An ensemble deep learning for automatic prediction of papillary thyroid carcinoma using fine needle aspiration cytology.

• Deep learning for identifying papillary thyroid carcinomas and computing certainty. • Ensemble technique combines multiple deep CNNs to significantly increase accuracies. • GRAD-CAM method highlights dominant tissues for the discriminative decision-making. • Effectiveness of stain normalization methods on predictive performances is evaluated. • Proposed ensemble learning is superior to current models for automatic diagnosis. Accurately cytopathological diagnosis of Papillary Thyroid Carcinoma (PTC) is of importance for reducing costs and increasing efficiency of treatments. In this paper, we pursue that goal by introducing artificial intelligence (AI) for automatic classification of malignant PTC cell clusters from Fine Needle Aspiration Cytology (FNAC) processed by ThinPrep. High-resolution cytological images obtained with a 40 × objective lens digital camera attached to an Olympus microscope were segmented into fragments and then divided into training, validation, and testing subsets. Fragments are non-overlapped patches containing only regions-of-interest that cover informative tissue structures for making proper diagnoses. Deep learning CNN models were pre-trained and fine-tuned on large-scale ImageNet domain before they were re-trained on cytology fragments. Moreover, we proposed a method to compute certainty of the patient-level prediction that undoubtedly provides additional evidence for reliability and confidence of the prediction. Results showed that the best classification performance on digital FNAC images achieved using DenseNet161, obtaining a mean accuracy of 0.9556 (p < 0.01), a mean sensitivity of 0.9734, and a mean specificity of 0.9405 on yet-to-be-seen test-set. Ensemble learning findings suggested combinations of AdaBoost classifier with multiple CNN models boosted predictive performances, up to 0.9971 accuracy. Moreover, stain normalization introduced by Reinhard increased the predictive ability, outperforming histogram specification, and Macenko methods. Presented findings demonstrate deep learning can integrate into computer-aided diagnosis systems to support cytopathologists in accurate diagnosis of PTC. [ABSTRACT FROM AUTHOR]