title: The chiasmatic recess of the third ventricle: delineation with magnetic resonance imaging.
abstract: OBJECTIVE
  The chiasmatic recess (CR) is a small, downward extension in the most rostral third ventricle. Few studies have highlighted its morphology. Accordingly, we explored the CR using magnetic resonance imaging.
  
  
  METHODS
  A total of 104 patients were enrolled in this study. Magnetic resonance imaging examinations were performed in axial and sagittal sections. Imaging data were obtained as thin-sliced, seamless sections.
  
  
  RESULTS
  The CR was clearly identified in 98 % of axial and 96 % of sagittal sections. The lamina terminalis was delineated as a membranous structure with homogenous thickness. The CR was consistently delineated as a smoothly tapering, cerebrospinal fluid-filled space. The number of axial images required to encompass the entire CR was 1 slice for 1.9 % of samples, 2 for 32.7 %, 3 for 49 %, 4 for 12.5 %, 5 for 1 %, and 6 for 1 %. On axial view, the CR generally presented as a long horizontal ellipse. On sagittal view, the CR showed variable shape and length. The optic chiasm-lamina terminalis angle, formed by the upper surface of the optic chiasm and inner surface of the lamina terminalis and measured on midsagittal sections, showed considerable variability.
  
  
  CONCLUSIONS
  The CR is a hollow structure with various contours. Recognition of the morphological characteristics of the CR and lamina terminalis may be helpful for safe perforation of the lamina terminalis. Magnetic resonance imaging is useful for exploring the CR.
authors.affiliation: Department of Neurological Surgery, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba, 279-0021, Japan. shotaro@juntendo-urayasu.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsutsumi
authors.affiliation: Division of Radiological Technology, Medical Satellite Yaesu Clinic, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ono
authors.affiliation: Department of Neurological Surgery, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba, 279-0021, Japan.
authors.forename: Yukimasa
authors.initials: Y
authors.lastname: Yasumoto
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D063405:Anatomic Variation; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020542:Third Ventricle / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Chiasmatic recess; Lamina terminalis; MRI; Third ventricle