1. Center for Health Professions Education, Department of Medicine, Uniformed Services University of the Health Sciences , Bethesda, MD 20814, USA
2. Department of Surgery, Walter Reed National Military Medical Center/Uniformed Services University of the Health Sciences , Bethesda, MD 20889, USA
3. Department of Surgery, Naval Medical Center Portsmouth , Portsmouth, VA 23708, USA
4. 3D Medical Applications Center, Department of Radiology, Walter Reed National Military Medical Center , Bethesda, MD 20889, USA