Effects of different preparation methods and injection sites of 99Tcm-sulfur colloid on sentinel lymph node detection in breast cancer

Objective To prospectively investigate the optimal setting for sentinel lymph node biopsy (SLNB) in patients with breast cancer by comparing the effects of different preparation methods and injection sites of 99Tcm-SC in sentinel lymph node (SLN) mapping and detection.Methods Two batches of 99Tcm-SC were prepared by boiling for 3 min (radiotracer 1) and 5 min (radiotracer 2),respectively.Radioactive chemical purity (RCP) and size of colloid particles were measured at 10 min,1 h,2 h and 4 h after the preparation.One hundred and forty-seven patients with breast cancer were involved and randomly divided into 3 groups.Group A consisted of 40 patients with periareolar injection of radiotracer 1,group B of 40 patients with periareolar injection of radiotracer 2,and group C of 67 patients with peritumoral injection of radiotracer 2.Lymphatic mapping was performed for all patients using SPECT/CT preoperatively and blue dye was subdermally injected over the tumor.The detection rate of the axillary and internal mammary SLN was recorded.One-way analysis of variance,independent two-sample t and x2 tests were used to analyze the data.Results There was no significant difference of RCP between the two radiotracers at 10 min,1 h,2 h and 4 h after preparation (t =-0.267,-0.794,0.826 and-0.977,all P＞0.05).Compared with radiotracer 1,the percentage of particles smaller than 100 nm in radiotracer 2 reduced significantly ((73.72±2.36) ％ vs (65.25±3.56)％,t=6.436,P＜0.05) and the mean effective particle size was significantly larger ((45.27±6.42) nm vs (75.59t7.04) nm,t=7.315,P＜0.05).In groups A,B and C,the detection rate of the internal mammary SLN was 70.0％ (28/40),47.5％ (19/40) and 17.9％ (12/67),respectively,with significant difference (x2=29.525,P＜0.05).In groups A,B and C,the detection rate of the axillary SLN was 100％ (40/40),95.0％ (38/40) and 97.0％ (65/67),respectively,without significant difference (x2 =2.686,P＞ 0.05).Conclusion For SLNB of patients with breast cancer,the axillary and internal mammary SLN could be better detected by SPECT/CT lymphatic mapping using radiotracer prepared with a shorter boiling time,via periareolar injection,and combined with subdermal injection of blue dye.\r\n\r\nKey words: \r\nBreast neoplasms ;  Lymph nodes ;  Tomography, emission-computed, single-photon ; Tomography, X-ray computed;  Sulfur colloid