Magnetic Resonance Sentinel Lymph Node Imaging and Magnetometer-Guided Intraoperative Detection in Penile Cancer, using Superparamagnetic Iron Oxide Nanoparticles: First Results.

In penile cancer, lymph node (LN) metastasis is the main known prognostic factor that affects survival. Inguinal sentinel LN (SLN) dissection (sLND) using radioactive marking is recommended by the European Association of Urology guidelines to evaluate the nodal status in clinically node-negative penile cancer (cN0; ≥pT1, G2). Dependence on radioisotopes limits the application of this procedure to small parts of the developed world, and imposes restrictions on hospital logistics. To overcome these issues, SLN visualization using magnetic resonance imaging (MRI) and magnetometer-guided detection after intraprostatic injection of superparamagnetic iron oxide nanoparticles (SPION) has been successfully applied in prostate cancer. Here, we present the first results of magnetic sLND in penile cancer. After peritumoral SPION injection, MR SLN imaging and magnetometer-guided sLND were performed in one cN0 penile cancer patient. Another patient underwent magnetometer-guided sLND only. In the first case, 5 SLNs could be visualized on MRI and intraoperatively detected by magnetometer-guided sLND. In the second patient, 3 SLNs could be detected by magnetic sLND. Neither patient exhibited adverse events attributable to SPION-injection. In conclusion, SPION-guided SLN identification using MRI and a handheld magnetometer is feasible and could provide a radiation-free technique for SLN identification in penile cancer. For further clarification, a multicenter study should be carried out.