Detection of COVID-19 pulmonary manifestations with radiotherapy simulation CT imaging

COVID-19 is associated with characteristic lung CT findings. Radiotherapy simulation CT scans may reveal characteristic COVID-19 findings and identify patients with active or prior infection. We reviewed patients undergoing CT simulation at a major cancer center in an early epicenter of the COVID-19 pandemic in the United States. Scans were reviewed by radiation oncologists using established radiographic criteria for COVID-19 pneumonia. Radiographic classifications were compared with available COVID-19 PCR test results. A one-tailed t-test was used to compare the rate of positive COVID-19 tests in radiographically suspicious vs. non-suspicious groups. Scans deemed suspicious were re-reviewed by expert diagnostic radiologists. 414 CT simulation scans were performed on 400 patients. 119 patients had COVID-19 PCR test results available. Radiation oncologists considered 71 scans (17.1%) suspicious for COVID-19. Of these, 23 had corresponding COVID-19 PCR tests, and 3/23 (15.7%) were positive for COVID. 107 non-suspicious scans had corresponding COVID-19 test results, and 9 were positive (8.4%). The difference in positive test results between suspicious and non-suspicious groups was not significant (p = 0.23). Upon re-review by a diagnostic radiologist, 25 (35%) scans deemed suspicious by radiation oncologists were confirmed to meet criteria, while the rest were re-classified as "atypical" for COVID-19. We conclude that radiotherapy simulation CT scans can be reviewed for signs of COVID-19 pneumonia by radiation oncologists. However, suspicious CT simulation was not associated with a higher incidence of COVID infection compared with non-suspicious CT simulation, and there was low concordance between radiation oncologist and diagnostic radiologist classification of scans.