Incidence of [18F]FDG PET/CT lung findings suspected for COVID-19 in asymptomatic oncological patients after the first pandemic peak in Italy

ABSTRACT

Background-Aim: The SARS-CoV-2 infection was declared a global pandemic in March 2020 and initially had a wide diffusion in Northern Italy, especially in area of Bergamo. From December 2019 to May 2020 (peak of pandemic period), an increase of interstitial pneumonia cases was observed at [18F]FDG PET/CT in oncological patients in Bergamo area. Further, a significant increase of PETpositive interstitial lung alterations was found with higher incidence compared to the pre-pandemic period. These observations suggested the use of [18F]FDG PET/CT as a sentinel method to identify suspected cases of COVID-19 in asymptomatic oncological patients. This observational prospective multicentric study aimed at confirming the usefulness of [18F]FDG PET/CT in the occasional diagnosis of COVID-19. Methods: [18F]FDG PET/CT performed in oncological patients from May 2020 to January 2021 (post pandemic peak period) in 8 Nuclear Medicine Departments in Lombardy (Humanitas Gavazzeni Bergamo, IRCCS Humanitas Rozzano, IRCCS San Raffaele Milano, Ospedale San Gerardo Monza, IRCCS Ca'Granda Ospedale Maggiore Milano, IRCCS Istituto Nazionale Tumori, Milano) and Tuscany (Azienda USL Nord Ovest Livorno, Azienda Ospedaliera Universitaria Pisana, Pisa) were assessed. The PCR test was proposed to all patients with lung alterations suspected for COVID-19 to confirm the diagnosis of SARS-CoV-2 infection. Results: Overall 19814 patients were studied with [18F]FDG PET/CT for various oncological diseases in the Nuclear Medicine Departments of the Centers involved in the study. We identified 54 out of 19,814 (0.27%) [18F]FDG PET/CT with lung alterations suspected for COVID-19 interstitial pneumonia. 45/54 suspected patients underwent rhinopharyngeal swab for confirmation. 9 patients with lung imaging alterations did not undergo PCR confirmation. PCR test detected 11 positive cases (24% of patients who underwent PCR test). The incidence of PCR confirmed COVID-19 was 11 out of 19,814 (0.06%). Conclusions: Among oncological asymptomatic patients who underwent PET/CT, we identified by PCR test very few cases of COVID-19 pneumonia. This could result from two main reasons firstly, the low incidence of COVID-19 in the examined period, as confirmed by the epidemiological curve, and, secondly, the effectiveness of environmental and personal hygiene, social distancing, the use of personal protective equipment. However, although PET/CT imaging is not a reference test for the diagnosis of COVID-19 pneumonia, this study demonstrated that [18F]FDG PET/CT can identify lung manifestations of COVID-19.