Magnetic Probe Guides Surgical Breast Lumpectomy

The Magseed implantable magnetic marker, a spiral shaped coil the size of a grain of rice, is first placed within the tumor in an outpatient procedure up to 30 days before the lumpectomy, allowing patients to return home before their operation.

During the lumpectomy, the Sentimag device is used to provide ultrasensitive, intuitive detection of the tumor, based on the principle of magnetic susceptometry. It does so by first generating an alternating magnetic field to transiently magnetize the iron oxide particles in the Magseed, and then detecting the tiny magnetic signature. Guided by the large two-color digital display and by an audible pitch variation, the surgeon can focus on the patient, not the device.

The Sentimag device boasts extremely high on-axis sensitivity for naturally intuitive and accurate node location. Sensitivity is adjustable in three settings from a control on the front panel, making it capable of detecting even minute quantities of magnetic material in the body. The Sentimag+Magseed combination device is a product of Endomag (Cambridge, United Kingdom), and has been approved by the U.S. Food and Drug Administration (FDA).

“Magseed is designed to guide surgeons using Sentimag to locate impalpable tumors for biopsy and has many advantages over wire and radioactive seed localization,” said device co-inventor professor Audrius Brazdeikis, PhD, a physicist at the University of Houston (UH, TX, USA). “Radiologists can place the Magseed magnetic markers up to 30 days in advance of surgery using X-ray or ultrasound guidance. This offers scheduling flexibility for surgeons and radiologists, as well as for patients, compared to wire-guided localization.”

Current lumpectomies require traditional guide wires inserted by a radiologist in a separate procedure prior to the procedure. The wires protrude from the patient’s breast, leading to potential discomfort and restricting the patient to the hospital environment. More critically, the protruding guide wires risk movement prior to surgery, requiring follow-up surgery in up to 55% of lumpectomy procedures.

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