title: MRI-based large deformation high dimensional mapping of the hippocampus in rats: development and validation of the technique.
abstract: OBJECTIVE
  To report the detection of structural and functional biological changes in living animals using small animal in vivo MRI that complements traditional ex vivo histological techniques. We report the development and validation of the application of large deformation high dimensional mapping (HDM-LD) segmentation for the hippocampus in the rat.
  
  
  METHODS
  High resolution volumetric T2 weighted MRI images were acquired at 4.7 Tesla from six male in-breed nonepileptic Wistar rats. Two HDM-LD segmentations of the hippocampus (automated 1 and automated 2) were compared with the manual segmentations of two investigators who independently segmented the hippocampi (manual 1 and manual 2).
  
  
  RESULTS
  The mean overlap for the hippocampi between automated 1 and automated 2 for the right hippocampi was 94.4% (SD 1.0) and for the left hippocampi was 94.3% (SD 2.5), while the mean overlap between automated 1 and manual 1 for the right hippocampi was 91.4% (SD 1.3) and for the left hippocampi was 91.9% (SD 1.4). Mean values for absolute differences for comparisons of all the segmentations were the following: automated 1 versus automated 2, 3.2% (SD 1.0); manual 1 versus manual 2 6.82% (SD 5.22); automated 1 versus manual 1 13.0% (SD 1.8).
  
  
  CONCLUSIONS
  HDM-LD can be applied to obtain accurate and reproducible three-dimensional segmentations of the hippocampus from rat MR images. HDM-LD will be a useful tool for investigations of hippocampal structural changes in vivo in rat models of human disease.
authors.affiliation: The Department of Neurology, Washington University, St. Louis, Missouri 63110, USA. hogan@wustl.edu
authors.forename: R Edward
authors.initials: RE
authors.lastname: Hogan
authors.forename: Viviane
authors.initials: V
authors.lastname: Bouilleret
authors.forename: Ying Rui
authors.initials: YR
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: John P
authors.initials: JP
authors.lastname: Williams
authors.forename: Bianca
authors.initials: B
authors.lastname: Jupp
authors.forename: Damian
authors.initials: D
authors.lastname: Myers
authors.forename: Terence J
authors.initials: TJ
authors.lastname: O'Brien
mesh_terms: D000375:Aging / Q000473:pathology*; D000465:Algorithms; D000818:Animals; D006624:Hippocampus / Q000033:anatomy & histology*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity