Evolution of ¹⁸F-FDG PET/CT Findings in Patients After COVID-19: An Initial Investigation

Abstract

BackgroundThe aim of this study was to assess the temporal-evolution of pulmonary 18 F-FDG-uptake in patients with Coronavirus Disease (COVID-19) and in Post-COVID-19 Lung-Disease (PCLD). MethodsUsing our hospital's clinical electronic records we retrospectively identified 23 Acute COVID-19, 18 PCLD and 9 completely recovered 18 F-FDG-PET/CT studies during the two peaks of UK pandemic.Pulmonary 18 F-FDG-uptake was measured as a Target-to-Background Ratio (TBRlung=SUVmax/SUVmin) and compared to temporal stage. ResultsIn acute COVID-19, <3 weeks after infection, TBRlung was strongly correlated with time after infection (rs=0.81, p<0.001) and was significantly higher in late-stage than early-stage (p=0.001). In PCLD TBRlung was lower in patients treated with high-dose steroids (p=0.003) and asymptomatic patients (p<0.001). ConclusionPulmonary 18 F-FDG-uptake in COVID-19 increases with time after infection. In PCLD pulmonary 18 F-FDG-uptake rises despite viral clearance suggesting on-going inflammation. There was lower pulmonary 18 F-FDG-uptake in PCLD patients treated with steroids.

[18F]FDG PET signal correlates with markers of neo-angiogenesis in patients with fibrotic interstitial lung disease who underwent lung biopsy: Implication for the use of PET/CT in diffuse lung diseases

“…Previous work has used FDG-PET as a biomarker for personalized guidance of treatment and prognostication in IPF. More recently the use of FDG-PET in other diffuse lung diseases is becoming recognized e.g., in post COVID lung disease [10]. In addition, understanding the basis of the PET signal may offer us mechanistic insights and identify pharmacological targets regarding brosis.…”

The Clinical Utility of Molecular Imaging in COVID-19: An Update

“…Of note, persistantly high FDG uptake has been reported in a subset of COVID-19 patients with delayed recovery. 15 Thornton et al demonstrated persistent increased pulmonary FDG uptake in patients with post-COVID-19 lung disease (PCLD), and higher in untreated patients compared to those who received high-dose steroids and those who were asymptomatic. The authors concluded that FDG PET/CT may play a role in understanding COVID-19 disease trajectory and guide management for those patients with persistent respiratory symptoms.…”

“…The authors concluded that FDG PET/CT may play a role in understanding COVID-19 disease trajectory and guide management for those patients with persistent respiratory symptoms. 15 …”

Oncology and cardiology positron emission tomography/computed tomography faced with COVID-19: A review of available literature data

“…However, an FDG PET/CT study revealed that significant inflammation remained in the lungs, mediastinal LNs, spleen, and liver after two consecutive negative RT-PCR tests in patients recovering from severe COVID-19 infection (47,48). The dissociation between recovery according to CT and delayed recovery of FDG uptake in COVID-19 lesions indicated that a high level of inflammatory change persisted even in the recovery stage with an activated host immune response and/or angiovascular damage (46,(48)(49)(50). 18 F-fluorodeoxyglucose uptake in lymph nodes of patients with COVID-19 18 F-fluorodeoxyglucose uptake in normal-sized LNs is a common observation in patients with COVID-19 and is thought to indicate immunoreactions activated by inflammatory cells such as neutrophils, monocytes, and effector T cells by the release of local chemokines.…”