title: The hidden sentinel node in breast cancer: Reevaluating the role of SPECT/CT and tracer reinjection.
abstract: BACKGROUND
  Lymphoscintigraphy with planar imaging is considered a helpful tool to depict lymph node drainage in patients with invasive breast cancer. Single Photon Emission Computed Tomography with integrated CT (SPECT/CT) is usually performed to detect sentinel nodes (SN)s in breast cancer patients showing non-visualisation on lymphoscintigraphy. Incorporation of new SN indications (recurrent surgery, previous radiotherapy, or neo-adjuvant chemotherapy) has led to an increase of non-visualisation rates. The present study evaluates the contribution of SPECT/CT and tracer reinjection for SN-visualisation in breast cancer patients without drainage on lymphoscintigraphy.
  
  
  METHODS
  Between 1st of July 2008 and 6th of November 2014 in total 1968 patients underwent a SN breast procedure, using intra-tumoural tracer administration. SPECT/CT was performed in 284 breast cancer patients with non-visualisation of SNs on lymphoscintigraphy. If SN non-visualisation persisted, a second radiotracer injection with repeated imaging was performed when logistics allowed this. Univariate analysis was applied to evaluate SPECT/CT visualisation rates in specific subgroups.
  
  
  RESULTS
  The SPECT/CT visualisation rate was 23.2% (66/284). Univariate analysis revealed no significant subgroups influencing SPECT/CT visualisation. In patients receiving reinjection after persistent SPECT/CT non-visualisation the SN-visualisation rate reached 62.1% (36/58). Intraoperatively, the SN-identification rate using a gamma probe and blue dye was 87.9% (175/199) and 32.9% (28/85) for, respectively, primary and recurrent surgery after non-visualisation on lymphoscintigraphy.
  
  
  CONCLUSIONS
  In this evaluation including new breast cancer SN indications, SPECT/CT scored lower than reinjection to visualise SNs in patients with non-visualisation on lymphoscintigraphy. Consequently, our institutional protocol has been readjusted.
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: bas.pouw@gmail.com.
authors: B
authors: B
authors: Pouw
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: daanhellingman@gmail.com.
authors: D
authors: D
authors: Hellingman
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: m.kieft@nki.nl.
authors: M
authors: M
authors: Kieft
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: w.vogel@nki.nl.
authors: W V
authors: WV
authors: Vogel
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: k.v.os@nki.nl.
authors: K J
authors: KJ
authors: van Os
authors: Department of Surgical Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: e.rutgers@nki.nl.
authors: E J T
authors: EJ
authors: Rutgers
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: r.valdes@nki.nl.
authors: R A
authors: RA
authors: Valdés Olmos
authors: Department of Nuclear Medicine, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. Electronic address: m.stokkel@nki.nl.
authors: M P M
authors: MP
authors: Stokkel
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000556:secondary; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015552:Injections, Intralesional; D008207:Lymphatic Metastasis; D008875:Middle Aged; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Breast cancer; Non-visualisation; SLNB; SPECT/CT; Sentinel node