Authors (including presenting author) :
Wong IWC(1), Li CWI(1), Lau JHY (1), Chan TTK(1), Ng KS (1), Ng DKK(1), Chu KS(1), Kung JBT(1), Au Yong TK (1)
Affiliation :
(1) Nuclear Medicine Unit and Clinical PET Centre, Department of Radiology & Imaging, Queen Elizabeth Hospital
Introduction :
In view of emergence of new variants of the coronavirus SARS-CoV-2,the pathogen of Coronavirus Disease 2019 (COVID-19), recommendation of fourth booster shots as well as lowering age limit of vaccination, it is expected that vaccination rate will continue to rise. Vaccine-associated hypermetabolic lymphadenopathy (VAHL) following COVID-19 vaccination is occasionally seen, which may potentially result in misinterpretation of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT).
Objectives :
This study aimed to analyse the incidence, pattern and potential clinical impact of VAHL in oncology patients following COVID-19 vaccination with Sinovac inactivated or BioNTech-Fosun mRNA vaccines.
Methodology :
A total of 165 cancer patients who underwent FDG PET/CT in our institute between 1 May 2021 and 30 September 2021 after first or second COVID-19 vaccination with Sinovac or BioNTech-Fosun were included in this retrospective single-centre study. The occurrence and pattern of FDG uptake at axillary and other regional lymph nodes ipsilateral to vaccine injection site (usually deltoid muscle) was measured.
Result & Outcome :
About one-fourth of the vaccinated oncology patients demonstrated VAHL (26.7%, 44/165), with the greatest percentage seen within first 2 weeks (59.3%). The median maximum standardized uptake value (SUVmax) was 3.2 (range, 1.5-13.8). Even after 6 weeks of COVID-19 vaccination, VAHL was still found in 11.4% (5/44) of the subjects. The occurrence of VAHL was associated with females and mRNA vaccine (p<0.05). In summary, VAHL is common and can persists beyond 6 weeks post-vaccination. Proper documentation of COVID-19 vaccination history has been implemented in our institute, which includes vaccination date(s), type of vaccine, number of dose, and site of vaccine injection, in line with international standards. Reporting physicians can easily access such vaccination history during image report writing. This can facilitate correct image interpretation, avoid unnecessary lymph node biopsy and alteration of treatment.
