title: Size versus shape differences: contrasting voxel-based and volumetric analyses of the anterior cingulate cortex in individuals with acute posttraumatic stress disorder.
abstract: BACKGROUND
  Two studies found morphological differences in the anterior cingulate cortex (ACC) of individuals with chronic posttraumatic stress disorder (PTSD). We sought to replicate and extend these findings in a sample of individuals with acute PTSD.
  
  
  METHODS
  The ACCs of individuals with acute PTSD (n = 14) and matched healthy control subjects (n = 14) were compared using voxel-based morphometry (VBM), semi-automated volumetric analyses, and probabilistic maps. Posttraumatic stress disorder diagnosis was ascertained by a psychologist using a structured interview.
  
  
  RESULTS
  Voxel-based morphometry analyses revealed significantly less gray-matter density in the right pregenual ACC and in the left insula of the PTSD group. However, volumetric analyses of the ACC revealed no significant differences between groups. Probabilistic maps of the labels of the pregenual ACC indicated that the difference between groups in gray matter density was due to shape differences.
  
  
  CONCLUSIONS
  Although there are no volumetric differences in the ACC of acute PTSD individuals compared with normal control subjects, significant shape differences exist, which might indicate volumetric differences in the surrounding structures.
authors.affiliation: Douglas Hospital Research Center, Department of Psychiatry, Montreal, Quebec, Canada. vincent.corbo@douglas.mcgill.ca
authors.forename: Vincent
authors.initials: V
authors.lastname: Corbo
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Clément
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Armony
authors.forename: Jens C
authors.initials: JC
authors.lastname: Pruessner
authors.forename: Alain
authors.initials: A
authors.lastname: Brunet
mesh_terms: D000063:Accidents, Traffic / Q000523:psychology; D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology* / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012016:Reference Values; D018709:Statistics, Nonparametric; D013313:Stress Disorders, Post-Traumatic / Q000473:pathology* / Q000503:physiopathology