Diffusion tensor MRI of the corpus callosum in amyotrophic lateral sclerosis

Abstract

Purpose To determine if decline in corpus callosum (CC) white matter integrity in patients with amyotrophic lateral sclerosis (ALS) is localized to motor-related areas. Materials and Methods Twenty-one ALS patients and 21 controls participated. Diffusion tensor images (DTI) were acquired using 3 Tesla (T) MRI. Tract-based spatial statistics were used to examine whole-brain white matter damage. A segmentation schema was used to define CC volumes-of-interest (VOI). Fractional anisotropy (FA) and radial- and axial-diffusivity (RD, AD) were extracted from VOIs and compared between groups. DTI measurements in motor-related Area III were tested for correlation with symptoms and disease duration. Results Extracted FA values from CC VOIs were reduced in ALS patients (P≤0.0001), particularly in Areas II and III (P≤0.01). Reduced FA in Area III correlated with disease symptomology (P≤0.05) and duration (P≤0.02). Between-group whole-brain comparisons (P≤0.05, corrected) showed reduced FA and increased RD throughout white matter regions including the CC, corona radiata, and internal capsule. AD was increased in the left corona radiata and internal and external capsules. Conclusion FA in motor-related regions of the CC is more affected than other CC areas in ALS patients. Microstructural pathology of transcallosal fiber tracts may represent a future component of an imaging biomarker for ALS.

Atypical Frontal–Striatal–Thalamic Circuit White Matter Development in Pediatric Obsessive-Compulsive Disorder

“…Movement artifact and eddy current distortion were corrected in FSL using standard algorithms 19, 20 applied to each of the 15 diffusion-weighted images. Field maps were used to unwarp diffusion weighted images due to echo-planar readout of the DTI sequence 21 .…”

Transcallosal connectivity of the human cortical motor network

“…Forming a bridge between the two hemispheres, it serves as a fundamental channel for interhemispheric communication, including that which mediates bimanual coordination (Brinkman 1984) and the learning of new motor skills. Degeneration of the corpus callosum is also a consistent feature of amyotrophic lateral sclerosis (ALS) (Filippini et al 2010), and the microstructural pathology of transcallosal projections within the corticomotor network provides a candidate imaging biomarker (Chapman et al 2014). While specific functional roles of the CC were first ascribed on the basis of motor deficits observed in patients with callosal lesions, and in those who had undergone partial callosotomy (Caillé et al 2005; Eliassen et al 1999, 2000; Jeeves et al 1988; Preilowski 1972), neuroimaging is now being used to infer causal relationships between transcallosal structural connectivity and interhemispheric functional connectivity (O’Reilly et al 2013).…”

White matter microstructure pathology in classic galactosemia revealed by neurite orientation dispersion and density imaging

“…In numerous diseases, reductions in FA have been found and linked to axonal degeneration (e.g. in amyotrophic lateral sclerosis, Chapman et al 2013) or myelin breakdown (e.g. in multiple sclerosis, Roosendaal et al 2009).…”