The clinical study of character types of sentinel lymph nodes in patients with breast cancer in lymphatic contrast enhanced ultrasound

Objective To evaluate the diagnostic efficiency in differential diagnosis for breast sentinel lymph nodes, and to analyze the imaging characteristics of involved breast sentinel lymph node in lymphatic contrast enhanced ultrasound. Methods Sixty-one patients suspected with breast cancer from May 2017 to March 2019 in Shanghai General Hospital, Shanghai Jiao Tong University were included in the study. Ultrasound contrast agent was injected subcutaneously, and axillary lymph nodes were displayed under contrast enhanced ultrasound mode. The longitudinal diameter (anteroposterior diameter), transverse diameter, longitudinal/transverse ratio and the distance from skin surface were measured. Five types were concluded according to the imaging characteristics in lymphatic contrast enhanced ultrasound: typeⅠ, uniform enhancement; type Ⅱ, ring-shape enhancement; type Ⅲ, ununiform enhancement; type Ⅳ, regional filling defect; type Ⅴ, total filling defect. Sentinel lymph nodes were guided by wire guides and verified in pathology after excision in the operation. Results The detection rate of sentinel lymph nodes was 95.08% (58/61). Seventy-seven lymph nodes, including 21 involved nodes and 56 uninvolved nodes were detected by lymphatic contrast enhanced ultrasound in 58 patients. The longitudinal diameters and transverse diameters of involved lymph nodes were larger than those of uninvolved ones (P=0.001, 0.003). When type Ⅳ(regional filling defect) and type Ⅴ(total filling defect) were classified as involved, the sensitivity, specificity, positive-predictive value, negative-predictive value, accuracy and the area under ROC curve of predicting sentinel lymph node metastases were 85.71%, 96.43%, 90.00%, 94.70%, 93.51% and 0.911, respectively. Conclusions Lymphatic contrast enhanced ultrasound reaches a high diagnostic efficiency in qualitative analysis of breast sentinel lymph nodes. Regional filling defect and total filling defect are the imaging characteristics of involved sentinel lymph nodes in lymphatic contrast enhanced ultrasound. Key words: Contrast-enhanced ultrasound; Breast cancer; Sentinel lymph node; Differential diagnose; Diagnostic efficiency