the postoperative recurrence within two years after the surgery in patients with LrGG by preoperative advanced diffusion magnetic resonance imaging (dMRI).
Materials And Methods: 48 patients with lower-grade gliomas (23 recurrence, 25 nonrecurrence) were recruited into this study.
Magn Reson Imaging
November 2024
Department of Physics, University of Winnipeg, Winnipeg, MB, Canada. Electronic address:
bioRxiv
July 2024
Department of Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.
Background: Multiple studies point to the role of neuroinflammation in the pathophysiology of schizophrenia (SCZ), however, there have been few tools for imaging brain inflammation. Diffusion basis spectrum imaging (DBSI) is an advanced diffusion-based MRI method developed to quantitatively assess microstructural alternations relating to neuroinflammation, axonal fiber, and other white matter (WM) pathologies.
Methods: We acquired one-hour-long high-directional diffusion MRI data from young control (CON, = 27), schizophrenia (SCZ, = 21), and bipolar disorder (BPD, = 21) participants aged 18-30.
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!