RF Technology Devised to Localize Breast Tumors

For women undergoing breast cancer surgery, a localization wire is inserted into the breast through a needle to help mark the location of a tumor or benign mass on the day of surgery. For the patient, it is one another phase of what is an already painful and emotionally distressing process.

For a team of University of Wisconsin (UW)-Madison (USA) engineers and clinicians, this was an opportunity to develop a solution that is technologically refined, precise, and patient-centric. The investigator’s solution—a system that replaces the localization wire with a radiofrequency tag that helps the surgeon track the tumor’s location with greater precision—was the motivation for the researchers to establish the company Elucent Medical (Madison, WI, USA).

Dan van der Weide, a UW-Madison professor of electrical and computer engineering and one of Elucent’s founders, discusses the localization wire with palpable dismay. “It’s not something I think I would wish on anyone,” he said. “It’s stressful to place this wire on the day of a difficult surgery.”

Moreover, from an engineer’s perspective, the localization wire creates all kinds of hurdles to removing a tumor while maintaining as much healthy breast tissue as possible. For instance, the wire is inserted when the breast is compressed in a mammogram machine or under ultrasound guidance. If the mass or cancer is in the center of the breast, there may be a distance of more than two inches from that mass to the skin where the wire must exit. “I get a 2D [two-dimensional] picture of where the wire is in the breast, but it’s a 3-D event—and requires piecing the pictures together to find the cancer,” said Elucent’s Lee Wilke, director of the UW Health Breast Center and a UW-Madison professor of surgery.

The localization wire, at best, is simply marking one point along the boundary of the tumor, leaving it to the surgeon to determine out the rest of the picture. “The wire can be very biased, because it only comes from one direction,” Dr. Wilke noted. “It’s been this way for more than 30 years.”

One possible workaround is to implant a small radioactive pellet at the location of the tumor, then track it with a handheld radiation detector. However, Dr. Wilke emphasized that cancer clinicians are already exposed to a lot of radiation, and putting them at even more risk clearly is not a good idea.

Radiofrequency identification (RFID), a widespread technology with many applications in tracking and communication, offers a compromise. The solution depends on expanding the scope of a relatively simple technology with many everyday uses. A pet animal that has been “microchipped” has been implanted with an integrated circuit that uses RFID technology to transmit identifying information when scanned. One of Elucent’s key technical challenges is to create a new kind of RFID tag that will better modify the technology to localization purposes.

“There’s no facility for saying, look, the tag is precisely 3.5-cm deep and over 1 cm from where your reader is,” Prof. van der Weide stated. He is now working on designing a coil array that can wrap around an RFID tag and provide more precise location data via a wand-like reader in the operating room.

Surgeons such as Dr. Wilke would approve a practical option to the localization wire, provided it is easy to learn and use, and Prof. van der Weide noted that Elucent’s solution to the problem is not really all that complex. In fact, the device makes the treatment process less expensive and logistically simpler. Because the tag could be implanted while the patient undergoes a biopsy, it essentially eliminates not only the wire but also the entire localization wire-implant procedure, which the company reported can save up to USD 2,500 per patient.

Before Elucent can replace the localization wire with what is basically a small metal pellet, the engineers will modify the object’s design and seek regulatory approval. But the team is confident that stepping back and rethinking an outdated procedure will elevate the standards of care and dignity for breast cancer patients. “A lot of medical procedures evolved out of an immediate need, and common sense and simplicity weren’t at the forefront,” Prof. van der Weide commented.

Related Links:
University of Wisconsin-Madison
Elucent Medical