1. Department of Ultrasound (Q.X., L.X.), Nanchong Central Hospital, The Second Clinical Medical College, North Sichuan Medical College, North Sichuan Medical University, Nan Chong, Peoples Republic of China.
2. Department of Cardio-Thoracic Surgery (W.Y.), Nanchong Central Hospital, The Second Clinical Medical College, North Sichuan Medical College, North Sichuan Medical University, Nan Chong, Peoples Republic of China.