Potential advantage of studying preoperative sentinel node mapping with three-dimensional images by a hybrid single photon emission CT (SPECT)/CT system for breast cancer

Abstract

601 Background: Lymph node status is one of the key factors in determining the stage, appropriate therapy and outcome in patients with breast cancer. Accurate identification of sentinel nodes (SNs) has clinical importance for each patients before surgery. The purpose of this study was to assess the role of Single-photon emission computed tomography (SPECT)/CT lymphoscintigraphy in SN identification for patients with breast cancer, and to analyze the impact of such information on estimating metastases to SNs. Methods: Two hundred and twenty-three clinically node-negative patients were underwent SN biopsy between July 2002 and November 2006. CT and SPECT images were obtained after injection of subcutaneal 1mCi (99m)Tc-nanocolloid, allowing identification of SN. Target and non-target structures, including lymph nodes identified by SPECT, were drawn by SPECT/CT combined system, which was comprised of a two-detector SPECT system and a multiple-detector CT at the same platform. We compared the anatomical location of SNs demonstrated on the 3D SPECT/CT images and correlation to SN positivity. Results: SPECT/CT uptake was detected in 221 cases (99.1%). 3D SPECT/CT images visualized accurate localization of SNs in each cases. Total number of biopsied SNs were 315 , and the most frequent locations of SN were trapezoid area in the upper side of axilla. We defined this area as ‘Pectoral area (PA)’. In SN negative (SN-) patients, 228 (98.3%) SNs were found in PA, and 4 (1.7%) SNs were out of this area such as parasternal area. In SN positive (SN+) patients, 65(78.3%) SNs were in the PA, and 18(21.7%)SNs were out of PA ,respectively. Significant differences (p<0.01 ,chi-square test) were found in SNs distribution whether in or out of PA between SN+ and SN- patients. Conclusions: SN biopsy navigated by 3D-SPECT/CT can clarify the preoperative anatomical localization of SNs in patients with breast cancer. Atypical distribution of SNs out of PA may suggest SN positivity as a reflection of the failure of lymphatic drainage systems. No significant financial relationships to disclose.