PT - JOURNAL ARTICLE AU - M. Severino AU - D. Tortora AU - B. Toselli AU - S. Uccella AU - M. Traverso AU - G. Morana AU - V. Capra AU - E. Veneselli AU - M.M. Fato AU - A. Rossi TI - Structural Connectivity Analysis in Children with Segmental Callosal Agenesis AID - 10.3174/ajnr.A5043 DP - 2017 Jan 19 TA - American Journal of Neuroradiology 4099 - http://www.ajnr.org/content/early/2017/01/19/ajnr.A5043.short 4100 - http://www.ajnr.org/content/early/2017/01/19/ajnr.A5043.full AB - BACKGROUND AND PURPOSE: Segmental callosal agenesis is characterized by the absence of the intermediate callosal portion. We aimed to evaluate the structural connectivity of segmental callosal agenesis by using constrained spherical deconvolution tractography and connectome analysis.MATERIALS AND METHODS: We reviewed the clinical-radiologic features of 8 patients (5 males; mean age, 3.9 years). Spherical deconvolution and probabilistic tractography were performed on diffusion data. Structural connectivity analysis, including summary network metrics, modularity analysis, and network consistency measures, was applied in 5 patients and 10 age-/sex-matched controls.RESULTS: We identified 3 subtypes based on the position of the hippocampal commissure: beneath the anterior callosal remnant in 3 patients (type I), beneath the posterior callosal remnant in 3 patients (type II), and between the anterior and posterior callosal remnants in 2 patients (type III). In all patients, the agenetic segment corresponded to fibers projecting to the parietal lobe, and segmental Probst bundles were found at that level. Ectopic callosal bundles were identified in 3 patients. Topology analysis revealed reduced global connectivity in patients compared with controls. The network topology of segmental callosal agenesis was more variable across patients than that of the control connectomes. Modularity analysis revealed disruption of the structural core organization in the patients.CONCLUSIONS: Three malformative subtypes of segmental callosal agenesis were identified. Even the absence of a small callosal segment may impact global brain connectivity and modularity organization. The presence of ectopic callosal bundles may explain the greater interindividual variation in the connectomes of patients with segmental callosal agenesis.AbbreviationsACCagenesis of the corpus callosumHChippocampal commissurePVCpartial virtual callosotomysegACCsegmental agenesis of the corpus callosum