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Dive into the research topics where Masayuki Gyoten is active.

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Featured researches published by Masayuki Gyoten.


Acta Oto-laryngologica | 2008

Superselective angiographic embolization for intractable epistaxis

Kenji Fukutsuji; Suetaka Nishiike; Teruhito Aihara; Masako Uno; Tamotsu Harada; Masayuki Gyoten; Shigeki Imai

Conclusions. Routine embolization of the ipsilateral facial artery (FA) is effective because of the high success rate. The use of different embolic materials for the internal maxillary artery (IMA) and the FA was considered safe because of the absence of major complications. Objective. To evaluate outcomes of routine embolization of the FA as well as the IMA ipsilateral to the bleeding site for intractable epistaxis, and outcomes using different embolic materials for the FA and the IMA. Patients and methods. Twenty-two patients with intractable epistaxis who underwent superselective embolization were retrospectively analyzed with a mean follow-up of 7 months. The FA and the IMA ipsilateral to the bleeding site were embolized. Two embolic materials, gelatin sponge and microcoils, were used for the IMA and the FA, respectively. Results. The short-term success rate within the first 7 days was 77.3% (17/22). The long-term success rate was 95.5% (21/22). There were no major complications in 22 cases. Minor complications occurred in 13 cases (59%). These minor complications usually did not last more than a week and most resolved within a day.


European Radiology | 2004

T2-weighted MR imaging of prostate cancer: multishot echo-planar imaging vs fast spin-echo imaging

Tsutomu Tamada; Teruki Sone; Kiyohisa Nagai; Yoshimasa Jo; Masayuki Gyoten; Shigeki Imai; Yasumasa Kajihara; Masao Fukunaga

The aim of the present study was to assess the performance of pre-biopsy T2-weighted MR imaging using multishot echo-planar imaging (EPI) sequence for visualization of prostate cancer and to compare image quality with that of fast spin-echo (FSE) sequence. Thirty-nine patients with suspected prostate cancer and one healthy male volunteer were examined on a 1.5-T MR scanner equipped with a pelvic phased-array coil. Axial MR images were obtained using multishot EPI sequence with a multishot number of 16 and FSE sequence without fat suppression. Paired EPI and FSE images were independently evaluated by three radiologists. Furthermore, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between EPI and FSE images of 12 pathologically proven lesions of prostate cancer. Delineation of the periprostatic venous plexus, prostate zonal anatomy, and seminal vesicle on EPI was graded to be superior/inferior to FSE in 15.8/0, 14.6/0, and 21.5/4.3% of cases, respectively. On the other hand, delineation of the neurovascular bundle was superior/inferior to FSE in 2.6/13.2% of cases. The SNR and CNR of prostate cancer on EPI were significantly higher than those on FSE (7.99±2.51 vs 3.36±0.58, p<0.0001, and 5.51±2.02 vs 2.21±0.79, p<0.0001, respectively). In conclusion, multishot EPI has higher quality of contrast resolution for imaging of prostate cancer compared with FSE and would have the potential usefulness in the detection of prostate cancer, although these results obtained with a phased-array coil cannot be extrapolated to examinations performed with an endorectal coil.


Catheterization and Cardiovascular Interventions | 2007

Transradial approach for noncoronary angiography and interventions.

Takenori Yamashita; Shigeki Imai; Tsutomu Tamada; Akira Yamamoto; Naoto Egashira; Shigeru Watanabe; Hiroki Higashi; Masayuki Gyoten

Purpose: The purpose of this study was to retrospectively evaluate the feasibility and safety of a transradial approach for non‐coronary angiography and interventions. Background: Generally, the transradial approach is used for coronary angiography and intervention around the world, and experiences have been widely reported. However, few large studies have examined the transradial approach for vessels other than the coronary or cerebral artery. Methods: Subjects comprised 329 patients who underwent a total of 400 procedures (285 abdomens, 68 pelvises, and 47 lower limbs) with transradial angiography and interventions between January 1999 and June 2006. Normal Allen test results were confirmed before all procedures. A 130‐ or 150‐cm long 4F catheter modified to our own design was used for angiography and interventions such as transarterial embolization or transarterial chemotherapy. Results: Radial artery access was unachievable in 19 of the 400 procedures (4.8%). The radial artery was injured during 1 procedure (0.2%). In the remaining 380 procedures, sufficient angiography was obtained to grasp the condition of indispensable vessels for diagnosis and interventions scheduled in advance succeeded. Total transradial technical success rate in the series was 95%. Frequency of complications such as radial injury or radial spasm was 1.8%. No cases of local hematoma, hand ischemia, or cerebral infarction were encountered. Conclusion: The transradial approach was useful for non‐coronary angiography and interventions and offers the advantages of low risk and reduced stress on patients.


Neuroradiology | 1997

MRI in carcinomatous encephalitis

Hiroshi Shirai; Shigeki Imai; Yasumasa Kajihara; Tsutomu Tamada; Masayuki Gyoten; Tsuyoshi Kamei; Tsuyoshi Hata; T. Shirabe

Abstract We report a rare case of miliary brain metastases presenting with symptoms similar to encephalitis (“carcinomatous encephalitis”). Contrast-enhanced MRI demonstrated miliary metastases more distinctly than other imaging methods and reproduced the pathological features.


International Journal of Clinical Oncology | 2002

A long-term survivor of leiomyosarcoma around the right side of the base of the skull: effective radiotherapy combined with intra-arterial chemotherapy.

Ryoji Tokiya; Yoshinari Imajo; Eisaku Yoden; Junichi Hiratsuka; Makito Kobatake; Masayuki Gyoten; Shigeki Imai; Yasumasa Kajihara

Abstract We report a rare case of a leiomyosarcoma that developed around the right side of the base of the skull in a 51-year-old woman. The patient consulted our hospital complaining of pain in the right side of her neck and upper right arm in August 1994. A leiomyosarcoma, originating around the right side of the neck and base of the skull was diagnosed. Initially, surgery was planned, but invasion into the spinal canal was discovered. Curative resection of the leiomyosarcoma around the right side of the base of the skull was not possible. Therefore, external beam radiotherapy (EBRT) combined with intra-arterial chemotherapy and hyperthermia was employed. After the treatment, the tumor decreased in size to 45% of its initial volume, and, simultaneously, her symptoms completely disappeared. The patient initially remained clinically free of the disease, but showed reaggravations at the primary tumor site 3 years and 3 months, and 4 years and 11 months, after the first treatment. The reaggravations were treated with EBRT combined with intra-arterial chemotherapy. As a result, she survived for 5 years and 7 months after the first treatment.


International Journal of Clinical Oncology | 1998

Arterial embolization for control of bleeding in advanced head and neck malignancy

Shigeki Imai; Yasumasa Kajihara; Tsuyoshi Kamei; Kuwako Komaki; Tsutomu Tamada; Hiroshi Shirai; Masayuki Gyoten; Toru Handa; Takeshi Akisada; Yozo Orita

BackgroundThis study was undertaken to assess the efficacy and suitability of an arterial embolization technique for the control of bleeding in advanced head and neck malignancies.MethodsEmbolization was performed on 6 patients with advanced head and neck malignancy using various embolic materials for the control of bleeding. The primary tumors were located in the nasopharynx, hypopharynx (n=2), oral base, face, and external auditory canal. All of these patients had severe anemia and 5 had massive regional hemorrhages.All bleeding was well controlled by the arterial embolization; 2 patients were cured of hypovolemic shock. None of the patients died as a direct result of tumor bleeding, and there were no massive rebleeding cases in our series.ConclusionArterial embolization offers an effective, safe, and fast method for controlling bleeding from advanced head and neck malignancies. A good working relationship between the surgeon and the interventional radiologist provides the greatest chance for sucess in such cases.


Radiation Medicine | 2004

Iatrogenic venous air embolism caused by CT injector--from a risk management point of view.

Shigeki Imai; Tsutomu Tamada; Masayuki Gyoten; Takenori Yamashita; Yasumasa Kajihara


Radiation Medicine | 2000

Superselective embolization for bleeding from duodenal diverticulum: a case report.

Shigeki Imai; Yasumasa Kajihara; Hiroshi Shirai; Tsutomu Tamada; Masayuki Gyoten; Atsuhiro Fukuda; Chiiho Fujii


Toukeibu Gan | 2008

Superselective intra-arterial chemoradiotherapy for advanced head and neck cancers: evaluation of preservation of organ function

Takeshi Akisada; Tamotsu Harada; Shigeki Imai; Masayuki Gyoten; Takashi Hiraoka


頭頸部癌/ 日本頭頸部癌学会 | 2007

Superselective intra-arterial chemo-radiotherapy for advanced hypopharyngeal carcinoma

Masako Uno; Takeshi Akisada; Teruhito Aihara; Suetaka Nishiike; Norimasa Morita; Tamotsu Harada; Masayuki Gyoten; Shigeki Imai

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Shigeki Imai

Kawasaki Medical School

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