Interdisciplinary Initiatives Program Round 8 - 2016

Bruce Daniel, Radiology
Ellen Kuhl, Mechanical Engineering
Brian Hargreaves, Radiology

This year, an estimated 41,000 breast cancer patients in the United States will undergo repeat surgery because of concern that there may be residual tumor remaining in their breast after their initial lumpectomy. These repeat surgeries are costly. They delay the onset of adjuvant chemotherapy and radiation. They may unnecessarily disfigure the breast if excessive tissue is removed. Lastly, they substantially increase patient anxiety. These repeat surgeries happen because the surgeon is unable to see or feel the full extent of tumor during the initial lumpectomy, even when assisted by mammograms and pre-operative guide wires. To address this, our breast radiology & surgery research group has developed a prototype system that uses a novel “mixed-reality” platform from Microsoft called the “HoloLens” to fuse images of highly accurate, previously acquired 3D contrast-enhanced MRI with the actual patient’s breast. The surgeon uses the interactive HoloLens tool to virtually interrogate her patient’s breast, and see the full extent of tumor right before surgery. Based on responses from numerous surgeons, we believe mixed-reality has potential to transform how ~170,000 lumpectomies are performed each year in the US. But our prototype system has one major limitation: it assumes the breast is rigid - it cannot provide accurate information once surgery begins, and the shape of the breast changes. Support from Bio-X will enable us to address this: we have formed a new partnership with Mechanical Engineers at Stanford who are experts in continuum mechanics of human tissues – the study of how tissues deform under mechanical stress. The fundamental hypothesis is that biomechanics can accurately model how the internal breast tissues are deforming during surgery based on changes in the position of skin features. The work will require very tight collaboration between our groups: the mechanical models will be based on 3D maps of tissue composition provided by various MRI sequences (i.e. “multiparametric MRI”); similarly, the needs of these models will inform how the MRI sequences will be performed. Validated models will then be integrated back into the HoloLens display system so that it is capable of accurately displaying tumors in the breast even as surgery proceeds. Ultimately, mixed-reality technologies have great potential to change surgery by melding patients and their images. This Bio-X IIP proposal will enable us to develop a pivotal technology on the path toward that vision: robust methods that remain accurate despite changes in the configuration of non-rigid tissues.