Dr. Choi is a clinical chair professor of radiology at Chung-Ang University medical center and a professor emeritus of Seoul National University, College of Medicine. He is also a former president of The Korean Society of Radiology (KSR), Korean Society of Ultrasound in Medicine (KSUM), Korean Society of Abdominal Radiology (KSAR), Asian Federation of Societies of Ultrasound in Medicine and Biology (AFSUMB), first vice president of World Federation of Ultrasound in Medicine and Biology (WFUMB). He is also past president of the Asian Oceanian Society of Radiology (AOSR) and the Asian Society of Abdominal Radiology (ASAR),.and member of executive committee of International Society of Radiology (ISR), international cooperation committee of Radiological Society of North America (RSNA), and International Society for Strategic studies in Radiology (ISSSR). He is honorary member of 10 international and regional societies including RSNA. He is also honorary fellow of American college of Radiology (ACR), American Institute of Ultrasound in Medicine (AIUM) and European Society of Gastrointestinal and Abdominal Radiology (ESGAR). Dr Choi is a world renowned abdominal radiologist, particularly in the field of hepatobiliary imaging. He is a tireless and prolific clinical and scientific researcher, devoted teacher, and an outstanding clinician. Dr. Choi has authored more than 500 scientific papers and 31 textbooks, and presented more than 380 lectures internationally.