title: Rapid and automatic calculation of the midsagittal plane in magnetic resonance diffusion and perfusion images.
abstract: OBJECTIVE
  A near real-time and fully automatic method for calculation of the midsagittal plane (MSP) for magnetic resonance (MR) diffusion and perfusion images is introduced.
  
  
  METHODS
  The method is based on the Kullback-Leibler's (KL) measure quantifying the difference between two intensity distributions. The MSP is a sagittal plane with the highest KL measure. The method was validated quantitatively for 61 diffusion-weighted imaging (DWI), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), peak height (PKHT), and time to peak (TPP) data sets of 11 stroke patients based on the ground truth provided by two raters.
  
  
  RESULTS
  Average angular errors are less than 1 degrees for DWI and less than 2 degrees for CBF and CBV. Average distance errors measured in the worst case (on the brain's bounding box) are less than 2.5 mm for DWI and less than 5 mm for CBF and CBV. This algorithmic accuracy is at the level of interrater variability. Results obtained for the other perfusions maps (MTT, PKHT, TTP) were inferior; therefore, processing of CBF or CBV is preferred for accurate and robust calculation of the MSP from perfusion maps. Calculation of the MSP takes about half a second on a standard computer.
  
  
  CONCLUSIONS
  The proposed method is near real-time and fully automatic, and neither user interaction nor parameter setting is needed. It does not require preprocessing of data. The method potentially is useful in rapid and automated processing of MR stroke diffusion and perfusion images.
authors.affiliation: Biomedical Imaging Lab, Agency for Science, Technology and Research, 30 Biopolis Street, #07-01 Matrix, Singapore. wieslaw@sbic.a-star.edu.sg
authors.forename: Wieslaw L
authors.initials: WL
authors.lastname: Nowinski
authors.forename: Bhanu
authors.initials: B
authors.lastname: Prakash
authors.forename: Ihar
authors.initials: I
authors.lastname: Volkau
authors.forename: Anand
authors.initials: A
authors.lastname: Ananthasubramaniam
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Beauchamp
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D001921:Brain / Q000098:blood supply* / Q000473:pathology*; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity