Diagnostic value of nuclear medicine modalities for the detection of sentinel lymph nodes in patients with breast cancer

Purpose of the study. To determine and compare the diagnostic efficacy of planar scintigraphy, SPECT (including SPECT / CT) and intraoperative gamma probe radiometry in the detection of sentinel lymph nodes (SLN) in patients with breast cancer. Material and Methods. The study included 200 patients with diagnosed breast cancer who underwent SLN biopsy in the period 2020-2021. To identify SLNs, all patients underwent lymphoscintigraphy with a 99mTc-labeled colloidal radiopharmaceutical one day before surgery. Planar lymphoscintigraphy was performed on 200 patients included into the study, 181 underwent examination in the volume of SPECT or SPECT/CT (147 and 34 studies, respectively). The SLN was detected intraoperatively using a portable gamma probe (n=200). Subsequent histological examination determined the presence of lymphoid tissue and the status of the removed SLN. Results. SLN were detected in a comprehensive study (planar and tomographic studies) in all 200 patients studied (100 %), while planar scintigraphy did not visualize any SLN in 6 (3 %) cases, but they were determined during examination in tomographic mode. Also, in some cases, additional SLN were determined during tomography, which were not considered in the planar study. In 95 % of cases, SLN were localized in the axillary region. All non-axillary SLNs were identified on tomograms. The sensitivity of SPECT for SLN detection was 100 % (CI 98.0-100 %), which was higher than the sensitivity of planar scintigraphy and gamma probe (97.0 %, CI 96.5-97.4 % and 97.0 %, CI 96.1-97.4 %, respectively). The PPV values were also high (99.5 %, CI 99.0-100 % for planar scintigraphy, 99.5 %, CI 98.6-100 % for gamma probe and 98.3 %, CI 95.2-99.7 % for SPECT. Conclusion. Nuclear medicine imaging of SLN with lymphotropic radiopharmaceuticals in patients with breast cancer is an effective and reliable method of navigation during surgery to perform a biopsy. SPECT and SPECT/CT can identify more lymph nodes than planar scintigraphy, improving their anatomical localization, and reducing the false negative rate. The diagnostic performance of SPECT/CT and SPECT is believed to be superior to that of planar lymphoscintigraphy and intraoperative navigation in detecting SLN.