CT Based Lymphatic Mapping and Localization – A New Method To Detect Sentinel Lymph Node in Breast Cancer Patients.

Abstract

Abstract Background: Sentinel lymph node biopsy in breast cancer patients has not been extensively accepted in mainland China. The main reason is that radioisotope tracer is not available in many hospitals. The objective of this study is to explore CT based lymphatic mapping and localization. The accuracy will be evaluated comparing SLN found by CT with those found by isotope and blue dye.Methods: 18 breast cancer patients who diagnosed by core needle biopsy or excisional biopsy underwent CT scan to locate the SLN before SLNB at the same day of surgery. When CT examination performed, those patients were in supine position, with the arms stretched upward but bent at the elbow with the hands at the side of the cranium which similar to the surgical position. After local anesthesia, 2mL of iopamidol was injected subcutaneously to the peritumoral and peri-areolar areas followed by gentle massage for about 1 minute. Contiguous 2-mm-thick CT images that included the breast and axilla were obtained prior to administration of the contrast agent. After 3D CT reconstruction, the SLN was identified as the most inferiorly visible nodule in the axilla connected to the lymphatic vessel on the CT imaging monitor. A professional intervention doctor punctured the defined lymph node guided by the CT monitor using the Breast Lesion Localization Needles (interv). The needle would stay in the patient's axilla until the surgery. All the lymph nodes including the CT defined one and which marked by methylene blue dye or 99mTc-sulfur colloid tracers were removed, which then would be tested by touch imprint cytology for the intraoperative diagnosis. Patients who had positive SLN would receive axillary dissection. We evaluated the new method by comparing lymph nodes defined by CT and traditional ways.Results: In this study, the success rate of SLNB was 100% (18/18). 15 of 18 patients (83.3%) showed the direct connection of SLN and lymphatic vessels draining from the injection sites on CT monitor successfully. 13 of 15 patients' SLN localization corresponded well with SLN identified by the traditional SLN mapping. Of the 40 SLNs in 15 patients, 7 SLNs in 3 patients were positive and received the ALND. These 7 SLNs were all clearly visualized on CT monitor. Among 15 SLNs (in 15 patients) punctured by needles, 13 SLNs had the highest radioactivity by DGP-guided probe and 12 are blue dye–stained. All of the 15 SLNs had radioactivity or blue stained. None of these 18 patients showed any adverse events during or after CT examination and surgery. With the assistant of CT location, the mean time of SLNB had been shortened from 20 mins to 16 mins.Conclusion: Comparing with usual tracing method, CT guided axillary SLN mapping and localization showed good specificity and gave concordant results in locating sentinel lymph nodes. These results suggest that CT guided localization would be a valuable tool for identify sentinel lymph nodes in breast cancer patients. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1035.