title: Anterior commissure--posterior commissure revisited.
abstract: OBJECTIVE
  The anterior commissure (AC) and posterior commissure (PC) are the two distinct anatomic structures in the brain which are difficult to observe in detail with conventional MRI, such as a 1.5T MRI system. However, recent advances in ultra-high resolution MRI have enabled us to examine the AC and PC directly. The objective of the present study is to standardize the shape and size of the AC and PC using a 7.0T MRI and to propose a new brain reference line.
  
  
  METHODS
  Thirty-four, 21 males and 13 females, healthy volunteers were enrolled in this study. After determining the center of each AC and PC, we defined the connection of these centers as the central intercommissural line (CIL). We compared the known extra- and intra-cerebral reference lines with the CIL to determine the difference in the angles. Additionally, we obtained horizontal line from flat ground line of look front human.
  
  
  RESULTS
  The difference in angle of the CIL and the tangential intercommissural line (TIL) from the horizontal line was 8.7 ± 5.1 (11 ± 4.8) and 17.4 ± 5.2 (19.8 ± 4.8) degrees in males and females, respectively. The difference in angle between the CIL and canthomeatal line was 10.1 in both male and female, and there was no difference between both sexes. Likewise, there was no significant difference in angle between the CIL and TIL between both sexes (8.3 +/- 1.1 in male and 8.8 +/- 0.7 in female).
  
  
  CONCLUSIONS
  In this study, we have used 7.0T MRI to define the AC and PC quantitatively and in a more robust manner. We have showed that the CIL is a reproducible reference line and serves as a standard for the axial images of the human brain.
authors.affiliation: Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon 405-760, Korea.
authors.forename: Sang-Han
authors.initials: SH
authors.lastname: Choi
authors.forename: Je-Geun
authors.initials: JG
authors.lastname: Chi
authors.forename: Young-Bo
authors.initials: YB
authors.lastname: Kim
authors.forename: Zang-Hee
authors.initials: ZH
authors.lastname: Cho
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Anterior commissure; Brain reference; Canthomeatal line; Central intercommissural line; Posterior commissure; Tangential intercommissureal line
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