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Dive into the research topics where Rikiya Hasegawa is active.

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Featured researches published by Rikiya Hasegawa.


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.


Journal of Hepato-biliary-pancreatic Sciences | 2016

Randomized controlled exploratory study comparing the usefulness of two types of metallic stents with different axial forces for the management of duodenal obstruction caused by pancreatobiliary cancer.

Kosuke Okuwaki; Mitsuhiro Kida; Hiroshi Yamauchi; Hiroshi Imaizumi; Shiro Miyawaza; Tomohisa Iwai; Hironori Masutani; Takaaki Matsumoto; Rikiya Hasegawa; Wasaburo Koizumi

Very few studies have examined effectiveness of duodenal stent placement (DSP) for duodenal obstruction (DO) caused specifically by pancreatobiliary cancer. We compared two types of stents with different axial forces (AF) for DO with pancreatobiliary cancer.


Digestive Diseases and Sciences | 2016

A Case Series: Outcomes of Endoscopic Biliary Self-Expandable Metal Stent for Malignant Biliary Obstruction with Surgically Altered Anatomy

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


Surgical Endoscopy and Other Interventional Techniques | 2018

Therapeutic peroral direct cholangioscopy using a single balloon enteroscope in patients with Roux-en-Y anastomosis (with videos)

Hiroshi Yamauchi; Mitsuhiro Kida; Kosuke Okuwaki; Shiro Miyazawa; Takaaki Matsumoto; Kazuho Uehara; Eiji Miyata; Rikiya Hasegawa; Toru Kaneko; Issaree Laopeamthong; Yang Lei; Tomohisa Iwai; Hiroshi Imaizumi; Wasaburo Koizumi


Revista Espanola De Enfermedades Digestivas | 2018

Analysis of the diagnostic yield of endoscopic ultrasonography-guided fine-needle aspiration in patients with a suspected pancreatic malignancy

Lei Yang; Tomohisa Iwai; Mitsuhiro Kida; Hiroshi Yamauchi; Kosuke Okuwaki; Hiroshi Imaizumi; Tohru Kaneko; Rikiya Hasegawa; Eiji Miyata; Koizumi Wasaburo


Pediatric Dermatology | 2018

A case of acinar cell carcinoma of the pancreas seen with intraductal papillary mucinous neoplasm

Naomi Waki; Eiji Miyata; Mitsuhiro Kida; Rikiya Hasegawa; Toru Kaneko; Hiroshi Yamauchi; Kosuke Okuwaki; Tomohisa Iwai; Hiroshi Imaizumi; Wasaburo Koizumi; Shigenori Ei; Masahiko Watanabe


Pediatric Dermatology | 2018

Successful Management of a Pancreatic Pseudocyst by Endoscopic Drainage

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


Pediatric Dermatology | 2018

A Patient with a 10-mm Solid Pseudopapillary Neoplasm of the Pancreas in whom Contrast-enhanced Endoscopic Ultrasonography was Useful for Diagnosis

Masafumi Watanabe; Kosuke Okuwaki; Mitsuhiro Kida; Kai Adachi; Masayoshi Tadehara; Seigo Nakatani; Kazuho Uehara; Hironori Masutani; Yusuke Kawaguchi; Eiji Miyata; Rikiya Hasegawa; Toru Kaneko; Hiroshi Yamauchi; Tomohisa Iwai; Hiroshi Imaizumi; Wasaburo Koizumi


Pediatric Dermatology | 2018

Two Cases of Severe Acute Pancreatitis Following Duodenal Papillary Biopsy

Yu Ishibashi; Tomohisa Iwai; Eiji Miyata; Rikiya Hasegawa; Toru Kaneko; Koji Yamauchi; Kosuke Okuwaki; Hiroshi Imaizumi; Mitsuhiro Kida; Wasaburo Koizumi

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