1. Department of Radiology, Massachusetts General Hospital, 55 Fruit St, WAC 240, Boston, MA 02114.
2. Department of Radiology, Center for Ultrasound Research & Translation, Massachusetts General Hospital, Boston, MA.
3. Present affiliation: The Third Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China.
4. Department of Radiology, Institute for Technology Assessment, Massachusetts General Hospital, Boston, MA.