Dual modality image guided breast surgery using radiomarkers

Currently, the majority of lumpectomy and excisional biopsy procedures involving non-palpable breast lesions are performed using the wire localization technique. We are investigating dual modality surgical guidance as a means of overcoming many of the problems associated with wire localization. The technique uses a dual modality (digital mammography, breast scintigraphy) breast imaging system to place a marker composed of radiolabeled albumin into the lesion. In order to assist the surgeon in identifying a possible surgical path, a point will be marked on the surface of the breast that is geometrically closest to the lesion (the closest skin point, or CSP). In this paper we present the results of measurements of the localization and needle positioning accuracy of our system. We also describe the results of phantom measurements designed to determine the impact of mild breast compression on identification of the CSP. The localization accuracy was found to be within 0.4 mm for both X-ray and gamma imaging. On average, the errors in injection accuracy were 0.4, 0.6, and 0.5 mm for the x, y, and z dimensions, respectively. The result of the compressible phantom tests was that the path length from the lesion to the CSP determined under mild compression differed from that with the breast uncompressed by only ~10%. These results provide encouragement that we can accurately locate a lesion, inject the radiomarker into it, and identify a potential incision point whose distance from the lesion is within 10% of the shortest possible distance.