Sentinel lymph node biopsy in patients with breast cancer using superparamagnetic iron oxide and a magnetometer

Abstract

This is the first study to use a magnetic tracer to identify sentinel lymph nodes in patients with breast cancer. This new technique may alter the role of radioisotopes with further refinement and experience.

160. Optimising magnetic sentinel lymph node biopsy in an in vivo porcine model

“…However, the false negative rate has been unacceptably high in studies of magnetic SLNB. Shiozawa et al [16] (would be good here to list how many patients, and maybe give this trial a name to -to be consistent with he other two) reported a false negative rate of 17 per cent using the magnetic technique and even the SentiMAG Multicentre Trial, [17] which was found to be non-inferior to the dual technique for SLN identification demonstrated a false negative rate of 8 per cent and 4 per cent for the magnetic and dual techniques respectively. The Central-European SentiMag Study [18] identified a lower false negative rate for the magnetic technique of 3 per cent versus 9 per cent for the standard radioisotope technique, inconsistent with the previous studies.…”

“…This means that the control of the performance of SLNB is directly within the hands of the operating surgeon who administers the magnetic tracer. All 3 published clinical studies [16][17][18] for the use of the magnetic technique injected the magnetic tracers after induction of general anaesthetic, periareolarly into the breast. Although the optimal timing of the magnetic tracer is not yet known, our results suggest that a pre-operative injection (4 hours or more prior to surgery) is likely to significantly improve the percutaneous magnetometer count and by doing so, improve the identification rate.…”

“…Once taken up by macrophages in the mononuclear phagocyte system of the lymphatics, the magnetic tracer is believed to be broken down and distributed across iron stores in the body. [15] The magnetic tracer can be detected intra-operatively using a handheld magnetometer [16][17][18].…”

“…[16][17][18] The largest trial, the SentiMAG Multicentre Trial, [17] recruited 161 patients (170 SLNB procedures) and found that the magnetic technique was non-inferior to the standard dual technique. This was confirmed by a later study, the Central-European SentiMag Study, [18] of 150 patients.…”

“…The higher false negative rate in the standard technique in this trial may be explained by the omission of blue dye, which is known to improve the SLN identification rate and lower the false negative rate of the dual technique. [7,19] All studies injected the magnetic tracer periareolarly after induction of general anaesthesia, with Shiozawa et al [16] injecting 1.6 mL Resovist (Bayer Health Care Osaka, Japan; 27.9 mg iron/mL), and the other two trials both using 2 mL Sienna+ (27mg iron/mL) diluted in 3 mL normal saline. [17,18] In order to make the magnetic technique a creditable alternative to the current dual technique, it is essential that we understand the behaviour of magnetic tracers from the injection site to distribution within the lymphatic basin.…”