Handheld magnetic probe with permanent magnet and Hall sensor for identifying sentinel lymph nodes in breast cancer patients

Abstract

The newly developed radioisotope-free technique based on magnetic nanoparticle detection using a magnetic probe is a promising method for sentinel lymph node biopsy. In this study, a novel handheld magnetic probe with a permanent magnet and magnetic sensor is developed to detect the sentinel lymph nodes in breast cancer patients. An outstanding feature of the probe is the precise positioning of the sensor at the magnetic null point of the magnet, leading to highly sensitive measurements unaffected by the strong ambient magnetic fields of the magnet. Numerical and experimental results show that the longitudinal detection length is approximately 10 mm, for 140 μg of iron. Clinical tests were performed, for the first time, using magnetic and blue dye tracers—without radioisotopes—in breast cancer patients to demonstrate the performance of the probe. The nodes were identified through transcutaneous and ex-vivo measurements, and the iron accumulation in the nodes was quantitatively revealed. These results show that the handheld magnetic probe is useful in sentinel lymph node biopsy and that magnetic techniques are widely being accepted as future standard methods in medical institutions lacking nuclear medicine facilities.

Multicenter clinical trial on sentinel lymph node biopsy using superparamagnetic iron oxide nanoparticles and a novel handheld magnetic probe

“…The Sentimag system uses an electromagnet coil and requires a large power supply. 16 On the other hand, our handheld magnetometer has a permanent magnet and a Hall magnetic sensor. We were able to merge the probe body and the driving circuit, achieving a cordless device.…”

“…The prototype of the new magnetic probe was further improved and evaluated in 6 patients with breast cancer, which yielded promising results. 16 We have used the handheld magnetic probe prototype developed previously, but it is now cordless, weighs only 108 g, and is very compact and easy to use. Here, we present the results of a multicenter clinical study that evaluated the use of the Resovist magnetic particles and the newly developed handheld magnetic probe for SLNB, and we compared the detection rate of this method to the standard SLNB method (radioactive tracer 99m Tc and a blue dye).…”

“…A new original magnetic probe that differs from the Sentimag for intraoperative identification of magnetic nanoparticles in SLNs has been developed. This probe uses a static magnetic field from a permanent magnet, making it compact and easy to use …”

“…Shiozawa et al performed SLN biopsies for breast cancer using Resovist and a prototype of the new magnetic probe, and they demonstrated a 77% detection rate. The prototype of the new magnetic probe was further improved and evaluated in 6 patients with breast cancer, which yielded promising results . We have used the handheld magnetic probe prototype developed previously, but it is now cordless, weighs only 108 g, and is very compact and easy to use.…”

“…This probe uses a static magnetic field from a permanent magnet, making it compact and easy to use. 16…”