Atsushi Imagawa

Dr. Atsushi Imagawa

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Research Focus & Metrics

Academic Career Length

37Years (1990-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2015 in World Journal of Gastrointestinal Endoscopy
Verified
Journal Article
Open access
MIMasaya Iwamuro
Masaya Iwamuro
HOHiroyuki Okada
Hiroyuki Okada
KMKazuhiro Matsueda
Kazuhiro Matsueda
TITomoki Inaba
Tomoki Inaba
CKChiaki Kusumoto
Chiaki Kusumoto
KYKazuhide Yamamoto
Kazuhide Yamamoto
Review of the diagnosis and management of gastrointestinal bezoars

20 October 2006 in Endoscopy
Verified
Journal Article
Closed access
PDF file
AIAtsushi Imagawa
Atsushi Imagawa
HOH. Okada
H. Okada
YKY. Kawahara
Y. Kawahara
RTR. Takenaka
R. Takenaka
JKJ. Kato
J. Kato
YSY. Shiratori
Y. Shiratori
Background and study aims: Endoscopic submucosal dissection (ESD) is a new method for the curative treatment of early gastrointestinal neoplasms, which was developed in order to increase the en bloc and R0 resection rate, especially for lesions larger than 20 mm in diameter. Drawbacks of ESD include the fact that it is technically a substantially more difficult procedure and that it is associated with a higher perforation rate. A retrospective study was therefore carried out to analyze cases in relation to the procedure time and resection success, and these factors were correlated with the characteristics of the lesions. Patients and methods: From January 2002 to November 2005, 196 lesions in 185 patients with early gastric cancer were treated using ESD in our hospital. The rates of curative en bloc resection, the incidence of perforation, and the procedure times were analyzed in relation to lesion size (small, 20 mm or less in diameter; large, over 20 mm), location (upper, middle, or lower third of the stomach) and the presence or absence of ulceration. Results: The rate of curative en bloc resection was 84 % (93 % of the lesions overall were resected in one piece), with a perforation rate of 6.1 % (all perforations were managed endoscopically) and a mean procedure time of 68 min. The rate of curative en bloc resection differed significantly depending on the location of the lesion (upper vs. middle vs. lower, 74 % vs. 77 % vs. 91 %; P < 0.05), as well as on the size of the lesion (> 20 mm vs. 20 mm or less, 59 % vs. 89 %; P < 0.0001). There were also significant differences in the mean procedure times in relation to the location of the lesion (upper vs. middle vs. lower, 105 min vs. 81 min vs. 45 min; P < 0.0001) and the size of the lesion (> 20 mm vs. 20 mm or less, 124 min vs. 55 min; P < 0.0001), as well as the presence of ulceration (positive vs. negative, 97 min vs. 65 min; P < 0.05). With regard to perforation rates, significant differences were also observed in relation to the location of the lesion (upper vs. middle vs. lower, 22.6 % vs. 2.8 % vs. 3.2 %; P < 0.0005) and size of the lesion (> 20 mm vs. 20 mm or less, 16.2 % vs. 3.8 %; P < 0.005). No local recurrences of curatively resected lesions (n = 119) were observed after a follow-up period of 1 year. Conclusions: The difficulty of ESD depends on the location and size of the lesion, as well as on the presence of ulceration. We would recommend that trainees should begin by carrying out ESD on lesions with a diameter of less than 20 mm without ulceration that are located in the lower third of the stomach.

1 November 2008 in Gastrointestinal Endoscopy
Verified
Journal Article
Closed access
RTRyuta Takenaka
Ryuta Takenaka
YKYoshiro Kawahara
Yoshiro Kawahara
HOHiroyuki Okada
Hiroyuki Okada
KHKeisuke Hori
Keisuke Hori
MIMasafumi Inoue
Masafumi Inoue
KYKazuhide Yamamoto
Kazuhide Yamamoto

5 February 2007 in Alimentary Pharmacology & Therapeutics
Verified
Journal Article
Open access
PDF file
RTR. Takenaka
R. Takenaka
HOH. Okada
H. Okada
JKJ. Kato
J. Kato
CMC. Makidono
C. Makidono
SHS. Hori
S. Hori
YSY. Shiratori
Y. Shiratori
Summary: Background: Although Helicobacter pylori infection is closely associated with gastric cancer development, follow‐up studies after H. pylori eradication are still scarce.Aim: To clarify the cancer preventive effect of H. pylori eradication, with special attention to differences in effect according to histology.Methods: Patients who underwent H. pylori eradication therapy and were followed‐up endoscopically for at least 1 year were analysed. The incidence of gastric cancer and factors associated with cancer development were investigated.Results: A total of 1807 patients were enrolled. Six of 1519 H. pylori eradicated and five of 288 persistent subjects developed gastric cancer. Four of the eradicated subjects developed the intestinal type and two the diffuse type, while four of the persistent subjects developed the intestinal type and one the diffuse type. Kaplan–Meier analysis indicated a significantly lower incidence in eradicated patients than in persistent patients. The incidence of intestinal type was significantly lower than in eradicated patients, while the diffuse type could not be evaluated because of the low incidence.Conclusions: Helicobacter pylori‐eradicated patients had a reduced incidence of gastric cancer compared with H. pylori‐persistent patients, particularly the intestinal type, suggesting that H. pylori is strongly associated with intestinal‐type gastric cancer.

9 July 2004 in Endoscopy
Verified
Journal Article
Closed access
PDF file
MFM. Fujishiro
M. Fujishiro
NYN. Yahagi
N. Yahagi
KKK. Kashimura
K. Kashimura
YMY. Mizushima
Y. Mizushima
MOM. Oka
M. Oka
MOM. Omata
M. Omata
Background and Study Aims: Sodium hyaluronate (SH) is a promising submucosal injection solution during endoscopic mucosal resection, but its high cost is an obstacle to more widespread use. The aim of this study was to identify an appropriate low-cost SH solution by varying the molecular weight of SH and mixing various solutions with it. Materials and Methods: The viscoelasticity of various SH solutions was first measured. The concentrations of two 1 % SH preparations with different molecular weights (800 kDa and 1900 kDa) were adjusted to 0.5 %, 0.25 %, and 0.125 %, using 0.9 %/3.75 % normal saline (NS), 5 %/20 % dextrose water (DW), and a glycerin solution (Glyceol): 10 % glycerin with 0.9 % normal saline plus 5 % fructose. The ability of these SH solutions to create submucosal fluid cushions (SFCs) was then investigated in the stomachs of two live minipigs. Results: The 0.25 % 1900 kDa SH/NS solution and the 0.125 % 1900 kDa SH/20 % DW solution created a similar viscoelasticity to that of the 0.5 % 800 kDa SH/NS solution. The ability of these solutions to create SFCs was also similar. In addition, the 0.125 % 1900 kDa SH/Glyceol solution created similar SFCs, with a synergistic effect of increased viscoelasticity and the hypertonic nature of glycerin. Conclusions: A mixture of higher molecular weight sodium hyaluronate with a sugar solution (particularly 20 % dextrose), with or without glycerin, should be regarded as a cost-effective option for creating SFCs instead of the conventional SH solution made with the same amount of a 1 % 800 kDa SH preparation and normal saline.

5 October 2017 in British Journal of Cancer
Verified
Journal Article
Open access
PDF file
HSHiroyuki Sakae
Hiroyuki Sakae
HKHiromitsu Kanzaki
Hiromitsu Kanzaki
JNJunichiro Nasu
Junichiro Nasu
YAYutaka Akimoto
Yutaka Akimoto
KMKazuhiro Matsueda
Kazuhiro Matsueda
HOHiroyuki Okada
Hiroyuki Okada
Small bowel adenocarcinoma (SBA) is a rare malignancy that accounts for 1–2% of gastrointestinal tumours. We investigated the clinical characteristics, outcomes, and prognostic factors of primary SBA. We retrospectively analysed the characteristics and clinical courses of 205 SBA patients from 11 institutions in Japan between June 2002 and August 2013. The primary tumour was in the duodenum and jejunum/ileum in 149 (72.7%) and 56 (27.3%) patients, respectively. Sixty-four patients (43.0%) with duodenal adenocarcinoma were asymptomatic and most cases were detected by oesophagogastroduodenoscopy (EGD), which was not specifically performed for the detection or surveillance of duodenal tumours. In contrast, 47 patients (83.9%) with jejunoileal carcinoma were symptomatic. The 3-year survival rate for stage 0/I, II, III, and IV cancers was 93.4%, 73.1%, 50.9%, and 15.1%, respectively. Multivariate analysis revealed performance status 3–4, high carcinoembryonic antigen, high lactate dehydrogenase (LDH), low albumin, symptomatic at diagnosis, and stage III/IV disease were independent factors for overall survival (OS). Ten patients (18.5%) with stage IV disease were treated with a combination of resection of primary tumour, local treatment of metastasis, and chemotherapy; this group had a median OS of 36.9 months. Although most SBA patients were diagnosed with symptomatic, advanced stage disease, some patients with duodenal carcinoma were detected in early stage by EGD. High LDH and symptomatic at diagnosis were identified as novel independent prognostic factors for OS. The prognosis of advanced SBA was poor, but combined modality therapy with local treatment of metastasis might prolong patient survival.