Sentinel node identification in clinical stage Ia non-small cell lung cancer by a combined single photon emission computed tomography/computed tomography system

Objective A gamma probe can identify sentinel nodes before nodal dissection in the mediastinum but not in the hilum, owing to high radioactivity from primary tumors. We evaluated the utility of fused single photon emission computed tomography/computed tomography (SPECT/CT) images for the identification of sentinel nodes in the hilum for patients with clinical stage Ia non–small cell lung cancer. Methods Technetium-99m tin colloid was injected into the peritumoral region approximately 18 hours before surgery in 63 patients with clinical stage Ia non–small cell lung cancer. On the morning of the operation, approximately 16 hours after administration of tin colloid, sentinel nodes were identified by fused SPECT/CT; this was followed by intraoperative sentinel node identification in the dissected lymph nodes by gamma probe. Because the gamma probe is a standard method for sentinel node identification, the sensitivity of fused SPECT/CT images was examined on the basis of the data of the gamma probe. Results Fused SPECT/CT images could identify sentinel nodes at segmental and lobar lymph nodes with a sensitivity of 0.87 and 0.74, both of which were significantly higher than 0.40 in the mediastinum ( P P = .012, respectively). In 5 patients with pathologic N1 or N2 disease, both SPECT/CT and the gamma probe could identify sentinel nodes with metastases. Conclusions SPECT/CT could identify sentinel nodes of the hilum especially in segmental and lobar lymph nodes but not in the mediastinum. Because the gamma probe can identify sentinel nodes before nodal dissection in the mediastinum but not in the hilum, a combination of SPECT/CT and the gamma probe can be used to identify sentinel nodes before nodal dissection in both the hilum and the mediastinum, which will enable sentinel node navigation surgery in non–small cell lung cancer.