School of Medicine Shandong University Jinan 250100 Shandong Province China;
Department of Ultrasound Beijing Shijitan Hospital affiliated to Capital Medical University Beijing 100038 China;
Department of Breast Surgery Beijing Shijitan Hospital affiliated to Capital Medical University Beijing 100038 China;
Department of Radiology The Second Hospital of Shandong University Jinan 250100 Shandong Province China;
Breast tumor; Ultrasonography; Contrast agents; Feature exploration; Diagnosis; Non-mass-like lesions;