THREE-DIMENSIONAL ULTRASOUND IN MARGIN EVALUATION FOR BREAST TUMOR EXCISION USING MAMMOTOME

Sonographic evidence of tumor removal by Mammotomr excision does not confirm histological
clearance. The operator finds it hard to determine if a malignant tumor has been fully removed, leaving a safe
margin in the direction of each border; that is, the spatial orientation during tumor retrieval is not well-established
by naked eye under sonographic guidance. We propose a computational imaging process to extract
reasonable tumor contour in pre- and postoperative data sets for sonographic guidance so that Mammotomr excision can help the operator to evaluate the surgical outcome. There were five tumors in the study, including
three benign and two malignant. The lesion of interest was delineated after 2-D examination was completed, then
it was analyzed with 3-D breast ultrasound (US). To give a reference point for correlations between pre- and
postoperative images, we used a marker tape pasted on the skin within the transducer scanning area and then
the preoperative 3-D US images were obtained. Subsequently, 2-D breast US was applied during Mammotomr operation. After the Mammotomr procedures were finished, the postoperative 3-D US images were obtained;
thus, we gained two different data sets of 3-D US images that were used for later analysis for evaluating the
extension of postoperative margin status. From the results, the safe margin was not satisfactory in all directions,
because the minimum differences measured by the proposed algorithm were not large enough in all five cases,
and this was proved from two malignant mastectomy specimens. The experimental results representing this
inadequate Mammotomr excision can be visualized through the computer aid. The comparison of tumor
contour and excision margin may possibly be used for small malignant tumors in the future to improve the
breast-conserving surgery. (E-mail: dlchen88@ms13.hinet.net)