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Dive into the research topics where Keijiro Sunada is active.

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Featured researches published by Keijiro Sunada.


Clinical Gastroenterology and Hepatology | 2004

Clinical outcomes of double-balloon endoscopy for the diagnosis and treatment of small-intestinal diseases.

Hironori Yamamoto; Hiroto Kita; Keijiro Sunada; Yoshikazu Hayashi; Hiroyuki Sato; Tomonori Yano; Michiko Iwamoto; Yutaka Sekine; Tomohiko Miyata; Akiko Kuno; Hironari Ajibe; Kenichi Ido; Kentaro Sugano

BACKGROUND & AIMS A specialized system for a new method for enteroscopy, the double-balloon method, was developed. The aim of this study was to evaluate the usefulness of this endoscopic system for small-intestinal disorders. METHODS The double-balloon endoscopy system was used to perform 178 enteroscopies (89 by the anterograde approach and 89 by the retrograde approach) in 123 patients. The system was assessed on the basis of the rates of success in jejunal and ileal insertion and the entire examination of the small intestine, diagnostic yields, ability to perform treatment, and complications. RESULTS Insertion of the endoscope beyond the ligament of Treitz or ileocecal valve was possible in all 178 procedures. It was possible to observe approximately one half to two thirds of the entire small intestine by each approach, and observation of the entire small intestine was possible in 24 (86%) of 28 trials. The source of bleeding was identified in 50 (76%) of 66 patients with GI bleeding, scrutiny of strictures was possible in 23 patients, and a tumor was examined endoscopically in 17 patients. Two complications (1.1%) occurred. Endoscopic therapies in the small intestine including hemostasis (12 cases), polypectomy (1 case), endoscopic mucosal resection (1 case), balloon dilation (6 cases), and stent placement (2 cases) were performed successfully. CONCLUSIONS Double-balloon endoscopy permits the exploration of the small intestine with a high success rate of total enteroscopy. The procedure is safe and useful, and it provides high diagnostic yields and therapeutic capabilities.


Gastrointestinal Endoscopy | 2002

Success rate of curative endoscopic mucosal resection with circumferential mucosal incision assisted by submucosal injection of sodium hyaluronate

Hironori Yamamoto; Hiroshi Kawata; Keijiro Sunada; Kiichi Satoh; Yoshinari Kaneko; Kenichi Ido; Kentaro Sugano

BACKGROUND Circumferential mucosal incision around a lesion is effective for reliable endoscopic mucosal resection. However, mucosal incision with a needle knife is difficult, even with submucosal injection of normal saline solution. To make needle-knife incision easier and safer, sodium hyaluronate has been used rather than normal saline solution. The aim of this study was to evaluate the clinical outcome of endoscopic mucosal resection with circumferential mucosal incision assisted by submucosal injection of sodium hyaluronate. METHODS For 70 gastric lesions treated by submucosal injection of sodium hyaluronate, the size of the lesion and the resection specimen, the en bloc resection rate, complications, and local recurrence during follow-up were assessed. RESULTS The mean size of the lesions and resection specimens were, respectively, 19.9 mm and 30.0 mm. The en bloc resection rates were 89% (42/47) for lesions up to 20 mm in diameter and 48% (11/23) for those greater than 20 mm (1-20 mm vs. >20 mm, p = 0.0004). Three patients underwent surgery because of invasive cancer in the EMR specimen. During follow-up (median 14 months, range 3-38 months), 2 recurrent lesions were found. No major complication occurred. CONCLUSIONS Submucosal injection of sodium hyaluronate is a reliable method with a high success rate for en bloc resection of lesions up to 20 mm in diameter. Mucosal incision with a needle knife can be performed safely with submucosal injection of sodium hyaluronate.


Digestive Endoscopy | 2009

ENDOSCOPIC SUBMUCOSAL DISSECTION FOR SUPERFICIAL DUODENAL NEOPLASMS

Tetsuro Honda; Hironori Yamamoto; Hiroyuki Osawa; Mitsuyo Yoshizawa; Hidetoshi Nakano; Keijiro Sunada; Kazunobu Hanatsuka; Kentaro Sugano

Endoscopic submucosal dissection (ESD) has emerged as a novel technique for achieving en bloc resection for superficial neoplasms limited to the mucosa. ESD was originally developed in Japan as a method of endoscopic resection of superficial gastric cancers. In our hospital, ESD has been used concurrently in other parts of the gastrointestinal tract, including the esophagus and colorectum from the beginning of its development. However, ESD in the duodenum is considered more challenging than other parts. From August 2005 to March 2008, a total of 15 superficial duodenal neoplastic lesions in 14 patients were treated with endoscopic resection. Of these, nine underwent ESD. We report our experience with duodenal ESD with a combination of ST hood and hook knife.


Clinical Gastroenterology and Hepatology | 2010

Long-term Outcome of Patients With Obscure Gastrointestinal Bleeding Investigated by Double-Balloon Endoscopy

Satoshi Shinozaki; Hironori Yamamoto; Tomonori Yano; Keijiro Sunada; Tomohiko Miyata; Yoshikazu Hayashi; Masayuki Arashiro; Kentaro Sugano

BACKGROUND & AIMS It is often difficult to determine the cause of obscure gastrointestinal bleeding (OGIB). We evaluated the diagnostic yield and long-term outcome of patients with OGIB by using double-balloon endoscopy (DBE). METHODS In this large, retrospective cohort study, DBE was performed in 200 consecutive patients with OGIB. Follow-up data were available from 151 patients for 29.7 months (range, 6-78 months), and clinical outcome was assessed. RESULTS DBE detected bleeding sources in 155 of 200 patients (77.5%). The most frequent source detected was small intestine ulcers/erosions (64 patients). Patients who underwent DBE within 1 month after the last episode of overt bleeding had a better yield of positive findings than those who did not (84%, 107/128 patients vs 57%, 24/42; P = .002). The overall rate of control of OGIB was 64% (97/151 patients). Patients with vascular lesions of the small intestine had a significantly lower rate of control of OGIB than those with other small intestine lesions (40%, 12/30 patients vs 74%, 52/70; P = .001). A requirement for a large transfusion before DBE (P = .012), multiple lesions (P = .010), and suspicious (not definite) lesions (P = .038) each significantly increased the likelihood of overt rebleeding in patients with vascular lesions of the small intestine. CONCLUSIONS DBE is useful for the diagnosis of patients with OGIB and should be performed as soon as possible after overt OGIB. Patients with vascular lesions of the small intestine should be followed with particular care.


Gastrointestinal Endoscopy | 2009

A comparison of conventional endoscopy, chromoendoscopy, and the optimal-band imaging system for the differentiation of neoplastic and non-neoplastic colonic polyps

Kazutomo Togashi; Hiroyuki Osawa; Koji Koinuma; Yoshikazu Hayashi; Tomohiko Miyata; Keijiro Sunada; Mitsuhiro Nokubi; Hisanaga Horie; Hironori Yamamoto

BACKGROUND The diagnostic accuracy of conventional endoscopy for small colonic polyps is not satisfactory. Optimal band imaging (OBI) enhances the contrast of the mucosal surface without the use of dye. OBJECTIVE To evaluate the diagnostic accuracy for the differentiation of neoplastic and non-neoplastic colorectal polyps by using magnified OBI colonoscopy. DESIGN An open prospective study. SETTING Jichi Medical University, Japan. PATIENTS A total of 133 colonoscopy cases. MAIN OUTCOME MEASUREMENT A comparative study of the overall accuracy, sensitivity, and specificity for the differentiation of neoplastic and non-neoplastic colorectal polyps < or =5 mm in size by capillary-pattern diagnosis by using conventional colonoscopy, capillary-pattern diagnosis in OBI, and pit-pattern diagnosis in chromoendoscopy with low magnification. RESULTS A total of 107 polyps, composed of 80 neoplastic and 27 non-neoplastic polyps, were evaluated. OBI clearly showed the capillary network of the surface mucosa of neoplastic polyps at low magnification, whereas the surface mucosa of non-neoplastic polyps showed up as a pale lesion. The capillary pattern in conventional colonoscopy had 74% accuracy, 71% sensitivity, and 81% specificity for neoplastic polyps. The accuracy and sensitivity were significantly lower than those that used the capillary pattern in OBI (accuracy 87% and sensitivity 93%) and the pit pattern in chromoendoscopy (accuracy 86% and sensitivity 90%). There were no significant differences in specificity (OBI 70% and chromoendoscopy 74%). The kappa analysis indicated good agreement in both OBI and chromoendoscopy. CONCLUSIONS Capillary-pattern diagnosis in OBI is superior to that in conventional endoscopy and is not significantly different from pit-pattern diagnosis for predicting the histology of small colorectal polyps.


Journal of Gastroenterology | 2009

Double-balloon endoscopy : past, present, and future

Keijiro Sunada; Hironori Yamamoto

Double-balloon endoscopy (DBE) was developed as a new technique for visualization of and intervention in the entire small intestine. In DBE, the intestinal walls are held apart by a balloon attached to the distal end of a soft overtube. DBE has been reported worldwide to be very useful for not only diagnosis but also endoscopic therapy. Biopsy samples of small intestinal tumors can be obtained using DBE, and the appropriate treatment can be selected before a surgical procedure. For inflammatory diseases, DBE can reveal the localization of ulcers in the lumen (on the mesenteric or antimesenteric side), which is important for differential diagnosis. Some endoscopic therapies such as hemostatic procedures, polypectomy, and dilation therapy for benign strictures can be performed in the same manner as in the large intestine. DBE may also be suitable for colonoscopy for difficult insertion cases and therapeutic procedures such as endoscopic submucosal dissection. Furthermore, a double-balloon endoscope can be selectively inserted into the afferent loop to perform endoscopic retrograde cholangiopancreatography in patients with Roux-en-Y anastomosis, allowing various kinds of endoscopic treatments for biliary diseases to be successfully performed. Endoscopic therapy in the small intestine, whose wall is very thin, should be performed with special care to avoid complications such as bleeding and perforation. In the future, improvement is expected in terms of maneuverability, therapeutic capability, and imaging technology such as the addition of a magnifying function and flexible spectral imaging color enhancement. We anticipate that DBE will contribute to the establishment of medical science of the small intestine and to research elucidating the mechanisms of small intestinal diseases.


Gastrointestinal Endoscopy | 2010

Safety and efficacy of double-balloon enteroscopy in pediatric patients

Naoyuki Nishimura; Hironori Yamamoto; Tomonori Yano; Yoshikazu Hayashi; Masayuki Arashiro; Tomohiko Miyata; Keijiro Sunada; Kentaro Sugano

BACKGROUND Although double-balloon enteroscopy (DBE) is performed increasingly often in adults, few findings are available on the use of DBE in pediatric patients in the published literature. OBJECTIVES The aim of our study was to evaluate the safety and efficacy of DBE in pediatric patients. DESIGN A retrospective database review. SETTING AND PATIENTS A database analysis was performed on all pediatric patients (18 years old or younger) who underwent DBE at the Jichi Medical University Hospital between September 2000 and October 2008 selected from a total of 825 patients. MAIN OUTCOME MEASUREMENTS Clinical utility and safety of DBE in pediatric patients. RESULTS A total of 92 procedures were performed in 48 patients (27 male, 21 female) with a median age (range) of 12.2 (4-18) years. DBE was performed with the patients under general anesthesia in 43 procedures and under moderate sedation in 49 procedures. The most common indication for DBE was treatment of a stricture of a biliary anastomosis after living-donor liver transplantation with establishment of Roux-en-Y hepaticojejunostomy (23 patients). Endoscopic retrograde cholangiography using DBE was performed, and endoscopic therapy could be performed successfully in 13 (56%) patients. The second most common indication was obscure GI bleeding (10 patients); the lesions responsible for the bleeding were found in 7 (70%) patients. Other indications included surveillance and treatment of hereditary polyposis syndromes (5 patients), abdominal pain (4 patients), and inflammatory bowel disease (2 patients). The overall diagnostic yield was 65% (31 of the 48 patients). Postpolypectomy bleeding occurred in 1 case, but no other complications such as perforation and pancreatitis were observed. LIMITATIONS Small number of patients, participation bias, and single centers experience. CONCLUSIONS DBE is a safe and clinically useful endoscopic procedure in pediatric patients.


Inflammopharmacology | 2007

Double balloon endoscopy in two hundred fifty cases for the diagnosis and treatment of small intestinal disorders.

H. Kita; Hironori Yamamoto; Tomonori Yano; Tomohiko Miyata; Michiko Iwamoto; Keijiro Sunada; Masayuki Arashiro; Yoshikazu Hayashi; Kenichi Ido; Kentaro Sugano

Abstract.Double balloon endoscopy is based on a new insertion mode in which two balloons at the distal ends of both an endoscope and an overtube are operated in combination. We have performed 419 enteroscopic examinations in 250 patients using the Fujinon double balloon endoscopy system between September 2000 and October 2005. Total enteroscopy was successfully achieved by the combination of both oral and anal approaches in 55 out of 71 cases in whom total enteroscopy was intended. Of 250 patients, ulcerative and/or erosive lesions were found in 49 cases and tumors/polyps were found in 49 cases. We also found 26 cases of vascular lesion, including angiodysplasia. Endoscopic treatments, including hemostasis using either clipping devices or electro coagulation, polypectomy, endoscopic mucosal resection, balloon dilation, and stent placement was successfully carried out. Double balloon enteroscopy is both feasible and useful technique for the diagnosis as well as treatment of small intestinal disorders.


Gastrointestinal Endoscopy | 2011

Nonsurgical management of small-bowel polyps in Peutz–Jeghers syndrome with extensive polypectomy by using double-balloon endoscopy

Hirotsugu Sakamoto; Hironori Yamamoto; Yoshikazu Hayashi; Tomonori Yano; Tomohiko Miyata; Naoyuki Nishimura; Hakuei Shinhata; Hiroyuki Sato; Keijiro Sunada; Kentaro Sugano

BACKGROUND The major problem in the management of Peutz-Jeghers syndrome (PJS) is small-bowel polyps, which can cause intussusception and bleeding. Double-balloon endoscopy (DBE) enables endoscopic resection of small-bowel polyps. OBJECTIVE The aim of this study was to determine the efficacy and safety of endoscopic management of small-bowel polyps in PJS patients by using DBE. DESIGN Retrospective chart review. SETTING Single university hospital. PATIENTS Consecutive patients with PJS who underwent multiple sessions of DBE for evaluation or treatment of small-bowel polyps between September 2000 and April 2009. INTERVENTIONS Endoscopic resection of small-bowel polyps in PJS patients was performed by using DBE. MAIN OUTCOME MEASUREMENTS Efficacy, safety, and long-term laparotomy rate after the procedures were evaluated. RESULTS Fifteen patients (10 men, mean age 34.0 ± 15.8 years) underwent DBE for a mean 3.0 ± 1.0 sessions. The mean numbers of resected polyps larger than 20 mm significantly decreased as sessions advanced (first, 3.6; second, 1.3; third, 0.7; fourth, 0.4; and fifth, 1.0; P = .02). The mean maximum sizes of resected polyps also significantly decreased at each session: 33, 19, 12, 17, and 30 mm (P = .01). One patient had a perforation, but was managed conservatively. Other complications were pancreatitis (n = 2) and bleeding (n = 2). Only 1 patient underwent surgery for intussusception during the study period. LIMITATIONS This was a small single-center retrospective study of short duration. CONCLUSIONS Endoscopic management of small-bowel polyps in PJS patients by using DBE is safe and effective and avoids urgent laparotomy.


Journal of Gastroenterology | 2009

Diagnosis of endoscopic Barrett's esophagus by transnasal flexible spectral imaging color enhancement

Hiroyuki Osawa; Hironori Yamamoto; Naoshi Yamada; Mitsuyo Yoshizawa; Keijiro Sunada; Hiroto Kita; Hironari Ajibe; Kiichi Satoh; Kentaro Sugano

BackgroundThe diagnosis of endoscopic Barrett’s esophagus (BE) has been under discussion for the past decade because palisade vessels may be obscured by inflammation or the location of upper end of gastric fold may be diversely changed. The flexible spectral imaging color enhancement (FICE) system can reconstruct improved spectral images decomposed from ordinary endoscopic images with free selection of three wavelengths, and can provide non-magnified images with high light intensity.MethodsTo evaluate whether the transnasal FICE system enables easier diagnosis of endoscopic BE, 72 patients with endoscopic BE were observed prospectively with a transnasal endoscope using both conventional images and FICE images. The visualization of palisade vessels and the identification of the demarcation between endoscopic BE mucosa and gastric mucosa were compared between FICE images and conventional endoscopic images, and the CIELAB color differences were calculated among palisade vessels, background BE mucosa and gastric folds.ResultsPalisade vessels could be more clearly visualized in BE mucosa with transnasal FICE than with conventional endoscopy. Demarcation between whitish BE mucosa and the upper end of the brownish gastric mucosa could be clearly identified using transnasal FICE images. Greater color differences existed with FICE images between palisade vessels and background BE mucosa as well as between BE mucosa and gastric folds than with conventional images, leading to better contrasting images.ConclusionsThe transnasal FICE system enables clear visualization of palisade vessels and provides better contrasting images of the demarcation between the BE mucosa and the gastric mucosa, and thus contributes to easier diagnosis of endoscopic BE.

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Tomonori Yano

Jichi Medical University

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Kentaro Sugano

Jichi Medical University

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Hiroyuki Sato

Jichi Medical University

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Kenichi Ido

Jichi Medical University

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