title: Automated breast segmentation of fat and water MR images using dynamic programming.
abstract: OBJECTIVE
  To develop and test an algorithm that outlines the breast boundaries using information from fat and water magnetic resonance images.
  
  
  METHODS
  Three algorithms were implemented and tested using registered fat and water magnetic resonance images. Two of the segmentation algorithms are simple extensions of the techniques used for contrast-enhanced images: one algorithm uses clustering and local gradient (CLG) analysis and the other algorithm uses a Hessian-based sheetness filter (HSF). The third segmentation algorithm uses k-means++ and dynamic programming (KDP) for finding the breast pixels. All three algorithms separate the left and right breasts using either a fixed region or a morphological method. The performance is quantified using a mutual overlap (Dice) metric and a pectoral muscle boundary error. The algorithms are evaluated against three manual tracers using 266 breast images from 14 female subjects.
  
  
  RESULTS
  The KDP algorithm has a mean overlap percentage improvement that is statistically significant relative to the HSF and CLG algorithms. When using a fixed region to remove the tissue between breasts with tracer 1 as a reference, the KDP algorithm has a mean overlap of 0.922 compared to 0.864 (P < .01) for HSF and 0.843 (P < .01) for CLG. The performance of KDP is very similar to tracers 2 (0.926 overlap) and 3 (0.929 overlap). The performance analysis in terms of pectoral muscle boundary error showed that the fraction of the muscle boundary within three pixels of reference tracer 1 is 0.87 using KDP compared to 0.578 for HSF and 0.617 for CLG. Our results show that the performance of the KDP algorithm is independent of breast density.
  
  
  CONCLUSIONS
  We developed a new automated segmentation algorithm (KDP) to isolate breast tissue from magnetic resonance fat and water images. KDP outperforms the other techniques that focus on local analysis (CLG and HSF) and yields a performance similar to human tracers.
authors.affiliation: Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721.
authors.forename: José A
authors.initials: JA
authors.lastname: Rosado-Toro
authors.affiliation: Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85721.
authors.forename: Tomoe
authors.initials: T
authors.lastname: Barr
authors.affiliation: Department of Medical Imaging, University of Arizona, Tucson, AZ 85724.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Galons
authors.affiliation: Arizona Cancer Center, Tucson, Arizona 85721.
authors.forename: Marilyn T
authors.initials: MT
authors.lastname: Marron
authors.affiliation: Arizona Cancer Center, Tucson, Arizona 85721; Department of Medicine, University of Arizona, Tucson, Arizona 85724.
authors.forename: Alison
authors.initials: A
authors.lastname: Stopeck
authors.affiliation: Arizona Cancer Center, Tucson, Arizona 85721.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Thomson
authors.affiliation: Arizona Cancer Center, Tucson, Arizona 85721; Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85721.
authors.forename: Patricia
authors.initials: P
authors.lastname: Thompson
authors.affiliation: Department of Medical Imaging, University of Arizona, Tucson, AZ 85724.
authors.forename: Danielle
authors.initials: D
authors.lastname: Carroll
authors.affiliation: Department of Medical Imaging, University of Arizona, Tucson, AZ 85724.
authors.forename: Eszter
authors.initials: E
authors.lastname: Wolf
authors.affiliation: Department of Medical Imaging, University of Arizona, Tucson, AZ 85724. Electronic address: maltbach@radiology.arizona.edu.
authors.forename: María I
authors.initials: MI
authors.lastname: Altbach
authors.affiliation: Department of Electrical and Computer Engineering, University of Arizona, Tucson, Arizona 85721.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Rodríguez
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000465:Algorithms; D001834:Body Water; D001940:Breast; D001943:Breast Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods; D011382:Programming, Linear; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
keywords: Automated breast segmentation; breast MRI; dynamic programming; fat-water MRI; k-means++