[1] Akita Univ, Dept Gastroenterol, Grad Sch Med, 1-1-1 Hondo, Akita, Akita 0108543, Japan
[2] Hirosaki Univ Hosp, Div Endoscopy, Aomori, Japan
[3] Aomori City Hosp, Dept Gastroenterol, Aomori, Japan
[4] Iwate Med Univ, Sch Med, Div Gastroenterol & Hepatol, Dept Internal Med, Morioka, Iwate, Japan
[5] Iwate Prefectural Ofunato Hosp, Dept Internal Med & Gastroenterol, Ofunato, Iwate, Japan
[6] Akita City Hosp, Dept Gastroenterol, Akita, Japan
[7] Akita Red Cross Hosp, Digest Dis Ctr, Akita, Japan
[8] Ogachi Cent Hosp, Dept Gastroenterol, Akita, Japan
[9] Tohoku Univ, Grad Sch Med, Div Gastroenterol, Sendai, Miyagi, Japan
[10] Miyagi Canc Soc, Canc Detect Ctr, Sendai, Miyagi, Japan
[11] Yamagata Univ Hosp, Div Endoscopy, Yamagata, Japan
[12] Yamagata Prefectural Cent Hosp, Dept Gastroenterol, Yamagata, Japan
[13] Fukushima Med Univ Hosp, Dept Endoscopy, Fukushima, Japan
[14] Iwase Gen Hosp, Dept Gastroenterol, Fukushima, Japan
[15] Fukushima Med Univ, Dept Gastrointestinal Tract Surg, Sch Med, Fukushima, Japan
[16] Hirosaki Univ, Dept Gastroenterol, Grad Sch Med, Aomori, Japan
[17] Yamagata Univ, Dept Gastroenterol, Fac Med, Yamagata, Japan
[18] Fukushima Med Univ, Dept Gastroenterol, Sch Med, Fukushima, Japan