Performance of a Nonlinear Magnetic Handheld Probe for Intraoperative Sentinel Lymph Node Detection: A Phantom Study

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Surgical Navigation

Background:

• Sentinel lymph node detection is crucial for cancer staging.
• Magnetometry offers a non-radioactive alternative to traditional gamma probes.
• Advancements in probe technology aim to improve detection accuracy and proximity to tumors.

Purpose of the Study:

• To evaluate the performance of the DiffMag handheld probe (nonlinear magnetometry) for sentinel lymph node detection.
• To compare the DiffMag probe's performance against a gamma probe and a linear magnetometer (Sentimag®).

Main Methods:

• Probe performance was assessed using longitudinal and transverse distance measurements, and resolving power.
• Two different tracer volumes were used to simulate clinical conditions.
• A specialized phantom was developed for evaluating performance in a floor of the mouth (FOM) scenario.

Main Results:

• DiffMag handheld and Sentimag® showed comparable longitudinal detection, while the gamma probe detected 10x deeper.
• Transverse distances for small tracer volumes: DiffMag (13 mm), Sentimag® (11 mm), Gamma (51 mm).
• Resolving power (FWHM) for small tracer volumes: DiffMag (14 mm), Sentimag® (12 mm), Gamma (18 mm).

Conclusions:

• The DiffMag handheld probe is suitable for detecting SLNs in close proximity to primary tumors due to its high resolving power.
• Linear magnetometry (Sentimag®) demonstrated comparable performance to DiffMag.
• Gamma probes offer greater depth penetration but possess lower resolving power than the DiffMag handheld probe.