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Dive into the research topics where Kosuke Okuwaki is active.

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Featured researches published by Kosuke Okuwaki.


World Journal of Gastroenterology | 2013

Short-type single balloon enteroscope for endoscopic retrograde cholangiopancreatography with altered gastrointestinal anatomy

Hiroshi Yamauchi; Mitsuhiro Kida; Kosuke Okuwaki; Shiro Miyazawa; Tomohisa Iwai; Miyoko Takezawa; Hidehiko Kikuchi; Maya Watanabe; Hiroshi Imaizumi; Wasaburo Koizumi

AIM To evaluate the effectiveness of a short-type single-balloon-enteroscope (SBE) for endoscopic retrograde cholangiopancreatography (ERCP) in patients with a reconstructed intestine. METHODS Short-type SBE was developed to perform ERCP in postoperative patients with a reconstructed intestine. Short-type SBE is a direct-viewing endoscope with the following specifications: working length, 1520 mm; total length, 1840 mm; channel diameter, 3.2 mm. In addition, short-type SBE has a water-jet channel. The study group comprised 22 patients who underwent 31 sessions of short-type SBE-assisted ERCP from June 2011 through May 2012. Reconstruction was performed by Billroth-II (B-II) gastrectomy in 6 patients (8 sessions), Roux-en-Y (R-Y) gastrectomy in 14 patients (21 sessions), and R-Y hepaticojejunostomy in 2 patients (2 sessions). We retrospectively studied the rate of reaching the blind end (papilla of Vater or choledochojejunal anastomosis), mean time required to reach the blind end, diagnostic success rate (defined as the rate of successfully imaging the bile and pancreatic ducts), therapeutic success rate (defined as the rate of successfully completing endoscopic treatment), mean procedure time, and complications. RESULTS Among the 31 sessions of ERCP, the rate of reaching the blind end was 88% in B-II gastrectomy, 91% in R-Y gastrectomy, and 100% in R-Y hepaticojejunostomy. The mean time required to reach the papilla was 18.3 min in B-II gastrectomy, 21.1 min in R-Y gastrectomy, and 32.5 min in R-Y hepaticojejunostomy. The diagnostic success rates in all patients and those with an intact papilla were respectively 86% and 86% in B-II gastrectomy, 90% and 87% in R-Y gastrectomy, and 100% in R-Y hepaticojejunostomy. The therapeutic success rates in all patients and those with an intact papilla were respectively 100% and 100% in B-II gastrectomy, 94% and 92% in R-Y gastrectomy, and 100% in R-Y hepaticojejunostomy. Because the channel diameter was 3.2 mm, stone extraction could be performed with a wire-guided basket in 12 sessions, and wire-guided intraductal ultrasonography could be performed in 8 sessions. As for complications, hyperamylasemia (defined as a rise in serum amylase levels to more than 3 times the upper limit of normal) occurred in 1 patient (7 sessions) with a B-II gastrectomy and 4 patients (19 sessions) with an R-Y gastrectomy. After ERCP in patients with an R-Y gastrectomy, 2 patients (19 sessions) had pancreatitis, 1 patient (21 sessions) had gastrointestinal perforation, and 1 patient (19 sessions) had papillary bleeding. Pancreatitis and bleeding were both mild. Gastrointestinal perforation improved after conservative treatment. CONCLUSION Short-type SBE is effective for ERCP in patients with a reconstructed intestine and allows most conventional ERCP devices to be used.


Cancer | 2013

Clinicopathologic characteristics of pancreatic neuroendocrine tumors and relation of somatostatin receptor type 2A to outcomes

Kosuke Okuwaki; Mitsuhiro Kida; Tetuo Mikami; Hiroshi Yamauchi; Hiroshi Imaizumi; Shiro Miyazawa; Tomohisa Iwai; Miyoko Takezawa; Makoto Saegusa; Masahiko Watanabe; Wasaburo Koizumi

The impact of somatostatin receptor type 2 (SSTR‐2a) expression levels on outcomes in patients with pancreatic neuroendocrine tumors (PNETs) has not been evaluated.


World Journal of Gastroenterology | 2015

Innovations and techniques for balloon-enteroscope-assisted endoscopic retrograde cholangiopancreatography in patients with altered gastrointestinal anatomy

Hiroshi Yamauchi; Mitsuhiro Kida; Hiroshi Imaizumi; Kosuke Okuwaki; Shiro Miyazawa; Tomohisa Iwai; Wasaburo Koizumi

Endoscopic retrograde cholangiopancreatography (ERCP) remains challenging in patients who have undergone surgical reconstruction of the intestine. Recently, many studies have reported that balloon-enteroscope-assisted ERCP (BEA-ERCP) is a safe and effective procedure. However, further improvements in outcomes and the development of simplified procedures are required. Percutaneous treatment, Laparoscopy-assisted ERCP, endoscopic ultrasound-guided anterograde intervention, and open surgery are effective treatments. However, treatment should be noninvasive, effective, and safe. We believe that these procedures should be performed only in difficult-to-treat patients because of many potential complications. BEA-ERCP still requires high expertise-level techniques and is far from a routinely performed procedure. Various techniques have been proposed to facilitate scope insertion (insertion with percutaneous transhepatic biliary drainage (PTBD) rendezvous technique, Short type single-balloon enteroscopes with passive bending section, Intraluminal injection of indigo carmine, CO2 inflation guidance), cannulation (PTBD or percutaneous transgallbladder drainage rendezvous technique, Dilation using screw drill, Rendezvous technique combining DBE with a cholangioscope, endoscopic ultrasound-guided rendezvous technique), and treatment (overtube-assisted technique, Short type balloon enteroscopes) during BEA-ERCP. The use of these techniques may allow treatment to be performed by BEA-ERCP in many patients. A standard procedure for ERCP yet to be established for patients with a reconstructed intestine. At present, BEA-ERCP is considered the safest and most effective procedure and is therefore likely to be recommended as first-line treatment. In this article, we discuss the current status of BEA-ERCP in patients with surgically altered gastrointestinal anatomy.


World Journal of Gastroenterology | 2015

Passive-bending, short-type single-balloon enteroscope for endoscopic retrograde cholangiopancreatography in Roux-en-Y anastomosis patients.

Hiroshi Yamauchi; Mitsuhiro Kida; Kosuke Okuwaki; Shiro Miyazawa; Tomohisa Iwai; Shuko Tokunaga; Miyoko Takezawa; Hiroshi Imaizumi; Wasaburo Koizumi

AIM To evaluate short-type-single-balloon enteroscope (SBE) with passive-bending, high-force transmission functions for endoscopic retrograde cholangiopancreatography (ERCP) in patients with Roux-en-Y anastomosis. METHODS Short-type SBE with this technology (SIF-Y0004-V01; working length, 1520 mm; channel diameter, 3.2 mm) was used to perform 50 ERCP procedures in 37 patients with Roux-en-Y anastomosis. The rate of reaching the blind end, time required to reach the blind end, diagnostic and therapeutic success rates, and procedure time and complications were studied retrospectively and compared with the results of 34 sessions of ERCP performed using a short-type SBE without this technology (SIF-Y0004; working length, 1520 mm; channel diameter, 3.2 mm) in 25 patients. RESULTS The rate of reaching the blind end was 90% with SIF-Y0004-V01 and 91% with SIF-Y0004 (P = 0.59). The median time required to reach the papilla was significantly shorter with SIF-Y0004-V01 than with SIF-Y0004 (16 min vs 24 min, P = 0.04). The diagnostic success rate was 93% with SIF-Y0004-V01 and 84% with SIF-Y0004 (P = 0.17). The therapeutic success rate was 95% with SIF-Y0004-V01 and 96% with SIF-Y0004 (P = 0.68). The median procedure time was 40 min with SIF-Y0004-V01 and 36 min with SIF-Y0004 (P = 0.50). The incidence of hyperamylasemia was 6.0% in the SIF-Y0004-V01 group and 14.7% in the SIF-Y0004 group (P = 0.723). The incidence of pancreatitis was 0% in the SIF-Y0004-V01 group and 5.9% in the SIF-Y0004 group (P > 0.999). The incidence of gastrointestinal perforation was 2.0% (1/50) in the SIF-Y0004-V01 group and 2.9% (1/34) in the SIF-Y0004 group (P > 0.999). CONCLUSION SIF-Y0004-V01 is useful for ERCP in patients with Roux-en-Y anastomosis and may reduce the time required to reach the blind end.


World Journal of Gastroenterology | 2014

First case of IgG4-related sclerosing cholangitis associated with autoimmune hemolytic anemia

Hironori Masutani; Kosuke Okuwaki; Mitsuhiro Kida; Hiroshi Yamauchi; Hiroshi Imaizumi; Shiro Miyazawa; Tomohisa Iwai; Miyoko Takezawa; Wasaburo Koizumi

To our knowledge, patients with immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) associated with autoimmune hemolytic anemia (AIHA) have not been reported previously. Many patients with IgG4-SC have autoimmune pancreatitis (AIP) and respond to steroid treatment. However, isolated cases of IgG4-SC are difficult to diagnose. We describe our experience with a patient who had IgG4-SC without AIP in whom the presence of AIHA led to diagnosis. The patient was a 73-year-old man who was being treated for dementia. Liver dysfunction was diagnosed on blood tests at another hospital. Imaging studies suggested the presence of carcinoma of the hepatic hilus and primary sclerosing cholangitis, but a rapidly progressing anemia developed simultaneously. After the diagnosis of AIHA, steroid treatment was begun, and the biliary stricture improved. IgG4-SC without AIP was thus diagnosed.


World Journal of Gastroenterology | 2016

Clinical implications of doubling time of gastrointestinal submucosal tumors

Shuko Koizumi; Mitsuhiro Kida; Hiroshi Yamauchi; Kosuke Okuwaki; Tomohisa Iwai; Shiro Miyazawa; Miyoko Takezawa; Hiroshi Imaizumi; Wasaburo Koizumi

AIM To evaluate the efficacy of doubling time (DT) of gastrointestinal submucosal tumors (GIST). METHODS From April 1987 through November 2012, a total of 323 patients were given a final histopathological diagnosis of GISTs on surgical resection or endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in Kitasato University East Hospital or Kitasato University Hospital. We studied 53 of these patients (34 with resected tumors and 19 with unresected tumors) whose tumors could be measured on EUS on at least two successive occasions. The histopathological diagnosis was GIST in 34 patients, leiomyoma in 5, schwannoma in 3, ectopic pancreas in 1, hamartoma in 1, cyst in 1, Brunner’s adenoma in 1, and spindle-cell tumor in 7. We retrospectively calculated the DT of GISTs on the basis of the time course of EUS findings to estimate the growth rate of such tumors. RESULTS The DT was 17.2 mo for GIST, as compared with 231.2 mo for leiomyoma, 104.7 mo for schwannoma, 274.9 mo for ectopic pancreas, 61.2 mo for hamartoma, 49.0 mo for cyst, and 134.7 mo for Brunner’s adenoma. The GISTs were divided into risk classes on the basis of tumor diameters and mitotic figures (Fletcher’s classification). The classification was extremely low risk or low risk in 28 patients, intermediate risk in 3, and high risk in 3. DT of GIST according to risk was 24.0 mo for extremely low-risk plus low-risk GIST, 17.1 mo for intermediate-risk GIST, and 3.9 mo for high-risk GIST. DT of GIST was significantly shorter than that of leiomyoma plus schwannoma (P < 0.05), and DT of high-risk GIST was significantly shorter than that of extremely low-risk plus low-risk GIST (P < 0.05). CONCLUSION For GIST, a higher risk grade was associated with a significantly shorter DT. Small SMTs should initially be followed up within 6 mo after detection.


Internal Medicine | 2017

Pancreatic Fistula Extending into the Thigh Caused by the Rupture of an Intraductal Papillary Mucinous Adenoma of the Pancreas

Yuki Shimizu; Hiroshi Imaizumi; Hiroshi Yamauchi; Kosuke Okuwaki; Shiro Miyazawa; Tomohisa Iwai; Miyoko Takezawa; Mitsuhiro Kida; Erina Suzuki; Makoto Saegusa; Wasaburo Koizumi

We herein report the first case of a pancreatic fistula extending into the thigh caused by the rupture of an intraductal papillary mucinous neoplasm (IPMN) of the pancreas. An 80-year-old man was suspected to have necrotizing fasciitis because of right femoral pain. Computed tomography showed fluid retention from the pancreatic head to the right iliopsoas muscle and an IPMN at the pancreatic head. The findings of endoscopic retrograde pancreatography led to the suspicion of a minor leak and a pancreatic stent was placed. The patient died due to an uncontrollable infection. A pathological autopsy showed a pancreatic fistula extending into the thigh that had been caused by the rupture of the IPMN.


Internal Medicine | 2015

A Patient with Pancreatic Castleman's Disease Arising around the Main Pancreatic Duct

Takaaki Matsumoto; Kosuke Okuwaki; Mitsuhiro Kida; Shi-Xu Jiang; Hiroshi Imaizumi; Hiroshi Yamauchi; Shiro Miyazawa; Tomohisa Iwai; Miyoko Takezawa; Hiroshi Tajima; Wasaburo Koizumi

Castlemans disease of the pancreas is extremely rare. To the best of our knowledge, Castlemans disease arising around the main pancreatic duct has not been previously reported. The patient was a 74-year-old man. Abdominal ultrasonography performed at a health check-up revealed a dilated main pancreatic duct. Pancreatic cancer was strongly suspected on various imaging studies. However, the results of a cytological examination of the pancreatic juice were negative for malignancy. The patient did not want to undergo a histological diagnosis by endoscopic ultrasound-guided fine-needle aspiration, thus pylorus-preserving pancreatoduodenectomy was performed. Pancreatic Castlemans disease arising around the main pancreatic was diagnosed by the histopathological examination.


Diagnostic Cytopathology | 2018

Randomized crossover trial comparing EUS-guided fine-needle aspiration with EUS-guided fine-needle biopsy for gastric subepithelial tumors

Tomohisa Iwai; Mitsuhiro Kida; Hiroshi Imaizumi; Shiro Miyazawa; Kosuke Okuwaki; Hiroshi Yamauchi; Toru Kaneko; Rikiya Hasegawa; Eiji Miyata; Wasaburo Koizumi

The purpose of this study is to compare the diagnostic yield of endoscopic ultrasound (EUS)‐guided fine‐needle aspiration (EUS‐FNA) and EUS‐guided fine‐needle biopsy (EUS‐FNB) for gastric subepithelial tumors (SET).


Digestive Endoscopy | 2017

Endoscopic ultrasonography diagnosis of subepithelial lesions

Mitsuhiro Kida; Yusuke Kawaguchi; Eiji Miyata; Rikiya Hasegawa; Toru Kaneko; Hiroshi Yamauchi; Shuko Koizumi; Kosuke Okuwaki; Shiro Miyazawa; Tomohisa Iwai; Hidehiko Kikuchi; Maya Watanabe; Hiroshi Imaizumi; Wasaburo Koizumi

Using endoscopic ultrasonography (EUS), it is practicable to diagnose subepithelial lesions (SEL) with originating layer, echo level, and internal echo pattern etc. Lipoma, lymphangioma, and cyst have characteristic features; therefore, there is no need for endoscopic ultrasound‐guided fine‐needle aspiration (EUS‐FNA). Ectopic pancreas and glomus tumors, which originate from the third and fourth layers, are frequently seen in the antrum. However, ectopic pancreas located in the fundus or body is large and originates from the third and fourth layers (thickening of fourth layer). Each subepithelial lesion has characteristic findings. However, imaging differentiation of tumors originating from the fourth layer is very difficult, even if contrast echo is used. Therefore, EUS‐FNA should be done in these tumors, but the diagnostic yield for small lesions is not sufficient for clinical demands. Generally, those tumors, including small ones, should be first followed up in 6 months, then yearly follow up in cases of no significant change in size and features. When those tumors become larger than 1–2 cm, EUS‐FNA is recommended. Furthermore, unusual SEL and SEL with malignant findings such as nodular, heterogeneous, anechoic area, and ulceration indicate EUS‐FNA. Cap‐attached forward‐viewing echoendoscope is very helpful for EUS‐FNA of small SEL.

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