1. School of Automation Science and Engineering, Xi’an Jiaotong University, Xi’an, China
2. Baidu Research, Beijing, China
3. Institute of Artificial Intelligence and Robotics, Xi’an Jiaotong University, Xi’an, Shanxi, China
4. Department of Ultrasound, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China