Computer-aided diagnosis for characterisation of colorectal lesions: a comprehensive software including serrated lesions

Abstract Background and Aims Endoscopy guidelines recommend adhering to policies such as resect-and-discard only if optical biopsy is accurate. However, accuracy in predicting histology can vary greatly. Computer-aided diagnosis (CAD) for characterization of colorectal lesions may help with this issue. In this study, a CAD software developed at the University of Adelaide (Australia) including serrated polyp differentiation was validated with Japanese images on narrow-band imaging (NBI) and blue-laser imaging (BLI). Methods A CAD software developed using machine learning, densely connected convolutional neural networks was modeled with NBI colorectal lesion images (Olympus 190 series - Australia) and validated for NBI (Olympus 290 series) and BLI (Fujifilm 700 series) with Japanese datasets. All images were correlated with histology according to the modified Sano's classification. The CAD was trained with Australian NBI images and tested with separate sets of images from Australia (NBI) and Japan (NBI and BLI). Results An Australian dataset of 1,235 polyp images was used as training, testing, and internal validation sets. A Japanese dataset of 20 polyp images on NBI and 49 polyp images on BLI was used as external validation sets. The CAD software had a mean area under the curve (AUC) of 94.3% for the internal set and 84.5% and 90.3% for the external sets (NBI and BLI, respectively). Conclusions The CAD achieved AUC comparable with experts and similar results with NBI and BLI. Accurate CAD prediction was achievable even when the predicted endoscopy imaging technology was not part of the training set.