Prevalence of interstitial pneumonia suggestive of COVID-19 at 18F-FDG PET/CT in oncological asymptomatic patients in a high prevalence country during pandemic period: a national multi-centric retrospective study
Authors: Albano Domenico , Bertagna Francesco , Alongi Pierpaolo , Baldari Sergio , Baldoncini Alfonso , Bartolomei Mirco , Boccaletto Franco , Boero Michele , Borsatti Eugenio , Bruno Andrea , Burroni Luca , Capoccetti Francesca , Castellani Massimo , Cervino Anna Rita , Chierichetti Franca , Ciarmiello Andrea , Corso Angelo , Cuocolo Alberto , De Rimini Maria Luisa , Deandreis Desiree’ , Dottorini Massimo Eugenio , Esposito Filomena , Farsad Mohsen , Gasparini Massimo , Grana Chiara Maria , Gregianin Michele , Guerra Luca , Loreti Fabio , Lupi Andrea , Martino Gianluigi , Milan Elisa , Modoni Sergio , Morbelli Silvia , Muni Alfredo , Nicolai Emanuele , Palumbo Barbara , Papa Sergio , Papaleo Alberto , Pellerito Riccardo , Poti Carlo , Romano Pasquale , Rossetti Claudio , Rossini Pierluigi , Rubini Giuseppe , Ruffini Livia , Sacchetti Gianmauro , Savelli Giordano , Schiavariello Saverio , Sciagrà Roberto , Sciuto Rosa , Seregni Ettore , Sestini Stelvio , Sicolo Michele , Spanu Angela , Storto Giovanni , Balducci Massimo Tosti , Trifirò Giuseppe , Versari Annibale , Vignati Alberto , Volterrani Duccio , Calcagni Maria Lucia , Marzola Maria Cristina , Garufo Antonio , Evangelista Laura , Maroldi Roberto , Schillaci Orazio , Giubbini Raffaele ,   On the behalf of Italian Association of Nuclear Medicine (AIMN), Bonacina M. , Laudicella R. , Spallino M. , Palucci A. , Cuzzocrea M. , Donner M. , Maurea S. , Ceci F. , Dei Rossi F. , Tranfaglia B. , Sartorello A. , Gandolfo P. , Buschiazzo A. , Scarale A. , Kirienko M. , Merenda N. , Nappi A. G. , Durmo R. , Vellani C. , Ceriani V. 
Published: February 2021

Abstract
Purpose
To assess the presence and pattern of incidental interstitial lung alterations suspicious of COVID-19 on fluorine-18-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) ([18F]FDG PET/CT) in asymptomatic oncological patients during the period of active COVID-19 in a country with high prevalence of the virus.

Methods
This is a multi-center retrospective observational study involving 59 Italian centers. We retrospectively reviewed the prevalence of interstitial pneumonia detected during the COVID period (between March 16 and 27, 2020) and compared to a pre-COVID period (January–February 2020) and a control time (in 2019). The diagnosis of interstitial pneumonia was done considering lung alterations of CT of PET.

Results
Overall, [18F]FDG PET/CT was performed on 4008 patients in the COVID period, 19,267 in the pre-COVID period, and 5513 in the control period. The rate of interstitial pneumonia suspicious for COVID-19 was significantly higher during the COVID period (7.1%) compared with that found in the pre-COVID (5.35%) and control periods (5.15%) (p < 0.001). Instead, no significant difference among pre-COVID and control periods was present. The prevalence of interstitial pneumonia detected at PET/CT was directly associated with geographic virus diffusion, with the higher rate in Northern Italy. Among 284 interstitial pneumonia detected during COVID period, 169 (59%) were FDG-avid (average SUVmax of 4.1).

Conclusions
A significant increase of interstitial pneumonia incidentally detected with [18F]FDG PET/CT has been demonstrated during the COVID-19 pandemic. A majority of interstitial pneumonia were FDG-avid. Our results underlined the importance of paying attention to incidental CT findings of pneumonia detected at PET/CT, and these reports might help to recognize early COVID-19 cases guiding the subsequent management.