title: A comparison of the accuracy of statistical models of prostate motion trained using data from biomechanical simulations.
abstract: Statistical shape models (SSM) are widely used in medical image analysis to represent variability in organ shape. However, representing subject-specific soft-tissue motion using this technique is problematic for applications where imaging organ changes in an individual is not possible or impractical. One solution is to synthesise training data by using biomechanical modelling. However, for many clinical applications, generating a biomechanical model of the organ(s) of interest is a non-trivial task that requires a significant amount of user-interaction to segment an image and create a finite element mesh. In this study, we investigate the impact of reducing the effort required to generate SSMs and the accuracy with which such models can predict tissue displacements within the prostate gland due to transrectal ultrasound probe pressure. In this approach, the finite element mesh is based on a simplified geometric representation of the organs. For example, the pelvic bone is represented by planar surfaces, or the number of distinct tissue compartments is reduced. Such representations are much easier to generate from images than a geometrically accurate mesh. The difference in the median root-mean-square displacement error between different SSMs of prostate was <0.2 mm. We conclude that reducing the geometric complexity of the training model in this way made little difference to the absolute accuracy of SSMs to recover tissue displacements. The implication is that SSMs of organ motion based on simulated training data may be generated using simplified geometric representations, which are much more compatible with the time constraints of clinical workflows.
authors.affiliation: Centre for Medical Image Computing, Department of Medical Physics and Bioengineering, University College London, London, UK. yipeng.hu@ucl.ac.uk
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Hu
authors.forename: Rieneke
authors.initials: R
authors.lastname: van den Boom
authors.forename: Timothy
authors.initials: T
authors.lastname: Carter
authors.forename: Zeike
authors.initials: Z
authors.lastname: Taylor
authors.forename: David
authors.initials: D
authors.lastname: Hawkes
authors.forename: Hashim Uddin
authors.initials: HU
authors.lastname: Ahmed
authors.forename: Mark
authors.initials: M
authors.lastname: Emberton
authors.forename: Clare
authors.initials: C
authors.lastname: Allen
authors.forename: Dean
authors.initials: D
authors.lastname: Barratt
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D006801:Humans; D008297:Male; D015233:Models, Statistical; D009038:Motion; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology / Q000502:physiology*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity