245 Preoperative MRI and magnetometer-guided intraoperative sentinel lymph node detection with superparamagnetic iron oxide nanoparticles in patients with vulvar cancer – a feasibility study (POSVUC Pilot)

Introduction/Background Sentinel lymph node (SLN) biopsy is a routine procedure for nodal staging in early vulvar squamous cell carcinoma (VSCC). To rule out metastasis, most preoperative imaging techniques are inferior to the invasive SLN biopsy guided by Tc99m lymphoscintigraphy and blue dye. An alternative could be the superparamagnetic iron-oxide (SPIO) tracer with nanoparticles in combination with magnetic resonance imaging (MRI), which is under development in breast cancer surgery. This feasibility study aim is to evaluate whether SPIO-MRI can potentially substitute the routine dual technique in pre-and intraoperative SLN localization. Secondary, to assess if SPIO-MRI can predict lymph node status in comparison to ultrasound of the groin and histopathological analysis. Methodology This ongoing trial will include 20 patients with VSCC scheduled for the SLN procedure at Sahlgrenska University Hospital, a national vulvar cancer center in Sweden. A preoperative routine ultrasound of the groins is followed by a SPIO-MRI. Detection of SLNs with magnetometer will be compared with the dual technique at surgery and presented as percentage of correlation. Sensitivity and specificity to detect SLN status between SPIO-MRI, ultrasound and histopathological analysis will be calculated. Results Twelve out of 20 women have been included, of which eight underwent a preoperative ultrasound and 10 an MRI of the groins. The SPIO dosage has been continuously evaluated to avoid MRI artefacts without compromising intraoperative magnetic detection of the SLN. A high tracer and MRI/lymph scintigraphy correlation have been found. Two women were found to have positive nodes, one with micrometastasis and one with macrometastasis of the groins, the latter detected by MRI, but not by ultrasound. Conclusion The magnetic lymph node procedure appears to correlate well with the intraoperative standard technique of SLN detection in vulvar cancer, as well as the preoperative detection of SLNs. The inclusion of more patients will proceed. Disclosures No disclosures.