title: Robust near real-time estimation of physiological parameters from megapixel multispectral images with inverse Monte Carlo and random forest regression.
abstract: OBJECTIVE
  Multispectral imaging can provide reflectance measurements at multiple spectral bands for each image pixel. These measurements can be used for estimation of important physiological parameters, such as oxygenation, which can provide indicators for the success of surgical treatment or the presence of abnormal tissue. The goal of this work was to develop a method to estimate physiological parameters in an accurate and rapid manner suited for modern high-resolution laparoscopic images.
  
  
  METHODS
  While previous methods for oxygenation estimation are based on either simple linear methods or complex model-based approaches exclusively suited for off-line processing, we propose a new approach that combines the high accuracy of model-based approaches with the speed and robustness of modern machine learning methods. Our concept is based on training random forest regressors using reflectance spectra generated with Monte Carlo simulations.
  
  
  RESULTS
  According to extensive in silico and in vivo experiments, the method features higher accuracy and robustness than state-of-the-art online methods and is orders of magnitude faster than other nonlinear regression based methods.
  
  
  CONCLUSIONS
  Our current implementation allows for near real-time oxygenation estimation from megapixel multispectral images and is thus well suited for online tissue analysis.
authors.affiliation: Computer-Assisted Interventions, German Cancer Research Center, Heidelberg, Germany. s.wirkert@dkfz-heidelberg.de.
authors.forename: Sebastian J
authors.initials: SJ
authors.lastname: Wirkert
authors.affiliation: Department for General, Visceral and Transplantation Surgery, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Kenngott
authors.affiliation: Department for General, Visceral and Transplantation Surgery, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mayer
authors.affiliation: Department for General, Visceral and Transplantation Surgery, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mietkowski
authors.affiliation: Department for General, Visceral and Transplantation Surgery, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Department of Gastroenterology, Toxicology and Infectious Diseases, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Sauer
authors.affiliation: Hamlyn Centre for Robotic Surgery, Institute of Global Health Innovation, Imperial College London, London, UK.|Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Neil T
authors.initials: NT
authors.lastname: Clancy
authors.affiliation: Hamlyn Centre for Robotic Surgery, Institute of Global Health Innovation, Imperial College London, London, UK.|Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Elson
authors.affiliation: Computer-Assisted Interventions, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Maier-Hein
mesh_terms: D003198:Computer Simulation; D003952:Diagnostic Imaging / Q000379:methods*; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009010:Monte Carlo Method; D010100:Oxygen / Q000737:chemistry; D010101:Oxygen Consumption; D012044:Regression Analysis; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D006454:Hemoglobins; D010100:Oxygen
keywords: Anastomosis; Inverse Monte Carlo; Multispectral imaging; Oxygenation; Perfusion; Random forest; Regression