Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Keisuke Iwata is active.

Publication


Featured researches published by Keisuke Iwata.


Clinical Gastroenterology and Hepatology | 2012

Use of Samples From Endoscopic Ultrasound–Guided 19-Gauge Fine-Needle Aspiration in Diagnosis of Autoimmune Pancreatitis

Takuji Iwashita; Ichiro Yasuda; Shinpei Doi; Nobuhiro Ando; Masanori Nakashima; Seiji Adachi; Yoshinobu Hirose; Tsuyoshi Mukai; Keisuke Iwata; Eiichi Tomita; Takao Itoi; Hisataka Moriwaki

BACKGROUND & AIMS Histologic techniques are used to distinguish autoimmune pancreatitis (AIP) from pancreatic malignancies and to confirm the etiology of pancreatitis. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a well-established technique used in the diagnosis of pancreatic cancer. However, it is unclear whether specimens obtained from pancreatic lesions by EUS-FNA are adequate for the histologic diagnosis of AIP, because the evaluation of tissue architecture and immunostaining assays usually require larger samples. METHODS We evaluated samples collected by EUS-FNA with a conventional 19-gauge needle by histologic analysis, looking for features of AIP. We analyzed data from 44 patients who were diagnosed with AIP and underwent EUS-FNA with a 19-gauge needle from January 2004 to September 2010. The FNA specimens were reviewed by histologic analysis; AIP was diagnosed based on the presence of lymphoplasmacytic sclerosing pancreatitis or immunoglobulin (Ig)G4-positive plasma cells in the infiltrate. RESULTS The specimen amount was inadequate from 3 patients. Among the remaining 41 patients, histopathologic analysis revealed lymphoplasmacytic sclerosing pancreatitis in 17 samples and IgG4-positive plasma cells in 5 (3 samples were positive for both); no samples had granulocytic epithelial lesions. Therefore, 19 patients (43%) were diagnosed with AIP based on histologic analysis. One patient had temporary abdominal pain. CONCLUSIONS EUS-FNA, with a 19-gauge needle, is a safe and reliable procedure for obtaining pancreatic samples for the histologic analysis of AIP. Although it does not have a high diagnostic yield, it might be useful in patients without typical features of AIP because it would allow patients to avoid surgery.


Digestive Endoscopy | 2011

PREDICTIVE FACTORS FOR PAIN RELIEF AFTER ENDOSCOPIC ULTRASOUND-GUIDED CELIAC PLEXUS NEUROLYSIS

Keisuke Iwata; Ichiro Yasuda; Masamichi Enya; Tsuyoshi Mukai; Masanori Nakashima; Shinpei Doi; Takuji Iwashita; Eiichi Tomita; Hisataka Moriwaki

Background:  Celiac plexus neurolysis (CPN) is an established treatment for upper abdominal cancer pain. Recently, endoscopic ultrasound‐guided CPN (EUS‐CPN) was introduced and has enabled the performance of CPN under real‐time imaging guidance, thereby making this technique much safer and easier. However, this procedure is not always efficacious, and a limited number of patients benefit from it. It should not be recommended for patients suspected of having unfavorable outcomes. We determined the predictive factors for response to EUS‐CPN in order to enable rational selection of the therapeutic strategy.


Digestive Endoscopy | 2009

EUS‐GUIDED PANCREATIC PSEUDOCYST DRAINAGE

Ichiro Yasuda; Keisuke Iwata; Tsuyoshi Mukai; Takuji Iwashita; Hisataka Moriwaki

Background:  Endoscopic ultrasound‐guided pancreatic pseudocyst drainage (EUS‐PPD) has recently become popular. However, this technique has not yet been standardized, and the available instruments have not been sufficiently developed. Therefore, it is difficult to determine the treatment strategy and the choice of devices.


Gastrointestinal Endoscopy | 2016

EUS-guided rendezvous for difficult biliary cannulation using a standardized algorithm: a multicenter prospective pilot study (with videos)

Takuji Iwashita; Ichiro Yasuda; Tsuyoshi Mukai; Keisuke Iwata; Nobuhiro Ando; Shinpei Doi; Masanori Nakashima; Shinya Uemura; Masatoshi Mabuchi; Masahito Shimizu

BACKGROUND AND AIMS Biliary cannulation is necessary in therapeutic ERCP for biliary disorders. EUS-guided rendezvous (EUS-RV) can salvage failed cannulation. Our aim was to determine the safety and efficacy of EUS-RV by using a standardized algorithm with regard to the endoscope position in a prospective study. METHODS EUS-RV was attempted after failed cannulation in 20 patients. In a standardized approach, extrahepatic bile duct (EHBD) cannulation was preferentially attempted from the second portion of the duodenum (D2) followed by additional approaches to the EHBD from the duodenal bulb (D1) or to the intrahepatic bile duct from the stomach, if necessary. A guidewire was placed in an antegrade fashion into the duodenum. After the guidewire was placed, the endoscope was exchanged for a duodenoscope to complete the cannulation. RESULTS The bile duct was accessed from the D2 in 10 patients, but from the D1 in 5 patients and the stomach in 4 patients because of no dilation or tumor invasion at the distal EHBD. In the remaining patient, biliary puncture was not attempted due to the presence of collateral vessels. The guidewire was successfully manipulated in 80% of patients: 100% (10/10) with the D2 approach and 66.7% (6/9) with other approaches. The overall success rate was 80% (16/20). Failed EUS-RV was salvaged with a percutaneous approach in 2 patients, repeat ERCP in 1 patient, and conservative management in 1 patient. Minor adverse events occurred in 15% of patients (3/20). CONCLUSIONS EUS-RV is a safe and effective salvage method. Using EUS-RV to approach the EHBD from the D2 may improve success rates.


Endoscopy | 2011

Carbon dioxide insufflation vs. conventional saline irrigation for peroral video cholangioscopy.

Shinpei Doi; Ichiro Yasuda; Masanori Nakashima; Takuji Iwashita; Katsuhisa Toda; Tsuyoshi Mukai; Keisuke Iwata; Takao Itoi; Hisataka Moriwaki

BACKGROUND AND STUDY AIMS Recent studies have evaluated the efficacy of peroral cholangioscopy (POCS) for diagnosis of biliary diseases. In order to obtain clear images with POCS, saline irrigation, which is performed to replace yellow bile, is carried out for an extended duration. The aim of this study was to evaluate the feasibility of replacing saline irrigation with CO₂ insufflation during POCS. PATIENTS AND METHODS A total of 36 patients who had bile duct lesions and were due to undergo POCS were enrolled in the study. Of these patients, 18 underwent POCS using saline irrigation followed by CO₂ insufflation, and 18 patients underwent the reverse approach. The two methods were compared with regard to the time required to obtain a clear endoscopic image and the quality of the images. RESULTS The median time required to obtain a clear endoscopic image using CO₂ insufflation (5.0 min) was significantly shorter than that required for saline irrigation (22.5 min; P < 0.001). The quality of the endoscopic images obtained was similar in 27 cases. However, CO₂ insufflation provided better images in four cases that showed an abundance of mucin or biliary sludge, and saline irrigation was superior to CO₂ insufflation in five cases that showed severe stricture with bleeding and tall papillary lesions. CONCLUSIONS CO₂ insufflation during POCS can reduce procedure time and simplify cholangioscopy. The overall image quality was similar to that obtained with conventional saline irrigation.


Journal of Hepato-biliary-pancreatic Sciences | 2011

Comparison of axial force and cell width of self-expandable metallic stents: which type of stent is better suited for hilar biliary strictures?

Tsuyoshi Mukai; Ichiro Yasuda; Hiroyuki Isayama; Masanori Nakashima; Shinpei Doi; Takuji Iwashita; Keisuke Iwata; Tomohiro Kato; Eiichi Tomita; Hisataka Moriwaki

BackgroundVarious types of self-expandable metallic stents (SEMSs) are commercially available. However, few reports have compared the performance of the various SEMSs. In addition to long-term patency, maneuverability during initial placement and feasibility of re-intervention for the stent occlusion are also very important.MethodsIn this retrospective analysis, we compared the duration of stent patency and frequency of re-interventions in 96 patients diagnosed with unresectable hilar biliary strictures in whom initial 10-mm SEMSs were inserted between June 1999 and November 2008.ResultsBased on Kaplan–Meier curves, significantly shorter patency duration was noted for SEMSs with moderate axial force (AF) than for other groups of SEMSs with low AF. Endoscopic re-interventions for SEMS occlusion were easier in a group of SEMSs with low AF and large cell width than in other groups of SEMSs.ConclusionsWith respect to patency duration and the frequency of re-intervention required, we consider that SEMSs with low AF and large cell width are favorable for hilar biliary strictures.


Digestive Endoscopy | 2017

Endoscopic ultrasound-guided antegrade biliary stenting for unresectable malignant biliary obstruction in patients with surgically altered anatomy: Single-center prospective pilot study

Takuji Iwashita; Ichiro Yasuda; Tsuyoshi Mukai; Keisuke Iwata; Shinpei Doi; Shinya Uemura; Masatoshi Mabuchi; Mitsuru Okuno; Masahito Shimizu

Endoscopic retrograde cholangiography (ERCP) with biliary stenting for the treatment of unresectable malignant biliary obstruction (MBO) is challenging among patients with surgically altered anatomy. Endoscopic ultrasound‐guided antegrade biliary stenting (EUS‐ABS) was introduced as an alternative biliary drainage method, although it has not yet been well studied. In this single‐center prospective pilot study, we aimed to evaluate the feasibility and safety of EUS‐ABS for MBO in patients with surgically altered anatomy.


Oncotarget | 2017

A multicenter prospective phase II study of first-line modified FOLFIRINOX for unresectable advanced pancreatic cancer

Kensaku Yoshida; Takuji Iwashita; Shinya Uemura; Akinori Maruta; Mitsuru Okuno; Nobuhiro Ando; Keisuke Iwata; Jyunji Kawaguchi; Tsuyoshi Mukai; Masahito Shimizu

Background FOLFIRINOX (FX) has been reported as an effective treatment for unresectable advanced pancreatic cancer. However, FX is associated with a high incidence of adverse events (AEs). A previous phase II study in Japan showed high incidences of hematological AEs, including febrile neutropenia (22.2%). A modified FX regimen (mFX) may decrease the rates of AEs and be more effective than FX by improving the treatment compliance. Aims To assess the safety and efficacy of first-line mFX for unresectable advanced pancreatic cancer. Patients and methods This was as a multicenter prospective phase II study in chemotherapy-naïve Japanese patients with pathologically confirmed unresectable advanced pancreatic adenocarcinoma or adenosquamous carcinoma. Treatment with mFX (85 mg/m2 oxaliplatin, 150 mg/m2 irinotecan, and 200 mg/m2 l-leucovorin, followed by 46-h continuous infusion of 2400 mg/m2 5-fluorouracil) was administered every 2 weeks. The primary endpoint was the response rate. The secondary endpoints were overall survival, progression-free survival, and safety. Results Thirty-one patients (18 men; median age, 64 years) were enrolled. A median of 13 treatment cycles were administered during a median follow-up period of 14.2 months. The response rate, median overall survival, and median progression-free survival were 38.7%, 14.9 months, and 7.0 months, respectively. Grade 3 or 4 AEs included neutropenia (83.9%), febrile neutropenia (16.1%), peripheral sensory neuropathy (9.7%), thrombocytopenia (6.5%), diarrhea (6.5%), anorexia (6.5%), and vomiting (3.2%). Conclusion Compared to FX, mFX may result in fewer Grade 3 or 4 non-hematological AEs, with a comparable response rate. However, further efforts might be required to reduce hematological AEs.


Pancreatology | 2018

Endoscopic duodenal stent versus surgical gastrojejunostomy for gastric outlet obstruction in patients with advanced pancreatic cancer

Shinya Uemura; Takuji Iwashita; Keisuke Iwata; Tsuyoshi Mukai; Shinji Osada; Takafumi Sekino; Takahito Adachi; Masahiko Kawai; Ichiro Yasuda; Masahito Shimizu

BACKGROUND Malignant gastric outlet obstruction (GOO) often develops in patients with advanced pancreatic cancer (APC). It is not clear whether endoscopic duodenal stenting (DS) or surgical gastrojejunostomy (GJJ) is preferable as palliative treatment. AIMS To compare the efficacy and safety of GJJ and DS for GOO with APC. METHODS Consecutive 99 patients who underwent DS or GJJ for GOO with APC were evaluated. We compared the technical and clinical success rates, the incidence of adverse event (AE), the time to start chemotherapy and discharge and survival durations between DS and GJJ. Prognostic factors for overall survival (OS) were investigated on the multivariate analysis. RESULTS GOO was managed with GJJ in 35 and DS in 64. The technical and clinical success rates were comparable. DS was associated with shorter time to start oral intake and earlier chemotherapy start and discharge. No difference was seen in the early and late AE rates. Multivariate analyses of prognostic factors for OS showed that performance status ≧2, administration of chemotherapy, and presence of obstructive jaundice to be significant factors. There were no significant differences in survival durations between the groups, regardless of the PS. CONCLUSIONS There were no significant differences in the technical and clinical success and AE rates and survival duration between DS and GJJ in management of GOO by APC. DS may be a preferable option over GJJ given that it will lead to an earlier return to oral intake, a shortened length of hospital stay, and finally an earlier referral for chemotherapy.


Digestive Endoscopy | 2018

Hybrid procedure combining endoscopic gallbladder lavage and internal drainage with elective cholecystectomy for acute cholecystitis: A prospective pilot study (The BLADE study)

Shinpei Doi; Ichiro Yasuda; Masatoshi Mabuchi; Keisuke Iwata; Nobuhiro Ando; Takuji Iwashita; Shinya Uemura; Mitsuru Okuno; Tsuyoshi Mukai; Seiji Adachi; Keizo Taniguchi

Percutaneous transhepatic drainage is the most common method for non‐operative gallbladder drainage, but the technique does have several disadvantages because of its invasive nature and requirement for continuous drainage. To overcome these disadvantages, we developed a novel procedure, endoscopic gallbladder lavage followed by stent placement, carried out in a single endoscopic session. Our aim was to prospectively evaluate the efficacy and safety of this procedure in patients with acute cholecystitis.

Collaboration


Dive into the Keisuke Iwata's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge