Keiichi Ikeda

Showa University, Shinagawa, Tōkyō, Japan

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Publications (62)242.93 Total impact

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    ABSTRACT: Abstract Introduction:Successful access to the papilla and cannulation of the desired duct can be technically challenging. A novel second-generation multi-bending backward-oblique viewing duodenoscope (2nd M-D scope) was developed to overcome this difficulty. The aim of the present study was to evaluate the utility of 2nd M-D scope during biliary ERCP. Material and methods: This was a retrospective review of 53 patients with native papilla who underwent biliary ERCP with the 2nd M-D scope. Results:Biliary cannulation and interventional procedures were successfully completed in all patients. In two of these patients, ERCP was initially attempted with a conventional single bending duodenoscope, but biliary cannulation was unsuccessful; one had Billroth-I gastrectomy, and the other had a Type III choledochal cyst. However, with the 2nd M-D scope, biliary cannulation and interventional procedures were successfully achieved. Finally, in nine patients, upward or downward angulation of the proximal bending portion in addition to the distal bending portion was used during ERCP, and the operator's comments demonstrated that it was helpful for obtaining an appropriate en face view to look up to the papilla and facilitate successful biliary cannulation. Conclusion: The newly developed 2nd M-D scope could safely facilitate biliary cannulation in selected patients during ERCP.
    No preview · Article · Sep 2014 · Minimally Invasive Therapy & Allied Technologies
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    ABSTRACT: Endoscopic retrograde cholangiopancreatography (ERCP) has played a major role in the diagnosis of biliary and pancreatic diseases. The prevalence and mortality rate of post-ERCP pancreatitis (PEP) remains a serious issue that needs to be resolved. Here, we report the first ERCP study that was conducted at a high-volume center of an educational institution in Japan. This study investigated patients with suspected biliary and pancreatic diseases who had undergone ERCP between April 2006 and June 2009. We created a database and analyzed preoperative and postoperative data. Patients who had undergone surgery and those with a history of undergoing duodenal papilla treatment were excluded. Mild (n=62) or moderate (n=3) pancreatitis was present in 65 cases (6.21%; 36 men and 29 women). A univariate analysis identified age under 50 years (P=0.01), pancreatography (P<0.001), and biliary stent placement (P<0.001). A Multivariate analysis was performed for evaluating the risk factors associated with PEP. This analysis identified age of the patients under 50 years [P=0.003; odds ratio (OR), 0.37; 95% confidence interval (CI), 0.19-0.71], endoscopic papillary balloon dilation (P=0.012; OR, 4.69; 95% CI, 1.41-15.54), pancreatography (P<0.001; OR, 5.55; 95% CI, 2.98-10.33), and plastic stent placement (P<0.001; OR, 3.77; 95% CI, 2.17-6.54). Descriptive statistics showed that only pancreatography was associated with PEP. An additional sphincterotomy did not increase the risk of PEP (P=0.306; OR, 2.03; 95% CI, 0.52-7.84), and even adjusted for pancreatography. We changed the size of the stent to 7-Fr. In the future, we plan to repeat the same study with a higher number of cases.
    No preview · Article · Apr 2014 · Surgical laparoscopy, endoscopy & percutaneous techniques
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    ABSTRACT: Advanced complex surgery performed with the natural orifice translumenal endoscopic surgery technique requires use of a multitasking platform. The aim of this study is to evaluate the basic functionality of a prototype multitasking platform "EndoSAMURAI" with the use of a biosimulation model and ex vivo porcine stomach. We compared the performance of basic surgical skill tasks between the EndoSAMURAI and standard laparoscopic instrumentation. Basic surgical tasks include cutting, dissection, and suturing and knot tying. Main outcome measurements were the time to complete each task and leak pressure to evaluate the quality of the suturing and knot tying. Although it took longer to perform all basic surgical tasks with the EndoSAMURAI than with laparoscopic instrumentation, all tasks could be performed precisely and with an accuracy comparable to that of the laparoscopic technique. Leak pressures of the gastric closure site between both techniques were also comparable.
    No preview · Article · Apr 2014 · Surgical laparoscopy, endoscopy & percutaneous techniques
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    ABSTRACT: Upper gastrointestinal endoscopy is mostly performed under sedation and has a low yield of relevant gastric lesions in patients without alarm symptoms. Simpler screening tests such as capsule endoscopy could be helpful, but gastric visualization is insufficient with the current passive capsules. A magnetically guided gastric capsule was prospectively evaluated in patients with routine indications for gastroscopy. A total of 189 symptomatic patients (105 male; mean age 53 y) from 2 French centers subsequently and blindly underwent capsule and conventional gastroscopy by 9 and 6 examiners, respectively. The final gold standard was unblinded conventional gastroscopy with biopsy under propofol sedation. Main outcome was accuracy (sensitivity/specificity) of capsule gastroscopy for diagnosis of major gastric lesions, defined as those lesions requiring conventional gastroscopy for biopsy or removal. Twenty-three major lesions were found in 21 patients. Capsule accuracy was 90.5% [95% confidence interval (CI), 85.4%-94.3%] with a specificity of 94.1% (95% CI, 89.3%-97.1%) and a sensitivity of 61.9% (95% CI, 38%-82%). Accuracy did not correlate with lesion location, gastric luminal visibility, examiner case volume, or examination time. Of the remaining 168 patients, 94% had minor and mostly multiple lesions; the capsule made a correct diagnosis in 88.1% (95% CI, 82.2%-92.6%), with gastric visibility and lesion location in the proximal stomach having significant influence. All patients preferred capsule gastroscopy. In a prospective and strictly blinded study, magnetically guided capsule gastroscopy was shown to be feasible in clinical practice and was clearly preferred by patients. Improvements in capsule technology may render this technique a future alternative to gastroscopy.
    No preview · Article · Mar 2014 · Journal of clinical gastroenterology
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    Full-text · Article · May 2013 · Gastrointestinal Endoscopy
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    ABSTRACT: Objective: There is no comparative study of electronic radial endoscopic ultrasonography (ER-EUS) and electronic curvilinear EUS (EC-EUS). The aim of this study was to compare the accuracy of ER-EUS and EC-EUS for detecting pancreatic malignancies. Methods: This was a retrospective review of the patients who had EUS assessment from September 2008 to December 2011 for suspicious pancreatic tumors. Sensitivity, specificity, and area under the ROC curve to detect pancreatic malignancies were calculated and compared between the ER-EUS and EC-EUS cohort. The final diagnosis of pancreatic malignancy was based on pathology, or the consensus of patient's clinical course and multimodal imaging tests. Results: Two hundred twenty-one patients were included and divided into two cohorts: ER-EUS (n = 139) and EC-EUS (n = 82) cohorts. With propensity score matching method, 70 cases in each cohort were selected for the comparison. There was no significant difference in sensitivity, specificity, and area under the ROC curve to detect pancreatic malignancy between ER-EUS and EC-EUS cohort (88.5 vs. 100%, 88.6 vs. 90.9%, 0.8855 vs. 0.9545). Conclusion: ER-EUS and EC-EUS provided similar accuracy for the detection of pancreatic malignancies. In view of similar diagnostic results of ER-EUS and EC-EUS for the detection of pancreatic malignancy, and the advantage of being able to perform FNA with EC-EUS, EC-EUS may be the preferred choice.
    No preview · Article · Sep 2012 · Scandinavian Journal of Gastroenterology
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    ABSTRACT: Autoimmune pancreatitis (AIP) is often misdiagnosed as pancreatic carcinoma (PC) despite recent advances in imaging tests. The aim of the study was to evaluate whether the quantitative perfusion analysis using software "Time intensity curve" with contrast-enhanced harmonic EUS (CH-EUS) facilitate the differentiation of AIP from PC. Consecutive patients with focal AIP and pancreatic carcinoma who underwent CH-EUS from January 2009 to September 2010 were analyzed. CH-EUS was performed with intravenous administration of an ultrasonographic contrast (Sonazoid) and electronic radial echoendoscope. The graph of time intensity curve (TIC) for pancreatic mass was generated to depict the changes in signal intensity over time within the region of interest (ROI). ROI was placed to cover an area with a pancreatic mass lesion. Based on the analysis of TIC, base intensity before injection (BI), peak intensity (PI), time to peak, and maximum intensity gain (MIG: PI-BI) were calculated. Eight patients with focal AIP and twenty-two patients with PC were evaluated by TIC. PI and MIG of mass lesion of AIP were significantly higher than that of PC (21.4 dB vs. 9.6 dB, 17.5 vs. 6.6). Receiver operating characteristics analysis yielded an optimal MIG cutoff value of 12.5 with high sensitivity and specificity. Pancreatic mass lesions of AIP and PC exhibited markedly different patterns with the TIC. This novel diagnostic modality using TIC generated by CH-EUS might offer an opportunity to improve accuracy in the differential diagnosis between pancreatic mass lesion of AIP and PC.
    No preview · Article · Apr 2012 · Scandinavian Journal of Gastroenterology
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    ABSTRACT: Passive video capsule endoscopy is the criterion standard for small-bowel exploration but cannot be used for the large gastric cavity. We report the first blinded comparative clinical trial in humans comparing a magnetically guided capsule endoscope (MGCE) and a conventional high-definition gastroscope. To assess the potential of gastric examination with a guided capsule. Blinded, nonrandomized comparative study. Single endoscopy center. The trial involved 61 patients included in a blinded capsule and gastroscopy comparative study. MGCE examination was performed 24 hours after patients had undergone gastroscopy. To remove food residue or mucus, patients drank 900 mL of water in 2 portions. Then to provide the air-water interface required by the guidance system, they drank 400 mL of water at 35°C. Visualization of the gastric pylorus, antrum, body, fundus, and cardia was evaluated as complete in 88.5%, 86.9%, 93.4%, 85.2%, and 88.5% of patients, respectively. Of gastric lesions, 58.3% were detected by both gastroscopy and MGCE at immediate assessment and review of recorded data. Capsule examination missed 14 findings and gastroscopy missed 31 findings seen with MGCE. Overall diagnostic yield was similar for both modalities. Pilot study. Diagnostic results were similar for the 2 methods. After some technical difficulties related to gastric expansion or presence of mucus had been overcome, this study opened a new field for noninvasive gastric examination in countries where high gastric cancer incidence demands a screening tool.
    No preview · Article · Dec 2011 · Gastrointestinal endoscopy
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    ABSTRACT: Abstract Introduction: We developed a new offset-tip papillotome to facilitate biliary cannulation and reduce the incidence of unintended contrast injection into the pancreatic duct during ERCP. The aim of the present retrospective cohort study was to evaluate the utility of the novel offset-tip papillotome in achievement of biliary cannulation, and prevention of unintended contrast injection into the pancreatic duct during ERCP, compared with a standard straight-tip catheter. Material and methods: Patients with native papilla who required biliary ERCP were retrospectively reviewed. Biliary ERCPs were performed by two experienced endoscopists using either the offset-tip papillotome or a standard catheter. Patients in whom ERCP involved fellows in training were excluded. Results: Eighty-five patients were included and divided into two cohorts: The offset-tip papillotome (OT; n = 40) and the standard straight-tip cohort (ST; n = 45). Biliary cannulation success rates in OT and ST cohort were 92.5% and 88.9%, respectively. The frequency of unintended contrast injection into the pancreatic duct and time to biliary cannulation of the OT cohort during biliary cannulation were significantly less than those of the ST cohort (0.56 vs. 1.65 times and 103.3 vs. 287.9 seconds). Conclusion: The novel offset-tip papillotome could reduce the incidence of unintended contrast injection into the pancreatic duct and the time to biliary cannulation.
    No preview · Article · Nov 2011 · Minimally invasive therapy & allied technologies: MITAT: official journal of the Society for Minimally Invasive Therapy
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    Hiroyuki Aihara · Keiichi Ikeda · Hisao Tajiri
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    ABSTRACT: Small-bowel lesions responsible for obscure GI bleeding are often accompanied by vascular abnormalities. Image-enhanced capsule endoscopy could be advantageous in detecting these abnormalities. To evaluate the image representation performance of the contrast capsule. Feasibility study. University hospital. Consecutive patients with obscure GI bleeding swallowed the contrast capsule. Image representation performance of the contrast capsule and the appearance of small-bowel lesions in image-enhanced capsule endoscopy. Twenty patients (16 males and 4 females) underwent capsule endoscopy during the study period. Small-bowel abnormality was detected, including 5 cases of multiple erosions or ulcers, 1 case of Peutz-Jeghers syndrome, and 1 case of angiectasia. The contrast capsule visualized the lesions with high vascularity in a dark green color with a strong color contrast compared with the surrounding normal mucosa, which appeared as a brownish color. Small, single-center, nonrandomized study. This feasibility study demonstrated the image representation characteristics of the contrast capsule. The diagnostic yield of this technology should be investigated in a future randomized trial.
    Full-text · Article · Jun 2011 · Gastrointestinal endoscopy

  • No preview · Article · Apr 2011 · Gastrointestinal Endoscopy

  • No preview · Article · Apr 2011 · Gastrointestinal Endoscopy
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    ABSTRACT: The greater omentum is the largest depot of visceral fat, and recent studies implicate removal of omental fat as a therapeutic option for metabolic syndrome (MS). This study evaluated the technical feasibility of reducing omental fat by using ultrasound-assisted liposuction (UAL) in porcine models. We removed as much omental adipose tissues as possible with a novel ultrasonic aspirator specifically designed for visceral liposuction that was inserted into the peritoneal cavity via the bilateral hypochondrial trocars. The greater part of the omental surface was emulsified and suctioned within 12.4 ± 9.2 (mean ± SD) min. In the survival study, all animals survived for two weeks without clinically evident complications following UAL. Histological examinations confirmed a substantial reduction in omental fat in pigs subjected to UAL. In conclusion, the pilot animal study conducted here demonstrated the technical feasibility of omental liposuction. UAL thus has potential as a relatively non-invasive liposuction approach to treat MS by selectively reducing the visceral fat content of the greater omentum.
    No preview · Article · Mar 2011 · Minimally invasive therapy & allied technologies: MITAT: official journal of the Society for Minimally Invasive Therapy
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    ABSTRACT: The advent of natural orifice transluminal endoscopic surgery (NOTES) has accelerated the development of new technology in the field of GI endoscopy. Various suturing devices or multitasking platforms are expected to be valuable for endoluminal surgery as well as for NOTES. To evaluate a new multitasking platform in performing endoscopic full-thickness resection (EFTR). Bench-top comparison study. Research laboratory study of 10 ex vivo porcine models. Ten EFTRs (5 with a double-channel endoscope vs 5 with a new multitasking platform) assisted with percutaneous gastric lifting. Each group was given the task of resecting a full-thickness specimen of the gastric wall including a pseudolesion 10 mm in diameter with an effective margin. Outcome measurements included time to perform the procedure, accuracy of the resection, and efficiency for the task. Accuracy was assessed according to variability of the surgical margin and misalignment between the mucosal layer and the seromuscular layer. Efficiency was assessed according to the duty ratio, which is the percentage of time spent for the main purposes compared with the total procedure time. Mean diameter of the specimen was not significantly different between the groups. All other assessment items were significantly superior in group B to those in group A (P < .05). Ex vivo animal model study. We were able to perform EFTR procedures precisely and effectively by using a new multitasking platform compared with use of a conventional endoscope in a porcine model. A multitasking platform developed for NOTES procedures would be useful for advanced endoluminal surgery such as endoscopic submucosal dissection or EFTR as well as NOTES.
    No preview · Article · Nov 2010 · Gastrointestinal endoscopy
  • Kazuki Sumiyama · Keiichi Ikeda · Hisao Tajiri
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    ABSTRACT: Natural orifice translumenal endoscopic surgery (NOTES) has attracted great interests from both of surgeons and gastroenterologists as a next generation minimally invasive surgery completely eliminating need for skin incision, and also a paradigm shift for flexible endoscopy to explore new frontiers beyond the confines of the gut wall. Various translumenal routes have been studied to access into the peritoneal cavity, and pros and cons of each procedure have been clarified. Although clinical introduction of NOTES has been spreading very slowly, technologies growing from the concept of NOTES may resolve an array of challenges currently associated with endoscopic surgery and flexible endoscopy. There is little dought that NOTES would yield rewards not only to surgeons, but also to gastroenterologists.
    No preview · Article · Jul 2010 · Nippon rinsho. Japanese journal of clinical medicine
  • Keiichi Ikeda · Kazuki Sumiyama · Hisao Tajiri

    No preview · Article · Apr 2009 · Gastrointestinal Endoscopy
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    ABSTRACT: It is challenging to optimally sample the muscularis propria endoscopically for the diagnosis of muscle layer diseases, especially for motility disorders resulting from neuroenteric dysfunction. Ultramagnification in vivo imaging of the muscularis mucosa and ex vivo identification of myenteric neuronal elements by confocal microscopy. Ex vivo and in vivo porcine animal studies. Short-term study in an animal laboratory. The muscularis propria in the stomach and esophagus was accessed by resecting the mucosal layer with endoscopic submucosal dissection or cap EMR techniques or by creating a submucosal space by the submucosal endoscopy with mucosal flap technique. The muscularis propria was stained with Nissl stains and 2 types of neuronal molecular stains. The muscular layer was imaged with the endocytoscope in vivo. The muscularis stained with molecular-based stains was also evaluated with a confocal microscope. Cellular microstructures resembling spindle-shaped smooth muscle cells were visualized by endocytoscopy in vivo. Confocal endoscopic microscopy demonstrated that in vivo topical application of neuronal molecular stains successfully stained the muscularis and specifically highlighted neuron-like cells. Animal model pilot study. In vivo endoscopic histologic evaluation of the muscularis propria is technically feasible and easy. Minimally invasive advanced endoscopic imaging may be useful for the diagnosis and study of neuroenteric disorders at the level of the muscularis propria, avoiding surgical full-thickness tissue sampling.
    No preview · Article · Mar 2009 · Gastrointestinal endoscopy
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    ABSTRACT: Postoperative pancreatic fistula remains a major complication after pancreatic surgeries. To prevent pancreatic fistula, one of the employed management strategies is pancreatic duct stenting. The purpose of this study was to evaluate the efficacy and safety of preoperative pancreatic stenting to prevent pancreatic fistula after surgery. Subjects comprised 18 consecutive patients who underwent pancreatic surgeries. Patients were divided into 2 groups: stenting group (n=7); and non-stenting group (n=11). Complications after stent placement were analyzed. Compared parameters between groups included background, incidence and grading of pancreatic fistula as judged by international study group of pancreatic fistula (ISGPF) criteria, duration until drain removal, and mean maximum level of drain amylase. Two patients displayed mild pancreatitis with high serum amylase levels after stenting. No significant differences in background or any other compared parameters to assess drainage effect were identified between stenting and non-stenting groups. Complications related to placement of the stent tube occurred in 4 patients with tube occlusion or cholestasis. Although drainage effect in the stenting group was compared with that in the non-stenting group, no obvious effect was obtained. This procedure seems to require further investigation on indications for postoperative drainage to decrease the incidence of pancreatic fistula.
    Full-text · Article · Jul 2008 · International Journal of Surgery (London, England)
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    ABSTRACT: The purpose of this study was to introduce our procedure of limited pancreatic resection with preoperative pancreatic duct stenting to prevent complications. Subjects comprised 6 patients with neoplasm who underwent preoperative pancreatic stenting. Pancreatic stents were placed within 7 days before elective surgery. After intraoperative ultrasonography, the relationship between the main pancreatic duct (MPD) and the lesion was confirmed by measuring the distance. Partial resection was surrendered if a sufficient margin of excised tumor was not obtained or injury to the MPD was likely to occur. Branches of pancreatic duct recognized were ligated as much as possible. Mild pancreatitis was present after stenting in 2 patients. Three patients actually underwent partial resection. In patients with partial resection, enhanced visualization of the MPD was useful for deciding the operative procedure and prevented iatrogenic injury to the MPD during dissection. Pancreatic duct stenting prior to pancreatic surgery seems useful as a guide for determining the feasibility of limited pancreatic resection and to prevent missing injury to the MPD.
    No preview · Article · Jul 2008 · Digestive surgery
  • Paul Swain · Keiichi Ikeda
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    ABSTRACT: IntroductionEndoscope DevelopmentNext Steps Toward the FuturePerspectives for the FutureReferences
    No preview · Chapter · Apr 2008

Publication Stats

1k Citations
242.93 Total Impact Points


  • 2014
    • Showa University
      Shinagawa, Tōkyō, Japan
  • 2002-2014
    • The Jikei University School of Medicine
      • Department of Endoscopy
      Edo, Tokyo, Japan
  • 2008
    • University Medical Center Utrecht
      • Department of Gastroenterology and Hepatology
      Utrecht, Utrecht, Netherlands
  • 2005-2006
    • Imperial College Healthcare NHS Trust
      Londinium, England, United Kingdom