ARRS 2022 Abstracts

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E1825. Recognition of Locoregional and Systemic Reactive Changes to mRNA-Based COVID-19 Vaccination on Oncological PET/CT
Authors
  1. Ming Yang; Mayo Clinic Arizona
  2. Mathew Smith; Mayo Clinic Arizona
  3. Aaron Yang; Mayo Clinic Arizona
Background
Locoregional reactive lymphadenopathy to mRNA-based COVID-19 vaccination is frequently encountered in clinical practice with PETimaging. In this exhibit, we illustrate tracer-avid axillary and supraclavicular lymph nodes and systemic changes in various malignancies on PET/CT and PET/MR. We also seek to elucidate the vaccination-induced immune response via metabolic pathways of different clinical PET tracers.

Educational Goals / Teaching Points
After viewing the exhibit, the audience should 1) be familiar with mechanism of the immunity establishment following mRNA-based COVID-19 vaccination; 2) recognize the common location and imaging features of reactive lymph nodes at axilla, supraclavicular, and cervical regions and be aware of suspicious uncommon systemic changes on PET/CT and PET/MR; 3) distinguish reactive lymph nodes from malignancies using different clinical PET tracers; and 4) understand the metabolic pathways of different clinical PET tracers, including F18-FDG, Ga68-DOTATATE, and C11-Choline.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
This exhibit will review locoregional and systemic reactive changes to vaccination on F18-FDG PET/CT and PET/MR, including breast cancer, lymphoma, sarcoma, head/neck cancer, neurofibromatosis type 1, and renal cell carcinoma. We also review reactive lymph nodes in a neuroendocrine tumor and biochemically recurrent prostate cancer on Ga68-DOTATATE and C11-Choline PET/CTs. Lastly, we compare metabolic pathways among F18-FDG (up-regulation of glucose transporter), Ga68-DOTATATE (expression of somatostatin receptor), and C11-Choline (hyperfunctioning of choline kinase in cell membrane synthesis).

Conclusion
Ipsilateral axially and supraclavicular reactive lymph nodes are common findings on oncological PET scans following mRNA-based COVID-19 vaccination. Nuclear radiologists should be cautious of common and uncommon reactive changes. In addition, familiarity with the metabolism of different clinical PET tracers is useful in understanding the establishment of immunity.