Can I have a COVID-19 vaccination before a CT scan?
It is important to advise your oncologist or radiographer if you have received the COVID-19 vaccine recently. This is because the vaccine can cause the lymph nodes in your armpit and neck to swell which can be detected by CT scans used to diagnose and monitor cancers.
This is particularly detected by FDG PET/CT scans, in which you are given a contrast medium containing a type of radioactive sugar that is taken up by active cells. When an immune response to a vaccine takes place, the cells in the lymph nodes near the injection site become very active and take up a lot of this sugar. Depending on the type of cancer, you may be able to request the injection on the opposite side to your tumour. If possible, have the vaccination at least 2 weeks before a scheduled scan or as soon as you can afterwards. Do not delay any treatment.
McIntosh LJ, Bankier AA, Vijayaraghavan GR, et al. COVID-19 Vaccination-Related Uptake on FDG PET/CT: An Emerging Dilemma and Suggestions for Management. American Journal of Roentgenology. 2021. doi: 10.2214/AJR.21.25728