Dartmouth Engineer - The Magazine of Thayer School of EngineeringDartmouth Engineer - The Magazine of Thayer School of Engineering

Making Breast-Conserving Surgery Safer and Better

By Anna Fiorentino
March 2016 • Thayer By Degrees: PhD

As breast conserving surgery (BCS) — removing malignant tissue while preserving the shape and appearance of the breast — becomes more common than mastectomy, researchers are finding new ways to determine a tumor's size, shape, and location to ensure all of the cancer is removed. Thus, Keith Paulsen, the Robert A. Pritzker Professor of Biomedical Engineering, engineering professor Venkataramanan Krishnaswamy, and Dartmouth-Hitchcock (D-H) general surgeon Richard Barth, and his team of D-H clinicians, are now using a GPS-type approach for supine image-guided breast conserving surgery to more accurately identify breast cancer tissue for resection.

The Dartmouth team's technique involves a first-ever combination of optical scanning and MRI — with the MRI like a map and the optical scan like a GPS arrow — eliminating a lot of guess work for the surgeon by providing real-time 3D images rather than using 2D images taken in the past.

"Supine MRI-guided breast surgery not only offers full 3D visualization of the tumor location, shape, and size in the OR but also provides projection of the tumor shape onto the breast surface, centered at the incision site," says Professor Krishnaswamy. "This level of detail and operating cues are simply not available to surgeons using currently available techniques."

With clinical trials underway, their approach is outperforming conventional — and often uncomfortable — wire techniques to identify and remove tumors, thus allowing women to safely keep more of their healthy breast tissue.

"We’re looking to replace wire localization, a pre-surgical procedure where a radiologist places a wire in a cancer that is not palpable, using a mammogram," says Paulsen. "The wire guides the surgeon during tumor resection but is not very effective and leads to a positive margin, meaning cancer cells are present at or near the surface of the excised breast lump, about 30 percent of the time."

The goal of this new cost-saving approach is to cut that positive margin rate in half, to 15% or less, while still reducing both the volume of tissue removed and the need for additional surgery. Instead of wire localization, Paulsen and his team acquire a breast MRI in the supine position, and register those images with optical scans of the breast recorded in the operating room during surgery to better guide the surgeon to the coordinates of the tumor.

Former engineering PhD student Matthew Pallone ’07, Th'13 worked on the project between 2010 and 2013. "I was responsible for developing the deformable image registration algorithm that matched preoperative supine MRI images with intraoperative optical scans of the patient. I also developed software to display the resulting 3D images to the surgeon, and allow him to manipulate the view using an optically tracked handheld stylus," says Pallone, adding that Krishnaswamy took over his work on the project when he graduated.

Image-guided supine breast surgery
The supine MRI-guided BCS procedure.

The team's original findings, "Supine Breast MRI and 3D Optical Scanning: A Novel Approach to Improve Tumor Localization for Breast Conserving Surgery," were published in 2014 in Annals of Surgical Oncology.

This effort is one of many developments underway at the Center for Surgical Innovation (CSI), a joint endeavor by D-H, Geisel School of Medicine at Dartmouth, and Thayer School offering integrated multi-modal 3D imaging, architectural engineering for safe co-location of animal studies, and prioritization of research activity over routine clinical care.

"At the CSI, we’re continuing to improve brain cancer treatment with fluorescence-guided surgery, exploring new frontiers in psychiatric research, and advancing spinal surgeries," says Paulsen.

Tags: engineering in medicine, faculty, innovation, research, students

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