CT Image Analysis Using Grayscale Statistics to Categorise Severity of Lung Abnormalities of COVID-19 Patients
Abstract Grayscale image attributes from 456 images extracted from CT scan slices of 53 patients (49 with COVID-19 and 4 without) are used to establish a visual scale of severity of lung abnormalities (five classes: 0 to 4). The complex trends of these easy-to-derive image attributes can be used graphically to discern the visual scale of lung abnormalities in broad terms. With the aid of machine learning algorithms, the visual classes can be distinguished with close to 95% accuracy using combinations of selected grayscale attributes. Confusion matrices reveal that the best-performing machine learning models are able to distinguish more accurately between certain classes than visual inspection of CT images by experts. The adaboost, decision tree and random forest models confused on average less than 25 of the 456 CT-scan image extracts evaluated between the visual classes of lung abnormalities.