Retroflexed endoscopic submucosal dissection of a lesion invading the pyloric ring, using a newly developed thin endoscope - Shichijo, Satoki; Kitagawa, Daiki; Asada, Yuya; Yoshii, Shunsuke; Uedo, Noriya; Ishihara, Ryu; Michida, Tomoki (Endoscopy, 2024)