Diagnostic and Interventional Radiology
Artificial Intelligence and Informatics - Original Article

Determination of disease severity in COVID-19 patients using deep learning in chest X-ray images


Center for Interventional Oncology, National Institutes of Health Clinical Center and National Cancer Institute, Bethesda, Maryland, USA


Philips Research North America, Cambridge, Massachusetts, USA


NVIDIA Corporation, Bethesda, Maryland, USA


Department of Radiology,Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, University of Milan, Italy


Department of Radiology, University of California Los Angeles, Los Angeles, California, USA


National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA


State University of New York Upstate Medical University, Syracuse, Newyork, USA


Molecular Imaging Program, National Institutes of Health, Bethesda, Maryland, USA


Department of Radiology and Imaging Sciences, National Institutes of Health, Bethesda, Mayland, USA


Clinical Research Directorate, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA


National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland, USA

Diagn Interv Radiol 2021; 27: 20-27
DOI: 10.5152/dir.2020.20205
Read: 983 Downloads: 248 Published: 01 January 2021


Chest X-ray plays a key role in diagnosis and management of COVID-19 patients and imaging features associated with clinical elements may assist with the development or validation of automated image analysis tools. We aimed to identify associations between clinical and radiographic features as well as to assess the feasibility of deep learning applied to chest X-rays in the setting of an acute COVID-19 outbreak.



A retrospective study of X-rays, clinical, and laboratory data was performed from 48 SARS-CoV-2 RT-PCR positive patients (age 60±17 years, 15 women) between February 22 and March 6, 2020 from a tertiary care hospital in Milan, Italy. Sixty-five chest X-rays were reviewed by two radiologists for alveolar and interstitial opacities and classified by severity on a scale from 0 to 3. Clinical factors (age, symptoms, comorbidities) were investigated for association with opacity severity and also with placement of central line or endotracheal tube. Deep learning models were then trained for two tasks: lung segmentation and opacity detection. Imaging characteristics were compared to clinical datapoints using the unpaired student’s t-test or Mann-Whitney U test. Cohen’s kappa analysis was used to evaluate the concordance of deep learning to conventional radiologist interpretation.



Fifty-six percent of patients presented with alveolar opacities, 73% had interstitial opacities, and 23% had normal X-rays. The presence of alveolar or interstitial opacities was statistically correlated with age (P = 0.008) and comorbidities (P = 0.005). The extent of alveolar or interstitial opacities on baseline X-ray was significantly associated with the presence of endotracheal tube (P = 0.0008 and P = 0.049) or central line (P = 0.003 and P = 0.007). In comparison to human interpretation, the deep learning model achieved a kappa concordance of 0.51 for alveolar opacities and 0.71 for interstitial opacities.



Chest X-ray analysis in an acute COVID-19 outbreak showed that the severity of opacities was associated with advanced age, comorbidities, as well as acuity of care. Artificial intelligence tools based upon deep learning of COVID-19 chest X-rays are feasible in the acute outbreak setting.


You may cite this article as: Blain M, Kassin M, Varble N, et al. Determination of disease severity in COVID-19 patients using deep learning in chest X-ray images. Diagn Interv Radiol 2021; 27: 20–27

EISSN 1305-3612