Identifying potential imaging markers for diffusion property changes in a mouse model of amyotrophic lateral sclerosis: Application of the continuous time random walk model to ultrahigh b-value diffusion-weighted MR images of spinal cord tissue.
Jin GaoMingchen JiangDanilo ErricoloRichard L MaginGerardo MorfiniThomas RoystonAndrew C LarsonWeiguo LiPublished in: NMR in biomedicine (2023)
Diffusion MRI (dMRI) explores tissue microstructures by analyzing diffusion-weighted signal decay measured at different b-values. While relatively low b-values are used for most dMRI models, high b-value diffusion-weighted imaging (DWI) techniques have gained interest given that the non-Gaussian water diffusion behavior observed at high b-values can yield potentially valuable information. In this study, we investigated anomalous diffusion behaviors associated with degeneration of spinal cord tissue using a continuous time random walk (CTRW) model for DWI data acquired across an extensive range of ultrahigh b-values. The diffusion data were acquired in situ from the lumbar level of spinal cords of wild-type and age-matched transgenic SOD1 G93A mice, a well-established animal model of amyotrophic lateral sclerosis (ALS) featuring progressive degeneration of axonal tracts in this tissue. Based on the diffusion decay behaviors at low and ultrahigh b-values, we applied the CTRW model using various combinations of b-values and compared diffusion metrics calculated from the CTRW model between the experimental groups. We found that diffusion-weighted signal decay curves measured with ultrahigh b-values (up to 858,022 s/mm 2 in this study) were well represented by the CTRW model. The anomalous diffusion coefficient obtained from lumbar spinal cords was significantly higher in SOD1 G93A mice compared with control mice (14.7 × 10 -5 ± 5.54 × 10 -5 vs. 7.87 × 10 -5 ± 2.48 × 10 -5 mm 2 /s, p = 0.01). We believe this is the first study to illustrate the efficacy of the CTRW model for analyzing anomalous diffusion regimes at ultrahigh b-values. The CTRW modeling of ultrahigh b-value dMRI can potentially present a novel approach for noninvasively evaluating alterations in spinal cord tissue associated with ALS pathology.
Keyphrases
- diffusion weighted
- amyotrophic lateral sclerosis
- contrast enhanced
- diffusion weighted imaging
- spinal cord
- magnetic resonance imaging
- wild type
- spinal cord injury
- computed tomography
- healthcare
- mouse model
- type diabetes
- multiple sclerosis
- neuropathic pain
- high resolution
- metabolic syndrome
- machine learning
- risk assessment
- electronic health record
- big data
- photodynamic therapy
- climate change
- convolutional neural network
- atomic force microscopy
- single molecule