1. Family Health Centers of San Diego, San Diego, California, USA;
2. Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA;
3. Department of Gastroenterology/Hepatology, Henry Ford Health, Detroit, Michigan, USA;
4. Division of Gastroenterology and Hepatology, Veterans Affairs Palo Alto Health Care System and Stanford University School of Medicine, Palo Alto, California, USA;
5. Division of Gastroenterology and Hepatology, University of Virginia, Charlottesville, Virginia, USA;
6. Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Chicago Medical Center, University of Chicago, Chicago, Illinois, USA.