Utility of single-photon emission tomography/computed tomography for sentinel lymph node localization in breast cancer patients.

Abstract

Sentinel lymph node (SLN) mapping is currently a routine technique in breast cancer management and preoperative scintigraphic imaging plays a crucial role in the process of SLN detection. The guidelines recommend performing planar acquisition and optional single-photon emission tomography/computed tomography (SPECT/CT) imaging. The aim of this study was to verify whether routine performing of SPECT/CT in addition to planar imaging increases the sensitivity of SLN detection in patients with early-stage breast cancer. The secondary aims were to compare radionuclide SLN imaging with intraoperative SLN detection and identify clinical and histopathological factors affecting the SLN detection rate. A total of 153 early-stage breast cancer patients underwent lymph node scintigraphy in the years 2007-2013. Breast cancer patients with staging T1-2N0M0 were included. Planar and SPECT/CT lymphoscintigraphy were performed on the day before the surgery. The data on presence or absence of SLN, their number and localization were recorded for both methods and compared with each other as well as with intraoperative blue dye staining and histopathological findings. SPECT/CT identified SLN in 119/153 and planar scintigraphy in 114/153 patients. Identification rates were 77.7 and 74.5%, respectively. Intraoperative lymph node assessment identified SLN in 76/126 cases with an identification rate of 60.3%. Identification rates for second echelon lymph node were 34.6% for hybrid imaging and 21.2% for planar scintigraphy. Statistical analysis did not yield a significant difference in diagnostic accuracy between these methods; however, the Wilcoxon signed-rank test showed that SPECT/CT significantly increases SLN identification rate compared with planar scintigraphy and intraoperative detection. Histopathological examination of excised SLN showed that 22 nodes were metastatic. SPECT/CT visualized all of these, whereas planar imaging and intraoperative lymph node detection procedure visualized 19 and 18, respectively. No clinical and histopathological factors affecting SLN detection rate were identified. Hybrid SPECT/CT lymphatic mapping yields a high SLN detection rate in patients with early-stage breast cancer and provides lymph node localization details. It identifies more SLN than planar imaging and intraoperative SLN detection. However, its limited superiority over the remaining two methods does not support its routine use for SLN localization. We suggest using SPECT/CT for SLN detection in case of equivocal planar imaging results.