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Dive into the research topics where Hirobumi Toyoizumi is active.

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Featured researches published by Hirobumi Toyoizumi.


Gastrointestinal Endoscopy | 2010

Magnifying endoscopy with narrow-band imaging achieves superior accuracy in the differential diagnosis of superficial gastric lesions identified with white-light endoscopy: a prospective study

Masayuki Kato; Mitsuru Kaise; Jin Yonezawa; Hirobumi Toyoizumi; Noboru Yoshimura; Muneo Kawamura; Hisao Tajiri

BACKGROUND Conventional, white-light imaging endoscopy (WLE) results in a significant number of misdiagnoses in early gastric cancer. Magnifying endoscopy combined with narrow-band imaging (ME-NBI) is more accurate in the diagnosis of gastric cancer when the diagnostic triad of the disappearance of fine mucosal structure, microvascular dilation, and heterogeneity is used. OBJECTIVE The aim of the present study was to evaluate the superiority of ME-NBI in the differential diagnosis of superficial gastric lesions identified with conventional WLE. DESIGN Prospective, comparative study. SETTING Single academic center. PATIENTS This study involved patients who underwent WLE and ME-NBI for surveying synchronous or metachronous cancers because they had a high risk of gastric cancer. INTERVENTION Patients with superficial gastric lesions that were diagnosed by WLE as cancer or non-cancer with a slight suspicion of cancer were prospectively enrolled in the study. ME-NBI was used to further characterize lesions picked up with WLE. MAIN OUTCOME MEASUREMENTS Sensitivity and specificity for the diagnosis of gastric cancer, with pathology as the criterion standard. RESULTS A total of 201 lesions (mean diameter [+/- SD] 7.0 +/- 4.0 mm) from 111 patients (98 men, 13 women; mean age 66.3 years) were evaluated. Fourteen of the 201 lesions were pathologically proven as gastric cancer; the others were noncancerous lesions. The sensitivity and specificity for ME-NBI diagnosis with the use of the triad (92.9% and 94.7%, respectively) were significantly better than for WLE (42.9% and 61.0%, respectively; P < .0001). LIMITATIONS Single center and a highly selected population at high risk for gastric cancer. CONCLUSION ME-NBI achieved superior accuracy in the differential diagnosis of superficial gastric lesions identified with WLE. Thus, ME-NBI may increase the diagnostic value of endoscopy in a population at high risk of gastric cancer.


Gastrointestinal Endoscopy | 2009

Trimodal imaging endoscopy may improve diagnostic accuracy of early gastric neoplasia: a feasibility study

Masayuki Kato; Mitsuru Kaise; Jin Yonezawa; Kenichi Goda; Hirobumi Toyoizumi; Noboru Yoshimura; Muneo Kawamura; Hisao Tajiri

BACKGROUND A considerable number of superficial gastric neoplasias are overlooked with conventional white light imaging (WLI) endoscopy. OBJECTIVE The aim was to investigate the diagnostic potential of trimodal imaging endoscopy (TME), which combines WLI, autofluorescence imaging (AFI), and narrow-band imaging (NBI), for superficial gastric neoplasia. DESIGN Feasibility study. SETTING Single academic center. PATIENTS Sixty-two patients with or without gastric neoplasia. INTERVENTION Each patient serially assessed with WLI, AFI, and magnifying endoscopy with NBI (ME-NBI) by an endoscopist blinded for clinical information. ME-NBI over WLI and AFI was designated as TME. Histopathology of biopsy and ESD specimens was evaluated and used as the gold standard. MAIN OUTCOME MEASUREMENTS Sensitivity and specificity of endoscopic diagnosis of pathology-proven neoplasia by per-patient and per-lesion analyses. RESULTS The study included 47 pathology-proven neoplasias and 44 pathology-proven nonneoplasias that were detected as neoplasias with any of the modalities. By a per-lesion analysis, the sensitivity of TME (89.4%) was higher than that of WLI (76.6%) and AFI (68.1%). The specificity of TME (98.0%) was higher than that of WLI (84.3%) and AFI (23.5%). By a per-patient analysis, the sensitivity of TME (90.9%) was higher than that of WLI (75%) and AFI (68.2%). The specificity of TME (100%) was higher than that of WLI (72.2%) and AFI (44.4%). LIMITATIONS Case-enriched population at a single center. CONCLUSIONS Higher diagnostic accuracy of TME over conventional WLI indicates the feasibility of TME for the efficacious diagnosis of early gastric neoplasia.


Gastrointestinal Endoscopy | 2009

Ultrathin endoscopy versus high-resolution endoscopy for diagnosing superficial gastric neoplasia

Hirobumi Toyoizumi; Mitsuru Kaise; Hiroshi Arakawa; Jin Yonezawa; Masayuki Kato; Noboru Yoshimura; Kenichi Goda; Hisao Tajiri

BACKGROUND Ultrathin endoscopy (UTE) is an acceptable and cost-effective alternative to EGD with the patient under sedation, although the diagnostic accuracy of UTE is not well established. OBJECTIVE To compare the diagnostic accuracy of UTE and high-resolution endoscopy (HRE) for superficial gastric neoplasia. DESIGN Prospective comparative study. SETTING Academic center. PATIENTS AND INTERVENTIONS Patients with or without superficial gastric neoplasia underwent peroral UTE and HRE, back-to-back in a random order while under standard sedation. The procedures were performed by 2 endoscopists who were blinded to the clinical information. MAIN OUTCOME MEASUREMENTS The rate of missed lesions and misdiagnosis, sensitivity, and specificity for the diagnosis of gastric neoplasia when using pathology as the reference standard. RESULTS In total, 126 lesions (41 superficial gastric neoplasias, 85 nonneoplastic lesions) were recorded in 57 enrolled patients. For the diagnosis of gastric neoplasia, the sensitivity of UTE (58.5%) was significantly (P = .021) lower than that of HRE (78%), and the specificity of UTE (91.8%) was significantly (P = .014) lower than that of HRE (100%). The rate of missed lesions and misdiagnosis of gastric neoplasias when using UTE (41.5%) was significantly (P > .001) higher than that of HRE (22.0%). The corresponding rate of neoplasias at the proximal portion (fornix and corpus) when using UTE (29%) was significantly (P = .002) higher than that of HRE (7.2%), although the rates of neoplasias at the distal portion (angulus and antrum) were comparable for UTE and HRE. LIMITATION Small sample numbers in an enriched population. CONCLUSIONS The diagnostic accuracy of UTE is significantly lower than that of HRE for superficial gastric neoplasia, and this difference is particularly striking for neoplasias in the proximal stomach. For UTE to be used as an alternative modality, improvements in optical quality and the incorporation of additional procedures, including close-range observations and chromoendoscopy, are required to enhance visualization.


Gastrointestinal Endoscopy | 2014

A double-blind, block-randomized, placebo-controlled trial to identify the chemical assistance effect of mesna submucosal injection for gastric endoscopic submucosal dissection

Kazuki Sumiyama; Hirobumi Toyoizumi; Tomohiko R. Ohya; Akira Dobashi; Shoryoku Hino; Masakuni Kobayashi; Kenichi Goda; Hiroo Imazu; Yumi Kawakita; Tomohiko Kato; Hisao Tajiri

BACKGROUND Previous animal studies and a pilot clinical trial demonstrated that submucosal injection of a thiol compound called mesna could chemically soften connective tissues and thus facilitate endoscopic submucosal dissection (ESD). OBJECTIVE To evaluate whether mesna injection could reduce procedural times for gastric ESD. DESIGN Double-blind, block-randomized, controlled trial. SETTING University hospital. PATIENTS A total of 101 patients with superficial gastric cancer indicated for ESD were enrolled and randomly assigned to either the mesna or control (saline solution) group. INTERVENTION Traditional ESD was performed with a single bolus injection of mesna or saline solution. MAIN OUTCOME MEASUREMENTS Time for submucosal dissection (TSD). RESULTS En bloc resection was achieved for all lesions in the mesna group (53/53) and 51 of 52 lesions (98.08%) in the control group. TSD was not statistically different between the groups (18.62 ± 13.9 [mean ± SD] minutes for the mesna group and 24.58 ± 24.55 [mean ± SD] minutes for the control group; P = .128), and there were fewer time-consuming cases (times over 30 minutes) in the mesna group compared with controls (7/53 vs 15/52; P = .049). Multivariate regression analysis demonstrated that use of mesna, specimen size, and the presence of fibrous scars were significantly correlated with TSD (P < .05). LIMITATIONS Single-center study. CONCLUSION TSD was not significantly different between the mesna and control injection groups, but multivariate analysis indicated that mesna injection reduced procedural challenges associated with the submucosal dissection. ( CLINICAL TRIAL REGISTRATION NUMBER UMIN000003786.).


Gastroenterology Research and Practice | 2015

Narrow-Band Imaging Magnifying Endoscopy versus Lugol Chromoendoscopy with Pink-Color Sign Assessment in the Diagnosis of Superficial Esophageal Squamous Neoplasms: A Randomised Noninferiority Trial

Kenichi Goda; Akira Dobashi; Noboru Yoshimura; Masayuki Kato; Hiroyuki Aihara; Kazuki Sumiyama; Hirobumi Toyoizumi; Tomohiro Kato; Masahiro Ikegami; Hisao Tajiri

Previous studies have shown the high diagnostic accuracy of narrow-band imaging magnifying endoscopy (NBI-ME) and Lugol chromoendoscopy with pink-color sign assessment (LCE-PS) for superficial esophageal squamous cell carcinoma (SESCC). However, there has been no controlled trial comparing these two diagnostic techniques. We conducted a randomized noninferiority trial to compare the diagnostic accuracy of NBI-ME and LCE-PS. We recruited patients with, or with a history of, squamous cell carcinoma in the head and neck region or in the esophagus. They were randomly assigned to either NBI-ME or LCE-PS. When lesions > 5 mm in diameter were found as brownish areas on NBI or as Lugol-voiding lesions (LVL), they were evaluated to determine whether they are SESCC on the basis of the findings of NBI-ME or PS in the LVL. NBI-ME and LCE-PS were completed in 147 patients each. There was no significant difference in all diagnostic values between the two techniques. Compared with LCE-PS, NBI-ME showed a significantly shorter examination time but a larger number of misdiagnosed lesions especially in patients with many irregularly shaped multiform LVLs. Compared with LCE-PS, NBI-ME might be similarly accurate and less invasive, but less reliable in patients with many LVLs, in the diagnosis of SESCC.


Scandinavian Journal of Gastroenterology | 2013

Magnifying endoscopy combined with narrow band imaging may help to predict neoplasia coexisting with gastric hyperplastic polyps

Hiroshi Horiuchi; Mitsuru Kaise; Hiroko Inomata; Masayuki Kato; Hirobumi Toyoizumi; Kenichi Goda; Hiroshi Arakawa; Masahiro Ikegami; Ryoji Kushima; Hisao Tajiri

Abstract Background and study aim. Although focal cancer occasionally coexists with gastric hyperplastic polyps, previous studies have reported that white light endoscopy (WLE) and biopsy sampling cannot effectively predict the coexistence of cancer. The aim of this study was to elucidate efficacious predictors for cancer coexistence. Patients and methods. This retrospective single academic center study analyzed consecutive patients with gastric polyps diagnosed as hyperplastic before endoscopic resection. Using an image catalog of WLE and magnifying endoscopy combined with narrow band imaging (ME-NBI) performed as part of the preresection work-up, three endoscopists independently assessed the coexistence of cancer and the presence of predefined ME-NBI findings in the microvasculature (MV) and fine mucosal structure (FMS). Results. Twelve of 64 gastric polyps (19%) resected from 51 patients enrolled in the study showed the coexistence of neoplasia. Polyps with coexisting neoplasia were significantly larger than those without (22.6 ± 10.1 vs. 15.5 ± 7.7 mm, respectively). Multivariate analysis of factors significantly associated with the coexistence of neoplasia identified lesion size and three specific endoscopic findings, that is, WLE diagnosis of cancer coexistence, ME-NBI findings of abnormal MV and micrification (size reduction) of the FMS. Combining lesion size (≥20 mm) and ME-NBI findings of FMS micrification had a diagnostic accuracy of 100% sensitivity and 58% specificity for coexisting neoplasia. However, combinations of WLE diagnosis and any other criteria could not achieve a diagnostic sensitivity of 100%. Conclusion. ME-NBI enhances the prediction of cancer coexistence in gastric hyperplastic polyps, with lesion size (≥20 mm) and FMS micrification the most effective predictive findings.


Diseases of The Esophagus | 2014

Clinicopathological features of narrow-band imaging endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms.

Kenichi Goda; Akira Dobashi; Noboru Yoshimura; M. Chiba; A. Fukuda; Yutaka Nakao; Tomohiko R. Ohya; Y. Sasaki; Masayuki Kato; Hiroyuki Aihara; Kazuki Sumiyama; Hirobumi Toyoizumi; Tomohiro Kato; Hisao Tajiri; Masahiro Ikegami

To reveal clinicopathological features of narrow-band imaging (NBI) endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms. If a lesion diameter was smaller or same compared with a width of closed biopsy forceps, a lesion was defined to be an ultraminute lesion. Twenty-five consecutive patients with 33 ultraminute esophageal lesions that were removed by endoscopic mucosal resection were included in the present study. We conducted two questionnaire surveys of six endoscopists by their retrospective review of endoscopic still images. The six endoscopists evaluated the endoscopic findings of the ultraminute lesions on still images taken by conventional white-light imaging endoscopy and non-magnified NBI endoscopy in the first questionnaire, and taken by magnified NBI endoscopy in the second questionnaire. An experienced pathologist who was unaware of any endoscopic findings made histological diagnosis and evaluated immunoexpression of p53 and Ki67. The 33 ultraminute lesions were all determined to be either 11 high-grade intraepithelial neoplasias (HGIENs) or 22 low-grade intraepithelial neoplasias (LGIENs). The tumor diameters were histologically confirmed to be <3 mm. All of the ultraminute tumors were visualized as unstained areas and brownish areas by real-time endoscopy with Lugol dye staining and non-magnified NBI endoscopy, respectively. All of the ultraminute IENs were visualized as brownish areas by real-time non-magnified NBI endoscopy. Three of the 25 patients with the ultraminute IENs (12%) had multiple brownish areas (more than several areas) in the esophagus on real-time non-magnified NBI endoscopy. All of the ultraminute IENs were visualized as unstained areas by real-time Lugol chromoendoscopy. Twenty of the 25 patients (80%) had multiple unstained areas (more than several areas) in the esophagus on real-time Lugol chromoendoscopy. The first questionnaire survey revealed that a significantly higher detection rate of the ultraminute IENs on non-magnified NBI endoscopy images compared with conventional white-light imaging endoscopy ones (100% vs. 72%, respectively: P < 0.0001). The second questionnaire survey revealed that presence rates of any magnified NBI endoscopy findings were not significantly different between HGIENs and LGIENs. Proliferation, dilation, and various shapes of intrapapillary capillary loops indicated remarkably high presence rates of more than 90% in both HGIENs and LGIENs. Six of 22 LGIENs (27%) and 3 of 11 HGIENs (27%) show a positive expression for p53. None of peri-IEN epithelia was positive for p53. A mean of Ki67 labeling index of LGIENs was 33% and that of HGIENs 36%. Ki67 labeling index was significantly greater in the LGIENs and HGIENs compared with that in the peri-IEN epithelia. There were no significant differences in p53 expression and Ki67 labeling index between the HGIENs and LGIENs. Non-magnified/magnified NBI endoscopy could facilitate visualization and characterization of ultraminute esophageal squamous IENs. The ultraminute HGIENs and LGIENs might have comparable features of magnified NBI endoscopy and immunohistochemistry.


Endoscopy | 2016

Dual-focus versus conventional magnification endoscopy for the diagnosis of superficial squamous neoplasms in the pharynx and esophagus: a randomized trial.

Kenichi Goda; Akira Dobashi; Noboru Yoshimura; Hiroyuki Aihara; Masayuki Kato; Kazuki Sumiyama; Hirobumi Toyoizumi; Tomohiro Kato; Hiroki Saijo; Masahiro Ikegami; Hisao Tajiri

BACKGROUND AND STUDY AIMS Conventional magnification narrow-band imaging (CM-NBI) endoscopy has demonstrated high diagnostic accuracy for superficial squamous neoplasms in the pharynx and esophagus. This study aimed to evaluate the diagnostic utility of the newly developed dual-focus NBI (DF-NBI) compared with that of CM-NBI. PATIENTS AND METHODS We recruited patients with squamous cell carcinoma (SCC) in the head and neck, or esophagus, or with a history of SCC. The primary endpoint of this prospective controlled non-inferiority trial was the sensitivity of DF-NBI and CM-NBI for detecting superficial carcinoma in the pharynx and esophagus. Secondary endpoints included other diagnostic values and the resolving power of each endoscope. Superficial carcinoma was defined as high grade dysplasia and SCC invading up to the submucosal layer. RESULTS The study included 93 patients. A total of 28 superficial carcinomas were detected in the pharynx and esophagus. The sensitivities of DF-NBI and CM-NBI for superficial carcinoma were 82 % and 71 %, respectively. The lower limit of the 90 % confidence interval for the difference between the sensitivities exceeded the non-inferiority threshold. The specificity and overall accuracy of DF-NBI vs. CM-NBI were 93 % vs. 90 % and 91 % vs. 86 %, respectively (both non-significant differences). The maximum resolving power of a conventional magnification endoscope was significantly higher than a dual-focus endoscope (7.2 µm vs. 11.6 µm: P < 0.001). CONCLUSIONS The findings indicate the non-inferiority of DF-NBI versus CM-NBI in detecting superficial carcinoma in the pharynx and esophagus. DF-NBI appears to have a resolving power that, although significantly lower, is sufficient to achieve high diagnostic accuracy, comparable to that of CM-NBI.University Hospital Medical Information Network (UMIN, No. 000007585).


Journal of Medical Case Reports | 2012

Early duodenal adenocarcinoma resembling a submucosal tumor cured with endoscopic resection: a case report

Akira Dobashi; Kenichi Goda; Noboru Yoshimura; Kazuki Sumiyama; Hirobumi Toyoizumi; Shoichi Saito; Tomohiro Kato; Hiroki Ishikawa; Katsuhiko Yanaga; Hisao Tajiri; Masahiro Ikegami

IntroductionPrimary adenocarcinomas resembling submucosal tumors are rare in the gastrointestinal tract. Almost all the submucosal tumor-like adenocarcinomas previously reported invaded the submucosa or deeper. Therefore, submucosal tumor-like lesions are usually treated by surgical resection, and those that arise in the duodenum have been treated by pancreaticoduodenectomy.Case presentationA 65-year-old Japanese man was diagnosed with a submucosal tumor-like adenocarcinoma in his duodenum. We considered it possible that the tumor invasion was limited to the mucosal or submucosal layers and could be removed by endoscopic resection. Tumor histopathology revealed a well-differentiated adenocarcinoma confined to the muscularis mucosae with no lymphovascular invasion. Complete resection of the carcinoma was achieved and there has been no recurrence three years after endoscopic resection.ConclusionsWe suggest that submucosal tumor-like adenocarcinomas arising in nonampullary duodenal sites should be diagnosed carefully with a view to possible endoscopic resection.


Digestive Diseases and Sciences | 2014

Contrast-Enhanced Harmonic Endoscopic Ultrasonography in the Differential Diagnosis of Gallbladder Wall Thickening

Hiroo Imazu; Naoki Mori; Keisuke Kanazawa; Masafumi Chiba; Hirobumi Toyoizumi; Yuichi Torisu; Seita Koyama; Shoryoku Hino; Tiing Leong Ang; Hisao Tajiri

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Hisao Tajiri

Jikei University School of Medicine

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Kenichi Goda

Jikei University School of Medicine

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Noboru Yoshimura

Jikei University School of Medicine

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Akira Dobashi

Jikei University School of Medicine

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Kazuki Sumiyama

Jikei University School of Medicine

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Tomohiro Kato

Jikei University School of Medicine

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Masahiro Ikegami

Jikei University School of Medicine

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Mitsuru Kaise

Jikei University School of Medicine

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Tomohiko R. Ohya

Jikei University School of Medicine

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