Diffusion Imaging of the Congenitally Thickened Corpus Callosum

Abstract

SUMMARY:This report presents 4 subjects with congenital segmental callosal thickening, an uncommon malformation studied with MR imaging and DTI. Medical records were reviewed for genetic testing and neurodevelopmental status. Three subjects had profound developmental delay; 3 had seizures. MR imaging showed segmental thickening of the rostral and/or midcallosal body. Associated anomalies included polymicrogyria in 1 patient and optic hypoplasia in 1. DTI showed that the segmental thickening was due to anomalous longitudinal supracallosal fibers visually separable from the paired cingulum in 3 patients; in 1 patient, the cingulum was poorly formed. Genetic testing was negative for Fragile X syndrome. Microarray DNA analysis showed 3 copy losses (2q27.3, 3p21.31, 7q21.11) and 1 copy gain (8p11.23) in 1 patient, while testing in the other subject was negative for losses or gains. Potential explanations for the anomalous fibers include heterotopic cingulum, an enlarged indusium griseum, and aberrant callosal fibers. ABBREVIATIONS:FA ϭ fractional anisotropy; IG ϭ indusium griseum; M-CMTC ϭ marmorata telangiectatica congenita syndrome; NF ϭ neurofibromatosis

Spectrum of Clinical and Associated MR Imaging Findings in Children with Olfactory Anomalies

“…Diffusion tractography has been shown to be helpful in distinguishing the white matter connections within the corpus callosum, such as the presence of homo-or heterotopic fiber tracts. 36,37 This was a retrospective study with resultant limitations inherently present. We cannot infer the incidence of olfactory anomalies in the pediatric population.…”

Microstructural changes in thickened corpus callosum in children: contribution of magnetic resonance diffusion tensor imaging

“…This particular bundle has been described in association with thickened corpus callosum [3,17] but also in patients with no thickened corpus callosum [30]. Transitory corpus callosum axons have been described during development [27].…”

“…However no DTI metrics of thickened corpus callosum have been reported. Two recent papers reported that DTI and fiber tract reconstruction can show anomalous longitudinal supracallosal fibers separated from the cingulum in congenital cases of thickened corpus callosum [3,17]. One case was also analyzed histologically [17].…”

“…The pathophysiology of thickened corpus callosum is not well known because it is in some cases an isolated finding [3,4]; however it is frequently associated with other brain malformations [3,[5][6][7][8][9][10]. It can be a part of syndromic conditions such as Cohen syndrome [11], Williams syndrome [12], and neurofibromatosis type 1 [13].…”

Constrained spherical deconvolution-based tractography to depict and characterize a case of “hyperplastic fornix dorsalis”

“…In partial callosal agenesis anomalous supracallosal longitudinal WM bundles were studied by Q-Ball imaging [13]. More recently, Rollins [14] reported four patients with SLB, studied with DTI, and hypothesized these fibers might represent heterotopic cingulum, induseum griseum or aberrant callosal axons. No quantitative measurements were performed and fornix was not reconstructed.…”