1. Department of Gastroenterology, National Institute of Medical Science and Nutrition Salvador Zubiran, Vasco de Quiroga 15, Belisario Domínguez Sección XVI, Tlalpan, Mexico City 14000, Mexico
2. Department of Radiology, National Institute of Medical Science and Nutrition Salvador Zubiran, Vasco de Quiroga 15, Belisario Domínguez Sección XVI, Tlalpan, Mexico City 14000, Mexico
3. Department of Internal Medicine, National Institute of Medical Science and Nutrition Salvador Zubiran, Vasco de Quiroga 15, Belisario Domínguez Sección XVI, Tlalpan, Mexico City 14000, Mexico