ARRS 2022 Abstracts

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E1378. Features of COVID-19 Infection and Vaccination on PET Imaging: An Educational Exhibit
Authors
  1. Katherine Smith; Mayo Clinic
  2. Hiroaki Takahashi; Mayo Clinic
  3. Geoffrey Johnson; Mayo Clinic
Background
The imaging findings related to COVID-19 can be quite variable. The imaging presentation of COVID-19 on chest CT and radiographs has been extensively described, but the presentation of COVID-19 on other imaging modalities is less well known. Furthermore, we are finding that the imaging findings related to COVID-19 vaccination present a unique challenge across multiple divisions of radiology, including breast, thoracic, and abdominal imaging. PET-CT presents similar challenges, and the findings of resolving COVID-19 infection or recent vaccination can complicate the accurate interpretation of these exams for patients with cancer. Herein we describe our experience with PET-CT imaging in patients with diagnosis of COVID-19 infection and prior COVID-19 vaccination.

Educational Goals / Teaching Points
Describe the typical PET-CT findings of patients with COVID-19 infection using several radiotracers, including 18F-FDG, carbon-11 choline (C-11 choline), gallium-68 DOTATATE (Ga-68 DOTATATE), and gallium-68 prostate-specific membrane antigen-11 (Ga-68 PSMA-11). Highlight pitfalls in the evaluation of previously infected patients. Illustrate with examples how to approach challenging scenarios in patients with infection and concomitant malignancy. Describe typical PET-CT findings in patients who received COVID-19 vaccination and highlight pitfalls.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
In this educational review, we will present multiple cases to review the imaging findings of active COVID-19 infection and recent COVID-19 vaccination on PET-CT. The typical imaging findings will be discussed for 18F-FDG, C-11 choline, Ga-68 DOTATATE, and Ga-68 PSMA-11. Patients with active COVID-19 infection or recent COVID-19 vaccination can demonstrate increased radiotracer uptake in both the lungs and lymph nodes on PET-CT. Often, the metabolically active lymph nodes in patients with active COVID-19 infection are not enlarged, unlike what we would typically see with other infectious lung pathologies. We have observed multiple cases clinically in which the PET-CT findings associated with resolving COVID-19 infections and recent COVID-19 vaccinations have demonstrated findings that overlap with the expected PET-CT findings in cancer. In particular, the COVID-19 vaccination can produce an unexpectedly robust lymph node response that we do not typically see with other vaccinations. We hope to describe the PET-CT imaging findings in these patients to better describe this entity on PET-CT and identify possible pitfalls in interpretation of these exams in patients with cancer.

Conclusion
Patients with active COVID-19 infection or recent COVID-19 vaccination can present imaging pitfalls to differentiate between COVID-related findings and malignancy. The radiologist should be aware of this possibility when interpreting PET-CT to provide a more informed interpretation.