While software using artificial intelligence and machine learning (AI/ML) is pervasive in many areas of society today, the use of these technologies to diagnose and treat medical conditions is limited due to a number of challenges associated with the trustworthiness of the results. This may include the inability to fully explain how an algorithm works inherent to the black-box nature of the system. Additionally, AI/ML may create a potential for bias and artifacts that cannot be validated due to the same limitations. In a medical application, the lack of transparency in how the system operates may lead to a loss of trust by users. Bayesian approaches that use computational modeling to quantify the level of uncertainty in a given result may provide a path towards improved confidence and use. In this paper, evidence from studies in a range of medical applications is presented and discussed, showing how Bayesian approaches can help to foster trust. A retrospective study using a publicly available dataset explored the feasibility of creating predictive models for early intervention in a Type 1 diabetes population. Creating the perfect model was not the goal of the exercise, rather the study aimed to demonstrate how Bayesian methods could be used to identify areas of uncertainty during model development. Feature selection was based on analytical assessment of various patterns found in the data. Models were trained, validated, and tested, generating uncertainty estimates. A two-feature Gaussian Naïve Bayes (GNB) model, using the previous five minutes and ten minutes of blood glucose values, showed similar results for predictive accuracy as a threefeature model that included average change over the preceding 30 minutes. The two-feature model was selected because it allowed for a more easily understood visualization of uncertainty. The 2-feature GNB achieved an AUC = .94. The model showed good sensitivity for exceeding the < 180 mg/dl limit, obtaining threshold prediction = 89.8% and normal range prediction = 90.8%. The sensitivity was lower for the < 70 mg/dl limit, attaining a sensitivity = 77.5%. Posterior probabilities showed differing levels of uncertainty in the prediction of high and low out-of-range conditions. The model demonstrated the feasibility of providing robust parameter estimates. Bayesian machine learning approaches to model uncertainty may improve the transparency, explainability, and applicability of AI/ML in medical treatment, realizing the promise to improve patient safety and outcomes.
Texture analysis for tissue characterization is a current area of optical coherence tomography (OCT) research. We discuss some of the differences between OCT systems and the effects those differences have on the resulting images and subsequent image analysis. In addition, as an example, two algorithms for the automatic recognition of bladder cancer are compared: one that was developed on a single system with no consideration for system differences, and one that was developed to address the issues associated with system differences. The first algorithm had a sensitivity of 73% and specificity of 69% when tested using leave-one-out cross-validation on data taken from a single system. When tested on images from another system with a different central wavelength, however, the method classified all images as cancerous regardless of the true pathology. By contrast, with the use of wavelet analysis and the removal of system-dependent features, the second algorithm reported sensitivity and specificity values of 87 and 58%, respectively, when trained on images taken with one imaging system and tested on images taken with another.
The vast majority of bladder cancers originate within 600 µm of the tissue surface, making optical coherence tomography (OCT) a potentially powerful tool for recognizing cancers that are not easily visible with current techniques. OCT is a new technology, however, and surgeons are not familiar with the resulting images. Technology able to analyze and provide diagnoses based on OCT images would improve the clinical utility of OCT systems. We present an automated algorithm that uses texture analysis to detect bladder cancer from OCT images. Our algorithm was applied to 182 OCT images of bladder tissue, taken from 68 distinct areas and 21 patients, to classify the images as noncancerous, dysplasia, carcinoma in situ (CIS), or papillary lesions, and to determine tumor invasion. The results, when compared with the corresponding pathology, indicate that the algorithm is effective at differentiating cancerous from noncancerous tissue with a sensitivity of 92% and a specificity of 62%. With further research to improve discrimination between cancer types and recognition of false positives, it may be possible to use OCT to guide endoscopic biopsies toward tissue likely to contain cancer and to avoid unnecessary biopsies of normal tissue.
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