Preoperative lymphoscintigraphy during lymphatic mapping for breast cancer: Improved sentinel node imaging using subareolar injection of technetium 99m sulfur colloid

Background: Preoperative lymphoscintigraphy has been recommended to confirm the successful uptake and direction of migration of radiotracer into senti nel nodes during lymphatic mapping for breast cancer. In addition, preopera tive lymphatic mapping may provide a visually useful aid to the relative lo cation of sentinel nodes within a nodal basin. One common method of breast lymphoscintigraphy involves injections of unfiltered technetium 99m sulfur colloid (Tc-99m-SC) directly into parenchymal tissues surrounding a tumor o r biopsy cavity (IP injection). Because of the many imaging failures and pr olonged imaging times of IP lymphoscintigraphy, the procedure has fallen in to disfavor by oncologic surgeons. The purpose of this study is to document the increased success rate of preoperative breast lymphoscintigraphy using a new anatomic site of injection, the subareolar lymphatic plexus (SA inje ction). Study Design: In the 12 months between December 1, 1998, and December 29, 1 999, 42 women with stage I and II breast cancer underwent preoperative lymp hoscintigraphy by either the IP (n = 12, December 1998 to May 1999) or SA ( n = 30, May 1999 to December 1999) route of injection. Both groups were inj ected with 1 mCi (37 MBq) of unfiltered Tc-99m-SC followed immediately by e xternal gamma-camera imaging. The success rate for preoperative sentinel no de imaging and the total imaging time were recorded in both groups. Results: The success rate of identifying a sentinel node by SA lymphoscinti graphy was 90% (n = 27 df 30 patients), compared with 50% (n = 6 of 12 pati ents) for IP lymphoscintigraphy (p = 0.009). The imaging time in the SA inj ection group was 34 +/- 16 minutes, which was 59% shorter than the imaging time in the IP injection group of 82 +/- 48 minutes (p < 0.001). No uptake into internal mammary nodes was seen in either group. Conclusions: Moving the site of injection of unfiltered Tc-99m-SC to the su bareolar lymphatic plexus (SA injection) increased the success rate of preo perative lymphoscintigraphy to 90%, compared with 50% using IP injections. Preoperative SA lymphoscintigraphy resulted in the rapid visualization of a xillary sentinel nodes within 30 minutes of SA injection, enabling a visual determination of the approximate number of sentinel nodes and their relati ve locations within the axilla. We conclude SA injection of unfiltered Tc-9 9m-SC is superior to IP injections when performing preoperative breast lymp hoscintigraphy and is a visually useful aid to lymphatic mapping for breast cancer. (J Am Coll Surg 2000;191:479-489. (C) 2000 by the American College ;of Surgeons).