title: Aberrant midsagittal fiber tracts in patients with hemimegalencephaly.
abstract: OBJECTIVE
  In hemimegalencephaly, MR imaging often reveals midsagittal bandlike structures between the 2 lateral ventricles. To determine whether these structures are aberrant midsagittal fibers, we retrospectively reviewed them on conventional MR imaging and prospectively examined them by diffusion tensor MR and fiber tract (FT) reconstruction imaging.
  
  
  METHODS
  We retrospectively reviewed conventional MR images of 26 consecutive patients with hemimegalencephaly by 2 neuroradiologists, focusing on abnormal midsagittal structures. The distance between the 2 anterior horns and widths of midsagittal bandlike structures were measured. Prospective analysis was performed in 7 consecutive patients with hemimegalencephaly examined for midsagittal aberrant fibers by diffusion tensor imaging, and cortical distribution areas of the fibers were observed.
  
  
  RESULTS
  The distance between the 2 anterior horns was wide (>4 mm) due to white matter-intensity structures in 20 of 26 patients (76.9%). Mid-sagittal bandlike structures were observed in 15 patients (57.7%). Asymmetry of the fornices was detected in 7 patients (26.9%), and both fornices were thickened in 7 (26.9%) patients. On FT reconstruction, images showed that 4 of 7 patients with hemimegalencephaly had aberrant midsagittal fibers connecting frontal, occipital, or parietal lobes, bilaterally (n = 3) or ipsilaterally (n = 1). All 4 patients had increased width between the 2 anterior horns, and 3 of them exhibited midsagittal bandlike structures on conventional MR imaging. On the other hand, these MR imaging findings were not noted in 3 patients who did not have aberrant midsagittal fibers on diffusion tensor imaging.
  
  
  CONCLUSIONS
  Aberrant midsagittal FTs running intra- or interhemispherically do not infrequently exist in patients with hemimegalencephaly.
authors.affiliation: Department of Radiology, Musashi Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan. snoriko@ncnp.go.jp
authors.forename: N
authors.initials: N
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Ota
authors.forename: A
authors.initials: A
authors.lastname: Yagishita
authors.forename: Y
authors.initials: Y
authors.lastname: Miki
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Adachi
authors.forename: Y
authors.initials: Y
authors.lastname: Nakata
authors.forename: K
authors.initials: K
authors.lastname: Sugai
authors.forename: M
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology*; D002552:Cerebral Ventricles / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003337:Corpus Callosum / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D054220:Malformations of Cortical Development / Q000473:pathology*