Characterizing White Matter Tract Organization in Polymicrogyria and Lissencephaly: A Multifiber Diffusion MRI Modeling and Tractography Study

Abstract

BACKGROUND AND PURPOSE: Polymicrogyria and lissencephaly may be associated with abnormal organization of the undelying white matter tracts that have been rarely investigated so far. Our aim was to characterize white matter tract organization in polymicrogyria and lissencephaly using constrained spherical deconvolution, a multifiber diffusion MR imaging modeling technique for white matter tractography reconstruction. MATERIALS AND METHODS:We retrospectively reviewed 50 patients (mean age, 8.3 6 5.4 years; range, 1.4-21.2 years; 27 males) with different polymicrogyria (n ¼ 42) and lissencephaly (n ¼ 8) subtypes. The fiber direction-encoded color maps and 6 different white matter tracts reconstructed from each patient were visually compared with corresponding images reconstructed from 7 agematched, healthy control WM templates. Each white matter tract was assessed by 2 experienced pediatric neuroradiologists and scored in consensus on the basis of the severity of the structural abnormality, ranging from the white matter tracts being absent to thickened. The results were summarized by different polymicrogyria and lissencephaly subgroups.RESULTS: More abnormal-appearing white matter tracts were identified in patients with lissencephaly compared with those with polymicrogyria (79.2% versus 37.3%). In lissencephaly, structural abnormalities were identified in all studied white matter tracts. In polymicrogyria, the more frequently affected white matter tracts were the cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, and optic radiation-posterior corona radiata. The severity of superior longitudinal fasciculus and cingulum abnormalities was associated with the polymicrogyria distribution and extent. A thickened superior fronto-occipital fasciculus was demonstrated in 3 patients. CONCLUSIONS:We demonstrated a range of white matter tract structural abnormalities in patients with polymicrogyria and lissencephaly. The patterns of white matter tract involvement are related to polymicrogyria and lissencephaly subgroups, distribution, and, possibly, their underlying etiologies. ABBREVIATIONS: CG ¼ cingulum; CMV ¼ cytomegalovirus; CSD ¼ constrained spherical deconvolution; DEC ¼ direction-encoded color; dMRI ¼ diffusion MRI; FOD ¼ fiber orientation distribution; HARDI ¼ high angular resolution diffusion imaging; IFOF ¼ inferior fronto-occipital fasciculus; ILF ¼ inferior longitudinal fasciculus; LIS ¼ lissencephaly; MCD ¼ malformation of cortical development; OR-PCR ¼ optic radiation-posterior corona radiata; PMG ¼ polymicrogyria; SBH ¼ subcortical band heterotopia; SFOF ¼ superior fronto-occipital fasciculus/Muratoff bundle; SLF ¼ superior longitudinal fasciculus; WMT ¼ white matter tract

Clinical and neuroimaging findings in patients with lissencephaly/subcortical band heterotopia spectrum: a magnetic resonance conventional and diffusion tensor study

“…e shows a single ventral TPF (arrow), and the CST (arrowhead) is located behind the TPF. f-k also show CST (blue fiber) running behind the dorsum of the single TPF (red fiber) patients with LIS had more white matter tract abnormalities than patients with polymicrogyria [14]. Thus, DTI enables the detection of more anomalies than conventional MRI sequences in patients with MCD, including LIS.…”

“…DTI analysis of LIS and related disorders has been reported in several studies. Arrigoni et al analyzed DTI findings of 15 patients with brainstem malformations associated with the tubulin gene family and reported that asymmetries between the two sides of the brainstem appeared to be related to asymmetries in the thickness of the major white matter tract [14]. Dobyns et al described a case of an MACF1 mutation patient who showed absence of the anterior and posterior TPF on a color map [13].…”

“…It has been known that LIS can be accompanied by a malformed brainstem [11] in the context of different entities, such as tubulinopathies [12] and lissencephaly with complex brainstem malformation linked to MACF1 pathogenic variants [13]. Recently, white matter tract abnormalities have been reported in addition to more obvious morphological abnormalities of LIS [14]. Fiber tractography by diffusion tensor imaging (DTI) can determine the distribution of nerve tracts and fiber bundles from the anisotropic motion of water [15].…”

Effects of tDCS on Language Recovery in Post-Stroke Aphasia: A Pilot Study Investigating Clinical Parameters and White Matter Change with Diffusion Imaging

“…Moreover, constrained spherical deconvolution (CSD) is better performed at higher b-value and diffusion encoding directions than those performed in the present study. Yet, CSD at b = 1000 and diffusion directions = 32 has shown to be reliable [51] and adequate to investigate white matter in clinical study [52]. This is the first preliminary pilot study to investigate WM changes underlying tDCS.…”

Diffusion MRI tractography for neurosurgery: the basics, current state, technical reliability and challenges

“…This multi-shell multi-tissue CSD technique is used growingly, providing more reliable fODF information for tractography. It is now also possible to perform reliable local multi-tissue CSD estimations using either a single-shell HARDI data (Dhollander and Connelly 2016), or a single-shell, non-HARDI dataset consisting of a lower b-value and/or lesser diffusion directions (Calamuneri et al 2018, Arrigoni et al 2020, Fekonja et al 2021. Of note, the tractography examples shown in figure 6 were reconstructed using the multi-tissue CSD model.…”