title: Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences.
abstract: OBJECTIVE
  Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences.
  
  
  METHODS
  The proposed Inter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques).
  
  
  RESULTS
  The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland.
  
  
  CONCLUSIONS
  The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability.
authors: Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors: Farzad
authors: F
authors: Khalvati
authors: Aryan
authors: A
authors: Salmanpour
authors: Shahryar
authors: S
authors: Rahnamayan
authors: George
authors: G
authors: Rodrigues
authors: Hamid R
authors: HR
authors: Tizhoosh
mesh_terms: D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009929:Organ Size; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*