  COVID-19 infection caused by SARS-CoV-2 pathogen is a catastrophic pandemic
outbreak all over the world with exponential increasing of confirmed cases and,
unfortunately, deaths. In this work we propose an AI-powered pipeline, based on
the deep-learning paradigm, for automated COVID-19 detection and lesion
categorization from CT scans. We first propose a new segmentation module aimed
at identifying automatically lung parenchyma and lobes. Next, we combined such
segmentation network with classification networks for COVID-19 identification
and lesion categorization. We compare the obtained classification results with
those obtained by three expert radiologists on a dataset consisting of 162 CT
scans. Results showed a sensitivity of 90\% and a specificity of 93.5% for
COVID-19 detection, outperforming those yielded by the expert radiologists, and
an average lesion categorization accuracy of over 84%. Results also show that a
significant role is played by prior lung and lobe segmentation that allowed us
to enhance performance by over 20 percent points. The interpretation of the
trained AI models, moreover, reveals that the most significant areas for
supporting the decision on COVID-19 identification are consistent with the
lesions clinically associated to the virus, i.e., crazy paving, consolidation
and ground glass. This means that the artificial models are able to
discriminate a positive patient from a negative one (both controls and patients
with interstitial pneumonia tested negative to COVID) by evaluating the
presence of those lesions into CT scans. Finally, the AI models are integrated
into a user-friendly GUI to support AI explainability for radiologists, which
is publicly available at http://perceivelab.com/covid-ai.
