Redefining the clinical axillary lymph node staging using SPECT/CT in early breast cancer during SLNB

Abstract

BackgroundSPECT/CT imaging can provide information on axillary nodal morphology, number, and status of axillary levels, along with information on primary tumor morphology, mediastinum, and lungs that assesses nodal status beyond localization. The current study aims to evaluate the feasibility of SLNB with SPECT/CT for reporting nodal information in terms of morphology, number, and axillary levels that assess nodal staging. Ninety consecutive patients with early breast cancer were included. Thirty-seven MBq (1 mCi) of Tc99m nanocolloid was used. SPECT/CT followed PS. Nodal morphology, number, and axillary levels of sentinel and non-SLNs were reported along with their localization through a gamma probe.ResultsThe mean population age was 54.5 ± 3 years. PS visualized 152 SLNs in 79 patients (success rate of 88%), and SPECT/CT showed 178 SLNs in 84 patients (93% success rate). SPECT/CT showed 90% of SLNs localized at axillary levels I & II, with 10% at the rest of the nodal areas. Out of total surgically excised, 103/706 nodes were tumor positive, and 603/706 nodes were histopathologically tumor-free. Out of 178 hot nodules, 40 showed morphologically abnormal nodes, including a few with more than one abnormal feature. The average scores in the characterization of nodal morphology for the two observers were 2.4 ± 0.71 and 2.53 ± 0.52, respectively, with a substantial agreement (k = 0.76).ConclusionsHybrid imaging with SPECT/CT defines axillary lymph nodes' level and morphological features. This additional information directs the surgeon to nodes not seen by planar imaging during SLNB and can help redefine the clinical axillary lymph node staging.