Detection of COVID-19 with CT Images using Hybrid Complex Shearlet Scattering Networks.

With the ongoing worldwide coronavirus disease 2019 (COVID-19) pandemic, it is desirable to develop effective algorithms for the automatic detection of COVID-19 with chest computed tomography (CT) images. As deep learning has achieved breakthrough results in numerous computer vision and image understanding tasks, a good choice is to consider diagnosis models based on deep learning. Recently, a considerable number of methods have indeed been proposed. However, training an accurate deep learning model requires a large-scale chest CT dataset, which is hard to collect due to the high contagiousness of COVID-19. To achieve improved COVID-19 detection performance, this paper proposes a hybrid framework that fuses the complex shearlet scattering transform (CSST) and a suitable convolutional neural network into a single model. The introduced CSST cascades complex shearlet transforms with modulus nonlinearities and low-pass filter convolutions to compute a sparse and locally invariant image representation. The features computed from the input chest CT images are discriminative for the detection of COVID-19. Furthermore, a wide residual network with a redesigned residual block (WR2N) is developed to learn more granular multiscale representations by applying it to scattering features. The combination of the model-based CSST and data-driven WR2N leads to a more convenient neural network for image representation, where the idea is to learn only the image parts that the CSST cannot handle instead of all parts. The experimental results obtained on two public chest CT datasets for COVID-19 detection demonstrate the superiority of the proposed method. We can obtain more accurate results than several state-of-the-art COVID-19 classification methods in terms of measures such as accuracy, the F1-score, and the area under the receiver operating characteristic curve.