title: Intraoperative 3D Navigation for Single or Multiple 125I-Seed Localization in Breast-Preserving Cancer Surgery.
abstract: BACKGROUND
  Mammographic screening has led to the identification of more women with nonpalpable breast cancer, many of them to be treated with breast-preserving surgery. To accomplish radical tumor excision, adequate localization techniques such as radioactive seed localization (RSL) are required. For RSL, a radioactive I-seed is implanted central in the tumor to enable intraoperative localization using a γ-probe. In case of extensive tumor or multifocal carcinoma, multiple I-seeds can be used to delineate the involved area. Preoperative imaging is performed different from surgical positioning; therefore, exact I-seed depth remains unknown during surgery.
  
  
  METHODS
  Twenty patients (mean age, 56.8 years) with 25 implanted I-seeds scheduled for RSL were included. Sixteen patients had 1 I-seed implanted in the primary lesion, 3 patients had 2 I-seeds, and 1 patient had 3 I-seeds. Freehand SPECT localized I-seeds by measuring γ-counts from different directions, all registered by an optical tracking system. A reconstruction and visualization algorithm enabled 3-dimensional (3D) navigation toward the I-seeds.
  
  
  RESULTS
  Freehand SPECT visualized all I-seeds in primary tumors and provided preincision depth information. The deviation, mean (SD), between the freehand SPECT depth and the surgical depth estimation was 1.9 (2.1) mm (range, 0-7 mm). Three-dimensional freehand SPECT was especially useful identifying multiple implanted I-seeds because the conventional γ-probe has more difficulty discriminating I-seeds transcutaneous.
  
  
  CONCLUSIONS
  Freehand SPECT with 3D navigation is a valuable tool in RSL for both single and multiple implanted I-seeds in breast-preserving cancer surgery. Freehand SPECT provides continuous updating 3D imaging with information about depth and location of the I-seeds contributing to adequate excision of nonpalpable breast cancer.
authors.affiliation: From the Departments of *Nuclear Medicine, and †Surgical Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Pouw
authors.forename: Linda J
authors.initials: LJ
authors.lastname: de Wit-van der Veen
authors.forename: Frederieke
authors.initials: F
authors.lastname: van Duijnhoven
authors.forename: Emiel J Th
authors.initials: EJ
authors.lastname: Rutgers
authors.forename: Marcel P M
authors.initials: MP
authors.lastname: Stokkel
authors.forename: Renato A
authors.initials: RA
authors.lastname: Valdés Olmos
authors.forename: Marie-Jeanne T F D
authors.initials: MJ
authors.lastname: Vrancken Peeters
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008875:Middle Aged; D019275:Radiopharmaceuticals; D025321:Surgery, Computer-Assisted / Q000379:methods; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals