title: Optimising magnetic sentinel lymph node biopsy in an in vivo porcine model.
abstract: The magnetic technique for sentinel lymph node biopsy (SLNB) has been evaluated in several clinical trials. An in vivo porcine model was developed to optimise the magnetic technique by evaluating the effect of differing volume, concentration and time of injection of magnetic tracer. A total of 60 sentinel node procedures were undertaken. There was a significant correlation between magnetometer counts and iron content of excised sentinel lymph nodes (SLNs) (r=0.82; P<0.001). Total number of SLNs increased with increasing volumes of magnetic tracer (P<0.001). Transcutaneous magnetometer counts increased with increasing time from injection of magnetic tracer (P<0.0001), plateauing within 60min. Increasing concentration resulted in higher iron content of SLNs (P=0.006). Increasing magnetic tracer volume and injecting prior to surgery improve transcutaneous 'hotspot' identification but very high volumes, increase the number of nodes excised.
  
  
  BACKGROUND
  Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging of breast cancer patients. Although the current gold standard technique is the combined injection of technetium-labelled nanocolloid and blue dye into the breast, the magnetic technique, using superparamagnetic carboxydextran-coated iron oxide (SPIO), has also been demonstrated as a feasible alternative. In this article, the authors set up to study factors in order to optimize the magnetic tracers.
authors: Research Oncology, Division of Cancer Studies, King's College London, Guy's Hospital, London, UK.
authors: Muneer
authors: M
authors: Ahmed
authors: Research Oncology, Division of Cancer Studies, King's College London, Guy's Hospital, London, UK.
authors: Bauke
authors: B
authors: Anninga
authors: Institute for Biomedical Technology and Technical Medicine, Universiteit Twente, Enschede, The Netherlands.
authors: Joost J
authors: JJ
authors: Pouw
authors: Institute for Biomedical Technology and Technical Medicine, Universiteit Twente, Enschede, The Netherlands.
authors: Suzan
authors: S
authors: Vreemann
authors: Research Oncology, Division of Cancer Studies, King's College London, Guy's Hospital, London, UK; Institute for Biomedical Technology and Technical Medicine, Universiteit Twente, Enschede, The Netherlands.
authors: Mirjam
authors: M
authors: Peek
authors: King's College London, School of Medicine, Cancer Epidemiology Group, Guy's Hospital, London, UK.
authors: Mieke
authors: M
authors: Van Hemelrijck
authors: Research Oncology, Division of Cancer Studies, King's College London, Guy's Hospital, London, UK.
authors: Sarah
authors: S
authors: Pinder
authors: Institute for Biomedical Technology and Technical Medicine, Universiteit Twente, Enschede, The Netherlands.
authors: Bennie
authors: B
authors: Ten Haken
authors: Institute of Biomedical Engineering, University College London, London, UK.
authors: Quentin
authors: Q
authors: Pankhurst
authors: Research Oncology, Division of Cancer Studies, King's College London, Guy's Hospital, London, UK. Electronic address: michael.douek@kcl.ac.uk.
authors: Michael
authors: M
authors: Douek
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000494:pharmacology*; D060526:Magnetic Fields; D060306:Magnetometry / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D021701:Sentinel Lymph Node Biopsy / Q000295:instrumentation / Q000379:methods; D013552:Swine
chemical_list: D003287:Contrast Media
keywords: Magnetic tracer; SLNB: magnetic technique; SPIO; Sentinel lymph node biopsy; Superparamagnetic iron oxide