title: Duration of 18F-FDG avidity in lymph nodes after pandemic H1N1v and seasonal influenza vaccination.
abstract: OBJECTIVE
  The aim of our study was to investigate the occurrence of fluorodeoxyglucose (FDG) avidity in draining axillary lymph nodes after vaccination against influenza (H1N1v pandemic and seasonal) and to determine the period of increased FDG uptake.
  
  
  METHODS
  During December 2009, patients referred for (18)F-FDG positron emission tomography (PET)/CT scans (n = 293) filled in a questionnaire concerning vaccination type (seasonal and/or H1N1v), time and anatomical localization of vaccination. Only injections in deltoid regions were evaluated, thus ensuring that draining lymph nodes were axillary. If more vaccinations had been given, only the latest vaccination was evaluated in each deltoid region.
  
  
  RESULTS
  Of all patients who underwent PET/CT scans during December 2009, 26% had been vaccinated with at least one influenza vaccination in the deltoid region. A total of 92 'draining' and 60 'reference' (i.e. contralateral, non-vaccinated) axillary lymph nodes were evaluated in 61 patients (19 of 61 patients were scanned twice). The maximal intensity in FDG uptake (SUV(max)) in draining lymph nodes was 5 g/ml body weight (BW), whereas the maximal intensity in reference lymph nodes was 1.9 g/ml BW. The SUV(max) was normalized approximately 40 days after vaccination. No significant enlargement of metabolically active draining lymph nodes could be demonstrated on CT scan. Chemotherapy or immunosuppressive drugs given within 2 weeks from vaccination did not affect SUV(max) in the axillary lymph nodes.
  
  
  CONCLUSIONS
  Influenza vaccination may lead to FDG-avid draining lymph nodes beyond 1 month.
authors.affiliation: Department of Nuclear Medicine, OUH, Odense University Hospital, 5000 Odense C, Denmark. anders.thomassen@ouh.regionsyddanmark.dk
authors.forename: Anders
authors.initials: A
authors.lastname: Thomassen
authors.forename: Anne
authors.initials: A
authors.lastname: Lerberg Nielsen
authors.forename: Oke
authors.initials: O
authors.lastname: Gerke
authors.forename: Allan
authors.initials: A
authors.lastname: Johansen
authors.forename: Henrik
authors.initials: H
authors.lastname: Petersen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D002648:Child; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000502:physiology*; D007251:Influenza, Human / Q000000981:diagnostic imaging / Q000378:metabolism / Q000517:prevention & control*; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000517:prevention & control*; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012621:Seasons; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014611:Vaccination; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18