Sentinel lymph node surgery in prostate cancer using magnetic particles

The current status and future prospects for molecular imaging-guided precision surgery

Molecular imaging technologies are increasingly used to diagnose, monitor, and guide treatment of i.e., cancer. In this review, the current status and future prospects of the use of molecular imaging as an instrument to help realize precision surgery is addressed with focus on the main components that form the conceptual basis of intraoperative molecular imaging. Paramount for successful interventions is the relevance and accessibility of surgical targets. In addition, selection of the correct combination of imaging agents and modalities is critical to visualize both microscopic and bulk disease sites with high affinity and specificity. In this context developments within engineering/imaging physics continue to drive the growth of image-guided surgery. Particularly important herein is enhancement of sensitivity through improved contrast and spatial resolution, features that are critical if sites of cancer involvement are not to be overlooked during surgery. By facilitating the connection between surgical planning and surgical execution, digital surgery technologies such as computer-aided visualization nicely complement these technologies. The complexity of image guidance, combined with the plurality of technologies that are becoming available, also drives the need for evaluation mechanisms that can objectively score the impact that technologies exert on the performance of healthcare professionals and outcome improvement for patients.

A complete magnetic sentinel lymph node biopsy procedure in oral cancer patients: A pilot study

OBJECTIVES

To assess the feasibility and merits of a complete magnetic approach for a sentinel lymph node biopsy (SLNB) procedure in oral cancer patients.

MATERIALS AND METHODS

This study included ten oral cancer patients (stage cT1-T2N0M0) scheduled for elective neck dissection (END). Superparamagnetic iron oxide nanoparticles (SPIO) were administered peritumorally prior to surgery. A preoperative MRI was acquired to identify lymph nodes (LNs) with iron uptake. A magnetic detector was used to identify magnetic hotspots prior, during, and after the SLNB procedure. The resected sentinel LNs (SLNs) were evaluated using step-serial sectioning, and the neck dissection specimen was assessed by routine histopathological examination. A postoperative MRI was acquired to observe any residual iron.

RESULTS

Of ten primary tumors, eight were located in the tongue, one floor-of-mouth (FOM), and one tongue-FOM transition. SPIO injections were experienced as painful by nine patients, two of whom developed a tongue swelling. In eight patients, magnetic SLNs were successfully detected and excised during the magnetic SLNB procedure. During the END procedure, additional magnetic SLNs were identified in three patients. Histopathology confirmed iron deposits in sinuses of excised SLNs. Three SLNs were harboring metastases, of which one was identified only during the END procedure. The END specimens revealed no further metastases.

CONCLUSION

A complete magnetic SLNB procedure was successfully performed in eight of ten patients (80% success rate), therefore the procedure seems feasible. Recommendations for further investigation are made including: use of anesthetics, magnetic tracer volume, planning preoperative MRI, comparison to conventional technique and follow-up.

Technetium-Radiolabeled Mannose-Functionalized Gold Nanoparticles as Nanoprobes for Sentinel Lymph Node Detection

Gold nanoparticles (AuNPs) are considered valuable nanomaterials for the design of radiolabeled nanoprobes for single-photon emission computed tomography (SPECT) imaging. Radiolabeled and functionalized AuNPs could improve lymphatic mapping by enhancing the radioactive signaling of individual particles in the sentinel node. In this study, an alternative method for functionalizing commercial AuNps with mannose is described. The chemical derivatization and biofunctionalization of AuNPs were performed with lipoic acid and mannose, respectively. Several levels of mannose were tested; the thiolate hydrazinonicotinamide-glycine-glycine-cysteine (HYNIC) molecule was also used for ^99mTc radiolabeling. Physicochemical characterization of this system includes U-V spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy, and transmission electron microscopy. The most stable nanoprobe, in terms of the aggregation, radiolabeling efficiency, and purity, was tested in a sentinel lymph node model in a rat by microSPECT/computed tomography (CT) imaging. The SPECT images revealed that ^99mTc-radiolabeled AuNPs functionalized with mannose can track and accumulate in lymph nodes in a similar way to the commercial ^99mTc-Sulfur colloid, commonly used in clinical practice for sentinel lymph node detection. These promising results support the idea that ^99mTc-AuNPs-mannose could be used as a SPECT contrast agent for lymphatic mapping.

Sentinel lymph node dissection in prostate cancer using superparamagnetic particles of iron oxide: early clinical experience

PURPOSE

Superparamagnetic nanoparticles of iron oxide (SPION) were shown to be non-inferior to standard radioisotope tracer in breast cancer and may be used as an alternative to identify sentinel lymph nodes (SLN). The aim of this study was to assess the feasibility of sentinel lymph node dissection (SLND) using SPION in prostate cancer and to evaluate its diagnostic accuracy.

METHODS

Twenty patients with intermediate- and high-risk prostate cancer were prospectively enrolled in 2016. After intraprostatic injection of SPION, SLND using magnetometer was performed the following day. Extended pelvic lymph node dissection (ePLND) was added as a reference standard test. The diagnostic performance of the test were evaluated, as well as the rate of in vivo detected SLN. Surgical times of SLND and ePLND were compared using paired two-sample t test.

RESULTS

In total, 97 SLN were detected with median 5 (IQR 3-7) per patient. Non-diagnostic rate of the procedure was 5%. In total, 19 nodal metastases were found in 5 patients, of which 12 were located in SLN. The sensitivity per patient for the whole cohort was 80% and per node 56%. If only patients with at least one detected SLN were considered, the sensitivity per patient and per node reached 100 and 82%, respectively. A median of 20 LNs (IQR 18-22) were removed by subsequent ePLND. Surgical times of SLND and ePLND differed significantly, with medians of 17 and 39 min, respectively (p < 0.001).

CONCLUSIONS

SLND with SPION is feasible and safe in prostate cancer and the diagnostic accuracy is comparable to the published results of radioguided procedures. In open surgery, SPION may be used as an alternative tracer with its main advantage being the lack of radiation hazard.