Endoscopic Ultrasound in Guiding Local Resection and Ampullary Preservation of a High-Risk Periampullary GIST. - Spiel, Andrew; Patel, Ravi; Minter, Rebecca; Rahnemai Azar, Amir Ali; Agni, Rashmi; Bosch, Antonio; Gopal, Deepak (Case Reports in Gastrointestinal Medicine, 2020)