Laparoscopic Probe for Sentinel Lymph Node Harvesting Using Magnetic Nanoparticles

Abstract

Sentinel lymph node harvesting is an essential step in the surgical treatment of a growing number of malignancies. Various techniques are available to facilitate this purpose. The present study reports a new laparoscopic technique for lymph node harvesting using magnetic nanoparticles containing a superparamagnetic iron-oxide core and dextran coating. This study assesses the clinical relevance of the prototype and provides input for further technological development on the way to clinical implementation. Methods: A laparoscopic differential magnetometer prototype was built, utilizing a nonlinear detection principle (differential magnetometry) for magnetic identification of lymph nodes. The iron content sensitivity, depth & spatial sensitivity, and angular sensitivity were analyzed to investigate clinical options. Results: The minimum detectable amount of iron was 9.8 μg at a distance of 1 mm. The detection depth was 5, 8, and 10 mm for samples containing 126, 252, and 504 µg iron, respectively. The maximum lateral detection distance was 5, 7, and 8 mm for samples containing 126, 252, and 504 µg iron, respectively. A sample containing 504 µg iron was detectable at all angulations assessed (0°, 30°, 60° and 90°). Conclusion: The laparoscopic differential magnetometer demonstrates promising results for further investigation and development towards laparoscopic lymph node harvesting using magnetic nanoparticles. Significance: The laparoscopic differential magnetometer facilitates a novel method for sentinel lymph node harvesting, which helps to determine prognosis and treatment of cancer patients.

Sentinel Lymph Node Techniques in Urologic Oncology: Current Knowledge and Application

“…During operation, tissues in which SPIONs are accumulated can be detected using a handheld magnetometer [33]. A recent study reported the development of a laparoscopic differential magnetometer probe, which showed promising results in terms of intraoperative SLN localization [34]. Although it is a relatively new method, the available data indicate its high efficiency in detecting SLNs.…”

Excitation coil for sentinel lymph node harvesting: design, digital twin and prototype

“…The complete LapDiffMag system consists of three main parts [11,14]: a set of excitation coils, a detection probe, and a control unit (Fig. 1).…”

“…The detection probe consist of two coils to detect the magnetic signal and two coils to compensate for the magnetic field generated by the excitation coil. The probe is designed to be operated by a laparoscopic surgeon and already tested with a clinical setting in mind [11]. The control unit consists of multiple parts: two power supplies, a transformer, a series resonant circuit, safety equipment, and a data acquisition system.…”

“…• Coil design necessary to create a magnetic field of 300 x 300 x 300 mm enabling SPION detection of ≥50 µg [11]. • Coil dimensions fitting mainstream operation room (OR) tables (average width of 520 mm), with a minimal thickness.…”

“…esophagus cancer, gastric cancer, colon cancer, prostate cancer, bladder cancer, and endometrial cancer [5][6][7][8][9][10]. A recently developed prototype (Laparoscopic Differential Magnetometer, in short LapDiffMag) is suitable to identify the magnetic tracer inside SLNs during clinical laparoscopic procedures [11].…”