Bauke Anninga, Presenter: Nothing to Disclose

Samantha White, Abstract Co-Author: Nothing to Disclose

Paul Malcolm MRCP, FRCR, Abstract Co-Author: Speaker, General Electric Company

Joost Klaase, Abstract Co-Author: Nothing to Disclose

Bennie ten Haken PhD, Abstract Co-Author: Nothing to Disclose

Suzan Vreemann, Abstract Co-Author: Nothing to Disclose

Roland Bezooijen MD, Abstract Co-Author: Nothing to Disclose

Marc Moncrieff, Abstract Co-Author: Nothing to Disclose

Margaret Anne Hall-Craggs MD, Abstract Co-Author: Nothing to Disclose

Michael Douek MD, Abstract Co-Author: Nothing to Disclose

Sentinel lymph node biopsy (SLNB) in melanoma is currently performed using radioisotope and blue dye injections. We recently developed a novel magnetic technique for SLNB using a superparamagnetic iron-oxide (SPIO) tracer and a hand-held magnetometer for sentinel lymph node (SLN) localisation. The aim of this study was to assess the ability of magnetic resonance imaging (MRI) to identify lymphatic tracts and the SLN pre-operatively in patients with extremity melanoma, following administration of an SPIO tracer.

Patients with primary cutaneous melanoma scheduled for SLNB, and clinically AJCC stages IB-IIC, were recruited into the MRI sub-protocol of the MELAMAG Trial. SLN localisation was performed after administration of radioisotope (99mTc) and SPIO tracer (Sienna+, Endomagnetics Ltd.) with lymphoscintigraphy and MRI, respectively. For MRI localisation, pre-injection T1-weighted and T2-weighted (T2W) turbo-spin echo scans were followed by an intradermal injection of magnetic tracer and local massage at the injection site. T2W scans were repeated 15 minutes post-injection. Intra-operatively the magnetometer (SentiMag, Endomagnetics Ltd.) was used to localise the SLN(s), followed by the gamma probe and blue dye. Pre-operative lymphoscintigraphy was compared to pre-operative MRI by two independent radiologists.

Five patients with extremity melanoma (4 lower, 1 upper) were recruited. In all cases MRI+SPIO tracer identified the same number and sites of lymphatic drainage compared to lymphoscintigraphy. In 4 cases MRI and lymphoscintigraphy showed identical numbers of lymphatic channels. In 3 cases the total number of SLNs identified was the same for both imaging modalities.

SLN localisation with MRI in melanoma using a novel magnetic tracer is feasible. Pre-operative localisation correlates well with intra-operative findings. Additional evaluation is needed in larger and more challenging (including head, neck and truncal primary melanoma) cohorts of patients.

This novel approach of MRI with an SPIO tracer can provide high resolution, pre-operative SLN localisation without the use of radiation.

Anninga, B, White, S, Malcolm, P, Klaase, J, ten Haken, B, Vreemann, S, Bezooijen, R, Moncrieff, M, Hall-Craggs, M, Douek, M, Sentinel Lymph Node Localisation in Melanoma Using a Novel Magnetic Tracer for Magnetic Resonance Imaging.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003331.html