title: Axillary lymph node accumulation on FDG-PET/CT after influenza vaccination.
abstract: OBJECTIVE
  2-[(18)F]fluoro-2-deoxy-D: -glucose (FDG) is known to accumulate in benign conditions such as infection and inflammation as well as in malignancy. Vaccination may cause transient inflammation of lymph nodes, which may induce false-positive findings on FDG-positron emission tomography (PET) imaging. This study investigated the influence of influenza vaccination on FDG-PET/CT imaging in normal subjects.
  
  
  METHODS
  Between November 2008 and March 2009, a total of 172 examinees underwent FDG-PET/CT during an annual cancer-screening program at our hospital, 83 of whom had a history of recent non-adjuvanted seasonal influenza vaccination. They were asked the date and injection site of the vaccination. Examinees were divided into 2 groups based on the interval after vaccination using a cutoff value of 7 days (1 week). Two double board-certified nuclear medicine physicians and radiologists visually interpreted the FDG-PET/CT images with reference to PET/CT fusion and CT images and checked the location and the number of abnormal accumulations by consensus reading.
  
  
  RESULTS
  Intervals between vaccination and FDG-PET were less than 7 days in 5 examinees, and 7 days or more in 78 examinees. Unexpected accumulations were visualized in 4 examinees in the axilla and medial upper arm, and all of them belonged to the group who underwent vaccination less than 7 days previously. In the second group there was no abnormal FDG accumulation.
  
  
  CONCLUSIONS
  Recent influenza vaccination before FDG-PET/CT examination may cause ipsilateral axillary lymph node accumulations, especially within several days after vaccination. Questionnaires about vaccination can help to avoid false interpretation of FDG avid axillary lymph nodes.
authors.affiliation: Department of Radiology, Takai Hospital, Tenri, Nara, Japan. shirone@takai-hp.com
authors.forename: Norihisa
authors.initials: N
authors.lastname: Shirone
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shinkai
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Yamane
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Uto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yoshimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tamai
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Imai
authors.forename: Makoto
authors.initials: M
authors.lastname: Inoue
authors.forename: Satoru
authors.initials: S
authors.lastname: Kitano
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hasegawa
mesh_terms: D000328:Adult; D016477:Artifacts; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D007251:Influenza, Human / Q000517:prevention & control*; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012621:Seasons; D014057:Tomography, X-Ray Computed; D014611:Vaccination / Q000009:adverse effects*
chemical_list: D019788:Fluorodeoxyglucose F18