Deep Learning Based Automated COVID-19 Classification from Computed Tomography Images

TL;DR

This paper presents a simple yet effective CNN-based method for COVID-19 diagnosis from CT slices, achieving superior accuracy by combining image preprocessing, hyperparameter tuning, and slice voting.

Contribution

It introduces a less complex CNN architecture with enhanced preprocessing and hyperparameter tuning, outperforming state-of-the-art methods on COVID-19 CT classification.

Findings

Achieved higher macro F1 scores than baseline models.

Improved prediction accuracy on unseen test data.

Effective use of slice voting for patient-level diagnosis.

Abstract

A method of a Convolutional Neural Networks (CNN) for image classification with image preprocessing and hyperparameters tuning was proposed. The method aims at increasing the predictive performance for COVID-19 diagnosis while more complex model architecture. Firstly, the CNN model includes four similar convolutional layers followed by a flattening and two dense layers. This work proposes a less complex solution based on simply classifying 2D-slices of Computed Tomography scans. Despite the simplicity in architecture, the proposed CNN model showed improved quantitative results exceeding state-of-the-art when predicting slice cases. The results were achieved on the annotated CT slices of the COV-19-CT-DB dataset. Secondly, the original dataset was processed via anatomy-relevant masking of slice, removing none-representative slices from the CT volume, and hyperparameters tuning. For slice processing, a fixed-sized rectangular area was used for cropping an anatomy-relevant region-of-interest in the images, and a threshold based on the number of white pixels in binarized slices was employed to remove none-representative slices from the 3D-CT scans. The CNN model with a learning rate schedule and an exponential decay and slice flipping techniques was deployed on the processed slices. The proposed method was used to make predictions on the 2D slices and for final diagnosis at patient level, majority voting was applied on the slices of each CT scan to take the diagnosis. The macro F1 score of the proposed method well-exceeded the baseline approach and other alternatives on the validation set as well as on a test partition of previously unseen images from COV-19CT-DB dataset.