8th thematic workshop: International Symposium On Advanced Intraoperative Imaging of Radioisotopes and Presymposium workshop TOF PET

Dual-modality (digital mammography-breast scintigraphy) image-guided breast surgery using radiomarkers

6 Sept 2009, 18:15

15m

Hotel Baia delle Zagare

Symposium Session 7 (Continued)

Speaker

Patricia Judy (Department of Biomedical Engineering, University of Virginia)

Description

Currently, the majority of lumpectomy and excisional biopsy procedures involving non-palpable breast lesions are performed using the wire localization (WL) 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 and 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). A portable gamma camera, coupled with an optical digital mini-camera, will be used in the operating suite to assess the centricity of the radiomarker within the specimen, immediately after specimen removal. We present the results of pre-clinical validation 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 0.7 mm for x-ray imaging and within 1.2 mm for gamma imaging. On average, the errors in injection accuracy were 0.4, 0.7, and 0.6 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. Clinical trials are expected to begin in September 2009. Subjects will be enrolled in two groups. In group 1, we will compare the radiomarker technique with the current practice of WL among women who are not having sentinel lymph node biopsy (SLNBx) during their surgery. In group 2, we will compare the new technique to known success rates of WL, but among women who are also having SLNBx during their surgery. A total of 75 participants will be recruited; 55 in group 1, 20 in group 2.