Objective: This study aims to assess the role of three-dimensional single-photon emission computed tomography (3D-SPECT/CT) in sentinel node (SN) identification, and to analyze the impact of such information on estimating metastases to SNs.
Background: Nodal status is a key factor for breast cancer. SN biopsy has been established as the alternative to routine axillary dissection these days. We investigated both the anatomical location of SNs demonstrated by our 3D-SPECT/CT system and the correlation to SN positivity.
Methods: Two hundred and twenty-three clinically node-negative patients underwent SN biopsy. All of the axillary structures, including SNs, were visualized by a SPECT/CT combined system after subcutaneous injection of (99m)Tc-phytate. By plotting the visualized SNs, the most frequent SN location 'Pedestal area (PA)' was designated.
Results: SPECT/CT detected (99m)Tc uptake in 217 cases (97.3%). 3D-SPECT/CT images visualized the accurate location of SNs in each case. In patients whose SNs were histopathologically negative (SN-), 228 (98.3%) SNs were found in the PA, and 4 (1.7%) were in other zones. In those with histopathologically positive SNs (SN+), 65 (78.3%) SNs were in the PA and 18 (21.7%) were outside it. The difference in SN distribution (i.e., in or out of the PA) between SN+ and SN- patients was statistically significant (p<0.001, chi-square test).
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 the PA may suggest SN positivity, reflecting failure of the lymphatic drainage systems.