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Multiple sclerosis (MS) is an autoimmune disease involving demyelination and axonal damage in the central nervous system (CNS). In this study, we investigated pathological changes in the lumbar spinal cord of C57BL/6 mice induced with progressive experimental autoimmune encephalomyelitis (EAE) disease using 9.4-T magnetic resonance imaging (MRI). Multiparametric MRI measurements including MR spectroscopy, diffusion tensor imaging (DTI) and volumetric analyses were applied to detect metabolic changes in the CNS of EAE mice. Compared with healthy mice, EAE mice showed a significant reduction in N-acetyl aspartate and increases in choline, glycine, taurine and lactate. DTI revealed a significant reduction in fractional anisotropy and axial diffusivity and an increase in radial diffusivity in the lumbar spinal cord white matter (WM), while in the grey matter (GM), fractional anisotropy increased. High-resolution structural imaging also revealed lumbar spinal cord WM hypertrophy and GM atrophy. Importantly, these MRI changes were strongly correlated with EAE disease scoring and pathological changes in the lumbar (L2-L6), particularly WM demyelination lesions and aggregation of immune cells (microglia/macrophages and astrocytes) in this region. This study identified changes in MRI biomarker signatures that can be useful for evaluating the efficacy of novel drugs using EAE models in vivo., (© 2023 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

The main aim of this study was to employ high-resolution MRI to investigate the spatiotemporal development of pathological features associated with contusive spinal cord injury (SCI) in mice. Experimental mice were subjected to either sham surgery or moderate contusive SCI. A 16.4-T small-animal MR system was employed for nondestructive imaging of post-mortem, fixed spinal cord specimens at the subacute (7 days) and more chronic (28-35 days) stages post-injury. Routine histological techniques were used for subsequent investigation of the observed neuropathology at the microscopic level. The central core of the lesion appeared as a dark hypo-intense area on MR images at all time points investigated. Small focal hypo-intense spots were also observed spreading through the dorsal funiculi proximal and distal to the site of impact, an area that is known to undergo gliosis and Wallerian degeneration in response to injury. Histological examination revealed these hypo-intense spots to be high in iron content as determined by Prussian blue staining. Quantitative image analysis confirmed the increased presence of iron deposits at all post-injury time points investigated (p<0.05). Distant iron deposits were also detectable through live imaging without the use of contrast-enhancing agents, enabling the longitudinal investigation of this pathology in individual animals. Further immunohistochemical evaluation showed that intracellular iron deposits localised to macrophages/microglia, astrocytes and oligodendrocytes in the subacute phase of SCI, but predominantly to glial fibrillary acidic protein-positive, CC-1-positive astrocytes at later stages of recovery. Progressive, widespread intracellular iron accumulation is thus a normal feature of SCI in mice, and high-resolution MRI can be effectively used to detect and monitor these neuropathological changes with time., (Copyright © 2012 John Wiley & Sons, Ltd.)

Super-resolution reconstruction is a process by which a set of different low resolution images of the same object are used to create an enhanced, higher resolution image of that object. Recently there has been debate amongst researchers whether it is possible to obtain in-plane image enhancement using a set of low resolution magnetic resonance images, acquired by making small, independent changes to the demodulation frequency. We show that shifted low-resolution images contain different information that can be used to obtain denser sampling, leading to image enhancement. We conclude this from specific phantom experiments, applying signal processing sampling theory and taking into consideration the relative sampling of the point spread function with respect to the location of signal sources. Furthermore, the maximum achievable resolution for Fourier encoded MRI data at a boundary or object feature is governed by the effective width of the point spread function or the Fourier pixel size determined by the extent of k-space; this is verified experimentally., (Copyright © 2010 Wiley-Liss, Inc.)