Increased incidence of interstitial pneumonia detected on [18F]-FDG-PET/CT in asymptomatic cancer patients during COVID-19 pandemic in Lombardy: a casualty or COVID-19 infection?

Abstract

Purpose The study aimed to compare the incidence of interstitial pneumonia on [ 18 F]-FDG PET/CT scans between two 6-month periods: (a) the COVID-19 pandemic peak and (b) control period. Secondly, we compared the incidence of interstitial pneumonia on [ 18 F]-FDG PET/CT and epidemiological data from the regional registry of COVID-19 cases. Additionally, imaging findings and the intensity of [ 18 F]-FDG PET/CT uptake in terms of maximum standardized uptake value (SUVmax) were compared. Methods We retrospectively analyzed [ 18 F]-FDG PET/CT scans performed in cancer patients referred to nuclear medicine of Humanitas Gavazzeni in Bergamo from December 2019 to May 2020 and from December 2018 to May 2019. The per month incidence of interstitial pneumonia at imaging and the epidemiological data were assessed. To evaluate the differences between the two symmetric groups (period of COVID-19 pandemic and control), the stratified Cochran-Mantel-Haenszel test was used. Chi-square test or Fisher's exact test and t test or Wilcoxon test were performed to compare the distributions of categorical and continuous variables, respectively. Results Overall, 1298 patients were included in the study. The two cohorts-COVID-19 pandemic (n = 575) and control (n = 723)-did not statistically differ in terms of age, disease, or scan indication (p > 0.05). Signs of interstitial pneumonia were observed in 24 (4.2%) and 14 patients (1.9%) in the COVID-19 period and the control period, respectively, with a statistically significant difference (p = 0.013). The level of statistical significance improved further when the period from January to May was considered, with a peak in March (7/83 patients, 8.4% vs 3/134 patients, 2.2%, p = 0.001). The curve of interstitial pneumonia diagnosis overlapped with the COVID-19 incidence in the area of Lombardy (Spearman correlation index was equal to 1). Imaging data did not differ among the two cohorts. Conclusions Significant increase of interstitial lung alterations at [ 18 F]-FDG PET/CT has been demonstrated during the COVID-19 pandemic. Additionally, the incidence curve of imaging abnormalities resulted in resembling the epidemiological data of the general population. These data support the rationale to adopt [ 18 F]-FDG PET/CT as sentinel modality to identify suspicious COVID-19 cases to be referred for additional confirmatory testing. Nuclear medicine physicians and staff should continue active surveillance of interstitial pneumonia findings, especially when new infection peak is expected.

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

“…Our results showed a higher rate of interstitial pneumonia during the COVID period compared with the pre-COVID and control periods, in agreement with previous local results [16][17][18][19], but evaluating a larger population and representative of Italy. This national evidence was confirmed also analyzing macro-areas like Northern Italy and Southern Italy-Islands.…”

“…Instead, mediastinal lymph node involvement at PET/CT was discovered in only 37% of all patients studied during the COVID period. These evidences underlined the aggressiveness of interstitial pneumonia which reflect the high metabolic activity at PET and were similar to other studies [16][17][18][19].…”

“…Thus, an accurate analysis of CT images seems to be mandatory also for nuclear medicine physicians with the aim of integrating morphological and metabolic data in the same moment. As reported before [16][17][18][19], we defined viral interstitial pneumonia suspected for COVID-19 infection if pulmonary infiltrates, GGOs, and subpleural pseudo-nodular mixed ground-glass and consolidation areas were present at CT of PET.…”

“…Also fluorine-18-fluorodeoxyglucose positron emission tomography/CT ([ 18 F]FDG PET/CT) is able to reveal lung alterations suspicious for COVID-19 pneumonia despite the sub-optimal diagnostic power of CT (generally low dose) and several cases of incidental interstitial pneumonia COVID-19related detected by [ 18 F]FDG PET/CT in asymptomatic patients are present in literature [10][11][12][13][14][15][16][17][18][19], but these reports are usually case reports or single-center experience.…”

Role of 2-[18F]FDG as a Radiopharmaceutical for PET/CT in Patients with COVID-19: A Systematic Review

“…Conversely, another study did not find a significant difference of 2-[ 18 F]FDG uptake in ground glass pulmonary infiltrates between COVID-19 patients and controls [17]. Some studies reported that the prevalence of incidental pulmonary findings suspicious for interstitial pneumonia by COVID-19 at 2-[ 18 F]FDG PET/CT was higher when compared to 2-[ 18 F]FDG PET/CT scans of the same period one year earlier, without significant differences in 2-[ 18 F]FDG uptake [7,12,13,16].…”