Coordination and optimization of FDG PET/CT and COVID-19 vaccination; Lessons learned in the early stages of mass vaccination

Abstract

As the world embarks on mass vaccination for COVID-19, we are beginning to encounter unintended dilemmas in imaging oncology patients; particularly with regards to FDG PET/CT. In some cases, vaccine-related lymphadenopathy and FDG uptake on PET/CT can mimic cancer and lead to confounding imaging results. These cases with findings overlapping with cancer pose a significant dilemma for diagnostic purposes, follow-up, and management leading to possible treatment delays, unnecessary repeat imaging and sampling, and patient anxiety. These cases can largely be avoided by optimal coordination between vaccination and planned imaging as well as preemptive selection of vaccine administration site. This coordination hinges on patient, oncologist, and radiologists’ awareness of this issue and collaboration. Through close communication and patient education, we believe this will eliminate significant challenges for our oncology patients as we strive to end this pandemic.

Prevalence and Significance of Hypermetabolic Lymph Nodes Detected by 2-[18F]FDG PET/CT after COVID-19 Vaccination: A Systematic Review and a Meta-Analysis

“…During the SARS-CoV-2 pandemic several 2-[ 18 F]FDG PET/CT imaging findings associated with COVID-19 were described [ 19 , 20 , 21 ]. Further 2-[ 18 F]FDG PET/CT findings were described after the introduction of COVID-19 vaccines [ 5 , 6 , 9 ], in particular HALNs ipsilateral to the vaccine injection site. Our systematic review and meta-analysis clearly demonstrates that this 2-[ 18 F]FDG PET/CT finding is frequent after recent COVID-19 vaccination and it is due to immune response to the vaccine in most of the cases [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”

“…This is not surprising as functional/metabolic abnormalities detected by 2-[ 18 F]FDG PET usually precede morphological abnormalities detected by CT scan and other conventional imaging methods [ 7 ]. Furthermore, the pooled prevalence of HALNs detected by 2-[ 18 F]FDG PET/CT was higher than the prevalence of axillary lymphadenopathies (short axis >10 mm) detected by conventional imaging techniques after COVID-19 vaccinations [ 5 , 6 , 9 ].…”

“…Due to their immunological effects, vaccinations including those related to COVID-19 may cause various confusing imaging patterns that pose diagnostic challenges for clinicians and pitfalls for reading radiologists and nuclear medicine physicians [ 3 , 4 , 5 , 6 ]. On the other hand, some imaging methods could be of potential value to assess the immune response after vaccination, including those related to COVID-19 [ 3 , 4 ].…”

“…Incidental lesions detected by whole-body 2-[ 18 F]FDG PET/CT performed for several indications are widely described in the literature [ 8 ]. Since the COVID-19 vaccination programs began worldwide, several articles (mainly case reports) reported incidental findings at 2-[ 18 F]FDG PET/CT in patients who have received recent COVID-19 vaccinations [ 5 , 6 , 9 ]. These findings due to vaccine-related immune response are mainly represented by hypermetabolic axillary lymph nodes (HALNs) ipsilateral to the COVID-19 vaccine injection site (a case example is reported in Figure 1 ) and 2-[ 18 F]FDG uptake in the vaccine injection site [ 5 , 6 , 9 ].…”

Metabolic Activity Assessment by 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients after COVID-19 Vaccination

“…Moreover, during periods of infection, active fibrosis, and active granulomatous processes such as sarcoidosis, there is hypermetabolic uptake of FDG that often results in false-positive PET-CT scans for malignancy [ 16 ]. Since the initiation of the global COVID-19 vaccination programs, multiple studies have cited the occurrence of hypermetabolic axillary lymph nodes in patients after receiving the COVID-19 vaccine, which has complicated accurate diagnosis [ 11 , 17 , 18 ]. A meta-analysis including over 2000 patients undergoing 2-[18F]-FDG PET/CT revealed hyper-metabolic axillary lymph nodes with a prevalence of 37% after COVID-19 vaccination [ 19 ].…”