Pre-operative sentinel lymph node localization in breast cancer with superparamagnetic iron oxide MRI: the SentiMAG Multicentre Trial imaging subprotocol.
OBJECTIVE
Sentinel lymph node biopsy (SLNB) with a superparamagnetic iron oxide (SPIO) tracer was shown to be non-inferior to the standard combined technique in the SentiMAG Multicentre Trial. The MRI subprotocol of this trial aimed to develop a magnetic alternative for pre-operative lymphoscintigraphy (LS). We evaluated the feasibility of using MRI following the administration of magnetic tracer for pre-operative localization of sentinel lymph nodes (SLNs) and its potential for non-invasive identification of lymph node (LN) metastases.


METHODS
Patients with breast cancer scheduled to undergo SLNB were recruited for pre-operative LS, single photon emission CT (SPECT)-CT and SPIO MRI. T1 weighted turbo spin echo and T2 weighted gradient echo sequences were used before and after interstitial injection of magnetic tracer into the breast. SLNs on MRI were defined as LNs with signal drop and direct lymphatic drainage from the injection site. LNs showing inhomogeneous SPIO uptake were classified as metastatic. During surgery, a handheld magnetometer was used for SLNB. Blue or radioactive nodes were also excised. The number of SLNs and MR assessment of metastatic involvement were compared with surgical and histological outcomes.


RESULTS
11 patients were recruited. SPIO MRI successfully identified SLNs in 10 of 11 patients vs 11 of 11 patients with LS/SPECT-CT. One patient had metastatic involvement of four LNs, and this was identified in one node on pre-operative MRI.


CONCLUSIONS
SPIO MRI is a feasible technique for pre-operative localization of SLNs and, in combination with intraoperative use of a handheld magnetometer, provides an entirely radioisotope-free technique for SLNB. Further research is needed for the evaluation of MRI characterization of LN involvement using subcutaneous injection of magnetic tracer.


CONCLUSIONS
This study is the first to demonstrate that an interstitially administered magnetic tracer can be used both for pre-operative imaging and intraoperative SLNB, with equal performance to imaging and localization with radioisotopes.
1 MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands.
Joost J
http://orcid.org/0000-0003-4401-5768
JJ
Pouw
2 Department of Surgery, Medisch Spectrum Twente, Enschede, Netherlands.|3 Research Oncology, Division of Cancer Studies, King's College London, London, UK.
Maarten R
MR
Grootendorst
4 Department of Radiology, Medisch Spectrum Twente, Enschede, Netherlands.
Roland
R
Bezooijen
4 Department of Radiology, Medisch Spectrum Twente, Enschede, Netherlands.
Caroline A H
CA
Klazen
5 Department of Nuclear Medicine, Medisch Spectrum Twente, Enschede, Netherlands.
Wieger I
WI
De Bruin
2 Department of Surgery, Medisch Spectrum Twente, Enschede, Netherlands.
Joost M
JM
Klaase
6 Department of Radiology, University College London Hospital, London, UK.
Margaret A
MA
Hall-Craggs
3 Research Oncology, Division of Cancer Studies, King's College London, London, UK.
Michael
M
Douek
1 MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, Netherlands.
Bennie
B
Ten Haken
D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology*; D003287:Contrast Media; D003911:Dextrans; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D058185:Magnetite Nanoparticles; D008875:Middle Aged; D011300:Preoperative Care; D021701:Sentinel Lymph Node Biopsy
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C065507:ferumoxides