title: Structural Connectivity Analysis in Children with Segmental Callosal Agenesis.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: From the Neuroradiology Unit (M.S., D.T., G.M., A.R.) mariasavinaseverino@gaslini.org.
authors.forename: M
authors.identifier: 0000-0003-4730-5322
authors.initials: M
authors.lastname: Severino
authors.affiliation: From the Neuroradiology Unit (M.S., D.T., G.M., A.R.).
authors.forename: D
authors.identifier: 0000-0002-5621-4046
authors.initials: D
authors.lastname: Tortora
authors.affiliation: Department of Informatics, Bioengineering, Robotics and System Engineering (B.T., M.M.F.), Università degli Studi di Genova Scuola Politecnica, Genoa, Italy.
authors.forename: B
authors.identifier: 0000-0001-5543-3709
authors.initials: B
authors.lastname: Toselli
authors.affiliation: Neuropsychiatry Unit (S.U., M.T., E.V.).
authors.forename: S
authors.identifier: 0000-0003-4164-2125
authors.initials: S
authors.lastname: Uccella
authors.affiliation: Neuropsychiatry Unit (S.U., M.T., E.V.).
authors.forename: M
authors.identifier: 0000-0002-8466-1003
authors.initials: M
authors.lastname: Traverso
authors.affiliation: From the Neuroradiology Unit (M.S., D.T., G.M., A.R.).
authors.forename: G
authors.identifier: 0000-0001-8707-5969
authors.initials: G
authors.lastname: Morana
authors.affiliation: Genetic Unit of the Department of Neurosurgery (V.C.), Istituto Giannina Gaslini, Genoa, Italy.
authors.forename: V
authors.identifier: 0000-0002-3097-0388
authors.initials: V
authors.lastname: Capra
authors.affiliation: Neuropsychiatry Unit (S.U., M.T., E.V.).
authors.forename: E
authors.identifier: 0000-0002-9678-2128
authors.initials: E
authors.lastname: Veneselli
authors.affiliation: Department of Informatics, Bioengineering, Robotics and System Engineering (B.T., M.M.F.), Università degli Studi di Genova Scuola Politecnica, Genoa, Italy.
authors.forename: M M
authors.identifier: 0000-0001-8085-2438
authors.initials: MM
authors.lastname: Fato
authors.affiliation: From the Neuroradiology Unit (M.S., D.T., G.M., A.R.).
authors.forename: A
authors.identifier: 0000-0001-8575-700X
authors.initials: A
authors.lastname: Rossi
mesh_terms: D000293:Adolescent; D061085:Agenesis of Corpus Callosum / Q000000981:diagnostic imaging / Q000473:pathology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D063132:Connectome; D056324:Diffusion Tensor Imaging; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D008297:Male; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000473:pathology; D012189:Retrospective Studies