Abstract
Purpose
Rapid evaporative ionization mass spectrometry (REIMS) is an emerging technology for clinical margin detection. Deployment of REIMS depends on construction of reliable deep learning models that can categorize tissue according to its metabolomic signature. Challenges associated with developing these models include the presence of noise during data acquisition and the variance in tissue signatures between patients. In this study, we propose integration of uncertainty estimation in deep models to factor predictive confidence into margin detection in cancer surgery.
Methods
iKnife is used to collect 693 spectra of cancer and healthy samples acquired from 91 patients during basal cell carcinoma resection. A Bayesian neural network and two baseline models are trained on these data to perform classification as well as uncertainty estimation. The samples with high estimated uncertainty are then removed, and new models are trained using the clean data. The performance of proposed and baseline models, with different ratios of filtered data, is then compared.
Results
The data filtering does not improve the performance of the baseline models as they cannot provide reliable estimations of uncertainty. In comparison, the proposed model demonstrates a statistically significant improvement in average balanced accuracy (75.2%), sensitivity (74.1%) and AUC (82.1%) after removing uncertain training samples. We also demonstrate that if highly uncertain samples are predicted and removed from the test data, sensitivity further improves to 88.2%.
Conclusions
This is the first study that applies uncertainty estimation to inform model training and deployment for tissue recognition in cancer surgery. Uncertainty estimation is leveraged in two ways: by factoring a measure of input noise in training the models and by including predictive confidence in reporting the outputs. We empirically show that considering uncertainty for model development can help improve the overall accuracy of a margin detection system using REIMS.






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Funding
We would like to thank the following sources of funding: Natural Sciences and Engineering Council of Canada (NSERC), the Canadian Institute for Health Research (CIHR), Southeastern Ontario Academic Medical Organization (SEAMO) Innovation Fund, Britton Smith Chair in Surgery to J. Rudan, and Canada Research Chair to G. Fichtinger.
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This study was approved by the Queen’s University Health Sciences Research Ethics Board.
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Fooladgar, F., Jamzad, A., Connolly, L. et al. Uncertainty estimation for margin detection in cancer surgery using mass spectrometry. Int J CARS 17, 2305–2313 (2022). https://doi.org/10.1007/s11548-022-02764-3
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DOI: https://doi.org/10.1007/s11548-022-02764-3