Stereoscopic scintigraphic imaging of breast cancer sentinel lymph nodes

Lymphoscintigraphy is used preoperatively to identify sentinel lymph nodes (SLNs). Conventional planar scintigraphy cannot provide three-dimensional(3D) information for SLN biopsy. We applied stereoscopic imaging to preoperative lymphoscintigraphy to obtain 3D information and evaluated its usefulness.

Forty-four clinical stage I breast cancer patients (1 male, 43 females; age, 59.4+/-11.4 years) were enrolled in this study. Three hours after the injection of Tc-99m, 10 degrees of oblique images and routine anterior and lateral images were acquired. Anterior and lateral stereoscopic images were obtained in all studies, except for 2 patients; only lateral views were done for those. Two experienced radiologists enumerated the visualized hot nodes.

Stereoscopic imaging delineated more hot axillary lymph nodes compared to routine planar imaging in 8 of 42 patients (19.0%) on anterior view, 5 of 44 patients (11.4%) on lateral view, and 11 of 44 patients (25.0%) on either the anterior or lateral view. Statistically significant differences were observed between stereoscopic and routine planar imaging method on the anterior (p=0.012) and the lateral views (p=0.043). The stereoscopic imaging provided 3D information and effectively separated closely located hot nodes that were viewed as one hot node on conventional planar images. Thirty-eight out of 42 cases (90%) with anterior stereoscopic images identified the same number or more axillary hot nodes compared with lateral stereoscopic images.

The stereoscopic imaging method could improve the preoperative identification of SLNs. This method is technically simple, and could be a powerful diagnostic tool for SLN imaging breast cancer.