Abstract
BackgroundNeocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS), but their visualization by magnetic resonance imaging (MRI) remains challenging.ObjectivesWe aimed at assessing the sensitivity of multi echo gradient echo (ME-GRE) T2 *-weighted MRI at 7.0 Tesla in depicting NLs compared to myelin and iron staining.MethodsSamples from two MS patients were imaged post mortem using a whole body 7T MRI scanner with a 24-channel receive-only array. Isotropic 200 micron resolution images with varying T2 * weighting were reconstructed from the ME-GRE data and converted into R2 * maps. Immunohistochemical staining for myelin (proteolipid protein, PLP) and diaminobenzidine-enhanced Turnbull blue staining for iron were performed.ResultsProspective and retrospective sensitivities of MRI for the detection of NLs were 48% and 67% respectively. We observed MRI maps detecting only a small portion of 20 subpial NLs extending over large cortical areas on PLP stainings. No MRI signal changes suggestive of iron accumulation in NLs were observed. Conversely, R2 * maps indicated iron loss in NLs, which was confirmed by histological quantification.ConclusionsHigh-resolution post mortem imaging using R2 * and magnitude maps permits detection of focal NLs. However, disclosing extensive subpial demyelination with MRI remains challenging.
Highlights
Neocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS) [1]
NLs may be present at any stage of the disease, widespread cortical demyelination is a typical feature of progressive MS [2]
According to the classification of NLs by Peterson and colleagues [3], subpial demyelinating NLs that spread from the pial surface with variable depth into the cortex, or type III NLs, constitute the most common manifestation of NLs observed with histopathology
Summary
Neocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS) [1]. NLs may be present at any stage of the disease, widespread cortical demyelination is a typical feature of progressive MS [2]. The identification of NLs in brains of MS patients using magnetic resonance imaging (MRI) is challenging both in vivo and post mortem. T2*-weighted (T2*-w) ME-GRE images and reconstructed R2* and phase maps at 7T may reveal detailed structures in various brain regions [5,6,7,8], including cortical laminae in grey matter (GM) as well as fiber bundles in white matter (WM) and cortex [6,8]. Neocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS), but their visualization by magnetic resonance imaging (MRI) remains challenging
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