Effect of COVID-19 on¹⁸F-FDG PET/CT: Is There a Need to Consider COVID-19 Status Before Planning¹⁸F-FDG PET/CT for Oncologic Evaluation?

Abstract

Incidental detection of coronavirus disease-2019 (COVID-19) related lung changes in 18 F-FDG PET/CT of oncology patients have been increasingly reported. Most of the case reports/series stressed the retrospective diagnosis of COVID-19 with the help of 18 F-FDG PET/CT lung findings.In this case report, we introduce a different aspect of COVID-19 related lung changes in 18 F-FDG PET/CT, interfering with the evaluation of metastatic lung lesions in patients with renal cell carcinoma.

Cannonball appearance, a tricky yet underrated imaging manifestation of COVID-19

“…On the other hand, COVID-19-related pneumonia may obscure both morphological and metabolic features of metastatic cannonball lesions, bringing about diagnostic and monitoring dilemmas. For instance, in patients with metastatic renal cell carcinoma with cannonball appearance, the 18F-fluorodeoxyglucose (FDG) uptake by COVID-19-related lesions in the background may add spill-in counts to the total 18F-FDG uptake in metastatic lesions, resulting in a false high uptake in the metastatic deposits [ 9 , 19 ].…”

“…Additionally, it emphasizing on a diagnostic challenge: In patients with primary malignancy with possibility of cannonball metastases, in this time of COVID-19 pandemic, one should rely on previous imaging and patient’s history before making a misled diagnosis. Moreover, in patients who are known cases of cannonball pulmonary metastases and are being monitored for treatment response, new lesions, or lesions that show no decreased, 18F-FDG uptake in PET scan may not necessarily imply poor treatment response and simultaneous COVID-19 pneumonia is a possibility that needs to be ruled out (especially in suggestive clinical context) [ 19 ].…”

The value of FDG-PET/CT imaging in the assessment, monitoring, and management of COVID-19

“…Although not recommended as a first-line investigative modality, FDG-PET/CT is highly sensitive in the detection of COVID-19-associated pulmonary lesions [ 2 , 3 , 20 , 38 , 44 – 46 ] . Numerous reports dating back to the first months of the pandemic have noted incidental localization of FDG uptake in the lungs of asymptomatic, later COVID-19 positive, patients who had undergone PET imaging for other clinical indications [ 45 , 47 – 53 ] [Fig. 1 —Illustrative figure of classical incidental findings and FDG uptake].…”