PMC

Quantification of myelin coverage and oligodendrocyte density following injection of IL13-MSC on the right and left sides of the splenium in CPZ-treated mice. a Upper row: representative overview images of the splenium of the corpus callosum stained for MBP (red) in control, CPZ-treated mice and CPZ-treated mice with IL13-MSC grafts. The areas which were analysed are delineated by a dotted line. Scale bar indicates 200 μm. Lower row: dot plots showing the coverage percentage of MBP over the whole splenium (left graph), the left side of the splenium (middle graph) and the right side of the splenium (right graph) for each experimental group. The mean of each group is represented by a horizontal line. Significant differences are indicated with two (p value ≤0.01) or three (p value ≤0.001) asterisks. b Upper row: representative overview images of the splenium of the corpus callosum stained for CC1⁺ oligodendrocytes (red) in control, CPZ-treated mice and CPZ-treated mice with IL13-MSC grafts. The areas which were analysed are delineated by a dotted line. Scale bar indicates 100 μm. Lower row: dot plots showing the cell density (cells/mm²) of CC1⁺ oligodendrocytes over the whole splenium (left graph), the left side of the splenium (middle graph) and the right side of the splenium (right graph) for each experimental group. The mean of each group is represented by a horizontal line. Significant differences are indicated with two (p value ≤0.01) or three (p value ≤0.001) asterisks. c Dot plots showing the correlation between MBP coverage percentage and CC1⁺ oligodendrocyte cell density (left graph), MBP coverage percentage and T ₂ relaxation times (middle graph), CC1⁺ oligodendrocyte cell density and T ₂ relaxation times (right graph) in the whole splenium for each experimental group. Spearman’s correlation coefficient (r) is presented on each graph. Data points indicated in red on (a and b) correspond with the representative MRI images provided in Fig.  and with the representative histological images shown in (a and b)

Longitudinal changes in fiber tract FA in the splenium of the corpus callosum. Superior view of acute (a) and subacute (b) fiber tracts of the splenium of the corpus callosum (CC) in a patient with good outcome (DRS = 1). Fiber tracts are color-coded according to mean FA (center inset) so that longitudinal splenium FA changes in each patient can be observed. Superior view of acute (c) and subacute (d) fiber tracts of the splenium of the CC in a patient with poor outcome (DRS = 8.5). In the patient with good outcome, splenium FA values are high in both the acute and subacute periods, as indicated by the red tract colors (solid arrows). In the subject with poor outcome, splenium FA values decline from the acute to the subacute period, as indicated by the red tracts in the acute period as compared to yellow tracts in the subacute period (dotted arrows). All tracts were reconstructed using Diffusion Toolkit version 0.6.2 and virtually dissected by manually tracing a splenium ROI in TrackVis version 5.2 (Wang & Wedeen, Athinoula A. Martinos Center for Biomedical Imaging, www.trackvis.org). Fiber tracts from the fornix and optic radiations were excluded to isolate the splenium fiber tracts. Tracts are superimposed on axial diffusion-weighted images at the level of the inferior aspect of the splenium of the CC

Axial brain MRI images of DWI, ADC, and FLAIR sequences obtained in each case. A, Case 1, early MRI (Day 3) without splenium or cortical diffusion signal. B, Repeat MRI of case 1 (Day 10), with bilateral DWI-bright and ADC-dark splenium signal. C, Case 2 (Day 7), prominent DWI-bright and ADC-dark splenium signal, with subtle cortical ribbon signal, hyperintensity of these regions also present on FLAIR sequence. D, Case 3 (Day 8), DWI-bright and ADC-dark signal in the splenium and subcortical white matter, abnormal signal not well seen on FLAIR. E, Case 4, early MRI (Day 1) with minimal pathology. F, Case 4, late MRI (Day 6) with DWI-bright and ADC-dark signal in the splenium and occipital/parietal regions, with subtle corresponding hyperintensity signal on FLAIR. G, Case 5 (Day 3), isolated ischemic lesion in the left splenium, seen on all three sequences.

Axial brain MRI images of DWI, ADC, FLAIR, T1, and T2 sequences obtained 21 days after organophosphate poisoning. A. DWI sequences showing an area of restricted diffusion in the splenium of the corpus callosum and bilateral white matters around the ventricle. B. ADC sequence, showing a corresponding dark signal area in the splenium of the corpus callosum and bilateral white matters around the ventricle. C. FLAIR sequences with bright signal intensity in the splenium of the corpus callosum with no white matters lesions. D. T1 sequences with decreased signal intensity in the splenium of the corpus callosum. E. T2 sequences with increased signal intensity in the splenium of the corpus callosum.