Focal alterations of the callosal area III in primary lateral sclerosis: An MRI planimetry and texture analysis

Highlights • The regional pattern of cerebral alterations in PLS includes the area III of the CC. • Callosal alterations of the texture parameters entropy and homogeneity were shown in PLS. • Texture and macrostructure of the callosal area III is targeted as a neuroimaging marker in PLS.
Background The regional distribution of cerebral morphological alterations in primary lateral sclerosis (PLS) is considered to include the area III of the corpus callosum (CC). Objective The study was designed to investigate regional white matter (WM) alterations in the callosal area III by T1 weighted magnetic resonance imaging (T1w-MRI) data in PLS patients compared with healthy controls, in order to identify atrophy and texture changes in vivo. Methods T1w-MRI-based white matter mapping was used to perform an operator-independent CC-segmentation for the different areas of the CC in 67 PLS patients vs 82 matched healthy controls and vs 85 ALS patients. The segmentation was followed by texture analysis of the separated CC areas for the PLS patients vs controls and vs ALS patients. Results PLS was associated with significant atrophy in the area III of the CC (but not in the other callosal segments), while the alterations in the ALS patients were much more variable and were not significant at the group level. Furthermore, significant regional alterations of the texture parameters entropy and homogeneity in this area were shown in PLS patients and in ALS patients. Conclusions This T1w-MRI study demonstrated focused regional CC atrophy and texture alterations limited to the callosal area III (which comprises fibers projecting into the primary motor cortices) in PLS, in comparison to a higher variability in CC size in ALS.