Tim J Adler1,2, Lynton Ardizzone3, Anant Vemuri4, Leonardo Ayala4, Janek Gröhl4,5, Thomas Kirchner4,6, Sebastian Wirkert4, Jakob Kruse3, Carsten Rother3, Ullrich Köthe3, Lena Maier-Hein4. 1. Computer Assisted Medical Interventions, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 223, 69120, Heidelberg, Germany. t.adler@dkfz-heidelberg.de. 2. Faculty of Mathematics and Computer Science, Heidelberg University, Heidelberg, Germany. t.adler@dkfz-heidelberg.de. 3. Visual Learning Lab, Heidelberg University, Heidelberg, Germany. 4. Computer Assisted Medical Interventions, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 223, 69120, Heidelberg, Germany. 5. Medical Faculty, Heidelberg University, Heidelberg, Germany. 6. Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, Germany.
Abstract
PURPOSE: Optical imaging is evolving as a key technique for advanced sensing in the operating room. Recent research has shown that machine learning algorithms can be used to address the inverse problem of converting pixel-wise multispectral reflectance measurements to underlying tissue parameters, such as oxygenation. Assessment of the specific hardware used in conjunction with such algorithms, however, has not properly addressed the possibility that the problem may be ill-posed. METHODS: We present a novel approach to the assessment of optical imaging modalities, which is sensitive to the different types of uncertainties that may occur when inferring tissue parameters. Based on the concept of invertible neural networks, our framework goes beyond point estimates and maps each multispectral measurement to a full posterior probability distribution which is capable of representing ambiguity in the solution via multiple modes. Performance metrics for a hardware setup can then be computed from the characteristics of the posteriors. RESULTS: Application of the assessment framework to the specific use case of camera selection for physiological parameter estimation yields the following insights: (1) estimation of tissue oxygenation from multispectral images is a well-posed problem, while (2) blood volume fraction may not be recovered without ambiguity. (3) In general, ambiguity may be reduced by increasing the number of spectral bands in the camera. CONCLUSION: Our method could help to optimize optical camera design in an application-specific manner.
PURPOSE: Optical imaging is evolving as a key technique for advanced sensing in the operating room. Recent research has shown that machine learning algorithms can be used to address the inverse problem of converting pixel-wise multispectral reflectance measurements to underlying tissue parameters, such as oxygenation. Assessment of the specific hardware used in conjunction with such algorithms, however, has not properly addressed the possibility that the problem may be ill-posed. METHODS: We present a novel approach to the assessment of optical imaging modalities, which is sensitive to the different types of uncertainties that may occur when inferring tissue parameters. Based on the concept of invertible neural networks, our framework goes beyond point estimates and maps each multispectral measurement to a full posterior probability distribution which is capable of representing ambiguity in the solution via multiple modes. Performance metrics for a hardware setup can then be computed from the characteristics of the posteriors. RESULTS: Application of the assessment framework to the specific use case of camera selection for physiological parameter estimation yields the following insights: (1) estimation of tissue oxygenation from multispectral images is a well-posed problem, while (2) blood volume fraction may not be recovered without ambiguity. (3) In general, ambiguity may be reduced by increasing the number of spectral bands in the camera. CONCLUSION: Our method could help to optimize optical camera design in an application-specific manner.
Keywords:
Ambiguity; Deep learning; Error analysis; Invertible neural networks; Multispectral imaging; Optical imaging; Surgical data science; Uncertainty estimation
Authors: Lena Maier-Hein; Matthias Eisenmann; Duygu Sarikaya; Keno März; Toby Collins; Anand Malpani; Johannes Fallert; Hubertus Feussner; Stamatia Giannarou; Pietro Mascagni; Hirenkumar Nakawala; Adrian Park; Carla Pugh; Danail Stoyanov; Swaroop S Vedula; Kevin Cleary; Gabor Fichtinger; Germain Forestier; Bernard Gibaud; Teodor Grantcharov; Makoto Hashizume; Doreen Heckmann-Nötzel; Hannes G Kenngott; Ron Kikinis; Lars Mündermann; Nassir Navab; Sinan Onogur; Tobias Roß; Raphael Sznitman; Russell H Taylor; Minu D Tizabi; Martin Wagner; Gregory D Hager; Thomas Neumuth; Nicolas Padoy; Justin Collins; Ines Gockel; Jan Goedeke; Daniel A Hashimoto; Luc Joyeux; Kyle Lam; Daniel R Leff; Amin Madani; Hani J Marcus; Ozanan Meireles; Alexander Seitel; Dogu Teber; Frank Ückert; Beat P Müller-Stich; Pierre Jannin; Stefanie Speidel Journal: Med Image Anal Date: 2021-11-18 Impact factor: 13.828