title: Breast cancer sentinel node scintigraphy:  differences between imaging results 1 and 2 h after injection.
abstract: BACKGROUND
  Timing of image acquisition in breast cancer sentinel node scintigraphy remains a subject of debate. Therefore, the performance of our protocol in which images are acquired 1 and 2 h after injection was evaluated. The results of sentinel node scintigraphy 1 and 2 h after injection were compared with regard to the sentinel lymph nodes visualized.
  
  
  METHODS
  We studied 132 patients who were consecutively referred for sentinel lymph node biopsy. 99mTc-albumine nanocolloid (120 MBq) was injected peritumourally into patients with palpable tumours and intratumourally into patients with nonpalpable tumours. All scintigraphic images taken for the sentinel node procedure were evaluated. The number of sentinel nodes per anatomic localization and the interpretability of the images were scored.
  
  
  RESULTS
  A total of 132 patients underwent sentinel node scintigraphy 1 h after injection. Of these, 117 patients also underwent sentinel node scintigraphy 2 h after injection. An axillary sentinel node was visualized in 79.5 and 95.7% of patients, respectively, 1 and 2 h after injection. In 20.5% of the patients the images acquired 1 h after injection did not show a sentinel node. Furthermore, in all procedures, the images 1 h after injection were of no added value to those acquired 2 h after injection.
  
  
  CONCLUSIONS
  Scintigraphic imaging 2 h after a single peritumoural or intratumoural administration of about 120 MBq 99mTc-albumine nanocolloid yields an axillary sentinel node in over 95% of cases. Imaging 1 h after injection is of no additional value and can be omitted.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. m.wondergem@umcutrecht.nl
authors.forename: Maurits
authors.initials: M
authors.lastname: Wondergem
authors.forename: Monique G G
authors.initials: MG
authors.lastname: Hobbelink
authors.forename: Arjen J
authors.initials: AJ
authors.lastname: Witkamp
authors.forename: Richard
authors.initials: R
authors.lastname: van Hillegersberg
authors.forename: Bart
authors.initials: B
authors.lastname: de Keizer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D007267:Injections; D008207:Lymphatic Metastasis; D061305:Lymphoscintigraphy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors