1. Department of Geriatrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
2. Chongqing Key Laboratory of Ultrasound Molecular Imaging, Ultrasound Department of the Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
3. Institute of Anorectal Diseases, North Sichuan Medical College, Nanchong 637000, China
4. Department of Anesthesiology, The Second Clinical College of North Sichuan Medical College, Nanchong Central Hospital, Nanchong 637000, China
5. State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, Chongqing Medical University, Chongqing 400010, China