Tract-Based Analysis of Callosal, Projection, and Association Pathways in Pediatric Patients with Multiple Sclerosis: A Preliminary Study

Abstract

Increased mean ADC and decreased mean FA occur in all 3 major white matter pathways, both in visibly involved white matter and NAWM in pediatric MS.

Diffusion Tensor Analysis of Pediatric Multiple Sclerosis and Clinically Isolated Syndromes

“…We found significantly increased mean ADC and decreased mean FA in all white matter pathways assessed containing lesioned and nonlesioned tracts and NAWM containing nonlesioned tracts of pediatric patients with MS. Similar to findings in adult MS studies [21][22][23] and our previous study in pediatric MS, 9 diffusion abnormalities were again noted in the callosal fibers, projection fibers, and association fiber pathways in pediatric patients with MS in our separate and unique cohort. We did not find significant involvement of these structures in the MCIS and PCISWOE groups.…”

“…These findings occurred both in tracts with visibly involved focal lesions and in NAWM defined as tracts without discernible focal lesions, 9 indicating that pathologic processes in pediatric MS diffusely involve the white matter.…”

“…Reconstructed data were converted into tracts by using the standard fiber assignment by continuous tracking 14 algorithm with an angle threshold set at 35°. As in our previous study, 9 we used a DWI mask to remove CSF but did not use an FA threshold for tract reconstruction because the standard FA threshold of 0.2 would drop out tracts passing through some lesions and bias our results. Region-of-interest placement [15][16][17] and fiber tract data analysis [15][16][17] were performed on Track-Vis (www.trackvis.org).…”

“…9 These ROIs were placed in the genu, anterior midbody, posterior midbody, and splenium of the corpus callosum; PLIC, cerebral peduncle; in the anatomic region to segment the superior longitudinal fascicle; and in the region at the level of anterior floor of the external capsule to segment the inferior fronto-occipital fascicle and uncinate fascicle. Tracts intersecting these ROIs were constructed.…”

“…Region-of-interest placement [15][16][17] and fiber tract data analysis [15][16][17] were performed on Track-Vis (www.trackvis.org). 9 The seed points were placed, manually defining a region of interest by referring to standard color FA maps cross-referenced with b ϭ 0 T2-weighted images and a tractography atlas for accurate placement. [18][19][20] A single region of interest was placed in the entire corpus callosum in the midsagittal plane for the interhemispheric fiber pathway.…”