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Featured researches published by Koji Masui.


Brachytherapy | 2015

Preliminary results of MRI-assisted high-dose-rate interstitial brachytherapy for uterine cervical cancer

Ken Yoshida; Hideya Yamazaki; Tadashi Takenaka; Tadayuki Kotsuma; Shunsuke Miyake; Mari Ueda; Mineo Yoshida; Koji Masui; Yasuo Yoshioka; Yasuo Uesugi; T. Shimbo; Nobuhiko Yoshikawa; Hiroto Yoshioka; Kazumasa Aramoto; Yoshifumi Narumi; Shigetoshi Yamada; Keiji Tatsumi; Eiichi Tanaka

PURPOSE To investigate the effectiveness of our novel MRI-assisted high-dose-rate interstitial brachytherapy for uterine cervical cancer. METHODS AND MATERIALS Between June 2005 and June 2009, 29 previously untreated patients with cervical cancer were enrolled (2 T2b, 2 T3a, 19 T3b, and 6 T4 tumors). We implanted MRI-compatible plastic catheters using our unique ambulatory technique. The total treatment doses were 30-36 Gy (6 Gy per fraction) combined with external beam radiotherapy. RESULTS The median D90 (high-risk clinical target volume), D(2 cc) (bladder), and D(2 cc) (rectum) per fraction were 6.9, 5, and 4.6 Gy, respectively. The 3-year local control rates were 100%, 95%, and 83% for T2, T3, and T4 tumors, respectively. Grade 3 or 4 late complications occurred in 4 patients. CONCLUSIONS Our preliminary evaluation of image-based high-dose-rate interstitial brachytherapy showed favorable local treatment results with an acceptable complication rate.


Journal of Vascular and Interventional Radiology | 2013

Transcatheter Arterial Embolization with N-Butyl Cyanoacrylate for Acute Life-threatening Gastroduodenal Bleeding Uncontrolled by Endoscopic Hemostasis

Hiroyuki Morishita; Takuji Yamagami; Tomohiro Matsumoto; Shunsuke Asai; Koji Masui; Hideki Sato; Atsushi Majima; Osamu Sato

PURPOSE To investigate the feasibility, efficacy, and safety of transcatheter arterial embolization with N-butyl cyanoacrylate (NBCA) for gastroduodenal nonvariceal bleeding uncontrolled by endoscopic hemostasis. MATERIALS AND METHODS Between January 2006 and December 2011, a total of 317 patients underwent emergent endoscopic therapy for nonvariceal gastroduodenal bleeding, but hemostasis was not achieved in 20 cases. Emergent surgery was performed immediately following endoscopy in two patients. Arteriography was performed in the remaining 18 patients, and embolization with NBCA was performed in 15 patients (mean age, 71.3 y) in whom the bleeding site was detected on arteriography. For embolization, NBCA was mixed with iodized oil at a ratio of 1:1.5-1:4, and no other embolic material was used in the procedure. Technical and clinical success rates, recurrent bleeding, procedural time, complications, and clinical outcomes were determined for each procedure. RESULTS Embolization with NBCA was technically and clinically successful in all procedures, without major complications. No patient receiving embolization with NBCA experienced recurrent bleeding or required further treatment after the one-session procedure. All patients were discharged after clinical improvement. The time between puncture of the femoral artery and completion of embolization ranged from 25 to 240 minutes (mean, 66 min), and the time between the microcatheter reaching the ultimate catheter location selected for embolization and hemostasis ranged from 142 to 550 seconds (mean, 322s). CONCLUSIONS In this limited series, embolization with NBCA was found to be a safe, feasible, and effective treatment for gastroduodenal arterial bleeding when endoscopic hemostasis had failed.


Acta Radiologica | 2012

CT-guided percutaneous drainage within intervertebral space for pyogenic spondylodiscitis with psoas abscess.

Tomohiro Matsumoto; Takuji Yamagami; Hiroyuki Morishita; Shigeharu Iida; Shunsuke Asai; Koji Masui; Shoichi Yamazoe; Osamu Sato; Tsunehiko Nishimura

Background Reports on CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis with a secondary psoas abscess are limited. Purpose To evaluate CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis and a secondary psoas abscess in which the two sites appear to communicate. Material and Methods Eight patients with pyogenic spondylodiscitis and a secondary psoas abscess showing communication with the intradiscal abscess underwent CT-guided percutaneous drainage within the intervertebral space. The clinical outcome was retrospectively assessed. Results An 8-French pigtail catheter within the intervertebral space was successfully placed in all patients. Seven patients responded well to this treatment. The one remaining patient who had developed septic shock before the procedure died on the following day. The mean duration of drainage was 32 days (13–70 days). Only one patient with persistent back pain underwent surgery for stabilization of the spine after the improvement of inflammation. Among seven patients responding well, long-term follow-up (91–801 days, mean 292 days) was conducted in six patients excluding one patient who died of asphyxiation due to aspiration unrelated to the procedure within 30 days after the procedure. In these six patients, no recurrence of either pyogenic spondylodiscitis or the psoas abscess was noted. Conclusion CT-guided percutaneous drainage within the intervertebral space can be effective for patients with pyogenic spondylodiscitis and a secondary psoas abscess if the psoas abscess communicates with the intradiscal abscess.


Journal of Contemporary Brachytherapy | 2014

High-dose-rate interstitial brachytherapy for mobile tongue cancer: preliminary results of a dose reduction trial.

Hironori Akiyama; Ken Yoshida; Hideya Yamazaki; Tadashi Takenaka; Tadayuki Kotsuma; Koji Masui; Yasuo Yoshioka; Takumi Arika; Kimishige Shimizutani; Eiichi Tanaka

Purpose To compare the outcome of our facility with another about the shortened schedule (60 Gy in 10 fractions to 54 Gy in 9 fractions) of high-dose-rate interstitial brachytherapy (HDR ISBT) for mobile tongue cancer. Material and methods Eighteen patients were treated with HDR ISBT as a monotherapy in dose reduction schedule with some unique technique to determine the border of tumor accuracy (lugols staining and metal marker), and to minimize adverse effect (lead-lined silicon block) at our facility. Results The 2-year local and regional control rates and cause-specific survival rate were 82%, 80%, and 83% and moderate to severe late complications occurred in five patients (28%), which were almost the same treatment results achieved by another facility. Conclusions We recommend 54 Gy in 9 fractions over 7 days as a feasible treatment to reduce patient discomfort in mobile tongue cancer patients.


CardioVascular and Interventional Radiology | 2012

A New Flow Control Technique Using Diluted Epinephrine in the N-butyl-2-cyanoacrylate Embolization of Visceral Artery Pseudoaneurysms Secondary to Chronic Pancreatitis

Hiroyuki Morishita; Takuji Yamagami; Yoshito Takeuchi; Tomohiro Matsumoto; Shunsuke Asai; Koji Masui; Hideki Sato; Fumihiro Taniguchi; Osamu Sato; Tsunehiko Nishimura

Although n-butyl-2-cyanoacrylate (NBCA) has been used as an effective liquid embolization material, its indication for pseudoaneurysms has seemingly been limited because of the technical difficulties of using NBCA, such as reflux to the parent artery and causing significant infarction. Thus, considerable skill in using NBCA or a device to control blood flow during its polymerization is required to achieve embolization without severe complications. We report our new technique for controlling blood flow using diluted epinephrine in transcatheter arterial NBCA embolization of five pseudoaneurysms in four cases secondary to hemosuccus pancreaticus.


Asian Journal of Andrology | 2015

Salvage brachytherapy for locally recurrent prostate cancer after external beam radiotherapy

Yasuhiro Yamada; Koji Okihara; Tsuyoshi Iwata; Koji Masui; Kazumi Kamoi; Kei Yamada; Tsuneharu Miki

External beam radiotherapy (EBRT) is a standard treatment for prostate cancer. Despite the development of novel radiotherapy techniques such as intensity-modulated conformal radiotherapy, the risk of local recurrence after EBRT has not been obviated. Various local treatment options (including salvage prostatectomy, brachytherapy, cryotherapy, and high-intensity focused ultrasound [HIFU]) have been employed in cases of local recurrence after primary EBRT. Brachytherapy is the first-line treatment for low-risk and selected intermediate-risk prostate tumors. However, few studies have examined the use of brachytherapy to treat post-EBRT recurrent prostate cancer. The purpose of this paper is to analyze the current state of our knowledge about the effects of salvage brachytherapy in patients who develop locally recurrent prostate cancer after primary EBRT. This article also introduces our novel permanent brachytherapy salvage method.


Brachytherapy | 2015

Treatment results of image-guided high-dose-rate interstitial brachytherapy for pelvic recurrence of uterine cancer

Ken Yoshida; Hideya Yamazaki; Tadayuki Kotsuma; Tadashi Takenaka; Koji Masui; Yasuo Yoshioka; Yasuo Uesugi; T. Shimbo; Nobuhiko Yoshikawa; Hiroto Yoshioka; Yoshifumi Narumi; Keiji Tatsumi; Eiichi Tanaka

PURPOSE We analyzed clinical data to evaluate the effectiveness of image-guided high-dose-rate interstitial brachytherapy (HDR-ISBT) for pelvic recurrence of uterine cancer. METHODS AND MATERIALS Between 2003 and 2011, 56 patients were treated with HDR-ISBT with or without external beam radiotherapy (EBRT). The median followup time was 33 months (range, 1-109 months). Pre-ISBT treatments included radical hysterectomy for 35 patients (Group A), radical hysterectomy with postoperative radiotherapy for 8 patients (Group B), and radical radiotherapy for 13 patients (Group C). We initiated MRI-assisted CT-based planning for the last 49 patients. The median ISBT single fraction dose was 6 Gy. The median total doses were 30 and 54 Gy with and without EBRT (range, 30-50 Gy) for Group A, respectively and 48 Gy without EBRT for Groups B and C. RESULTS The 3-year local control (LC) rates were 85%, 75%, and 46% for Groups A, B, and C, respectively (p = 0.017). The 3-year LC rates were 84%, 73%, and 33% for clinical target volume at the time of HDR-ISBT of <10, 10-29, and ≥30 cc, respectively (p = 0.005). The 3-year LC results tended to be higher for patients whose D100 (clinical target volume) was equal or higher than 67.1 Gy (p = 0.098). A total of 13 late complications of Grades 3-5 occurred in 11 patients (20%). CONCLUSIONS Our image-guided HDR-ISBT for pelvic recurrence of uterine cancer provided good treatment outcomes. The treatment results for patients who underwent radical surgery with or without postoperative radiotherapy are better than those for patients who underwent radical radiotherapy.


Journal of Gynecologic Oncology | 2015

Role of vaginal pallor reaction in predicting late vaginal stenosis after high-dose-rate brachytherapy in treatment-naive patients with cervical cancer

Ken Yoshida; Hideya Yamazaki; Satoaki Nakamura; Koji Masui; Tadayuki Kotsuma; Hironori Akiyama; Eiichi Tanaka; Nobuhiko Yoshikawa; Yasuo Uesugi; T. Shimbo; Yoshifumi Narumi; Yasuo Yoshioka

Objective To assess actual rates of late vaginal stenosis and identify predisposing factors for complications among patients with previously untreated cervical cancer following high-dose-rate brachytherapy. Methods We performed longitudinal analyses of 57 patients using the modified Dische score at 6, 12, 18, 24, 36, and 60 months after treatment, which consisted of 15 interstitial brachytherapys and 42 conventional intracavitary brachytherapys, with a median follow-up time of 36 months (range, 6 to 144 months). Results More than half of the patients developed grade 1 (mild) vaginal stenosis within the first year of follow-up, and grade 2 (97.5%, moderate) to grade 3 (severe) stenosis gradually increased with time. Actual stenosis rates for grade 1, 2, and 3 were 97.5% (95% confidence interval [CI], 92.7 to 97.5), 60.7% (95% CI, 42.2 to 79.3), and 7.4% (95% CI, 0 to 18.4) at 3 years after treatment. Pallor reaction grade 2-3 at 6 months was only a statistically significant predisposing factor for grade 2-3 late vaginal stenosis 3 years or later with a hazard ratio of 3.48 (95% CI, 1.32 to 9.19; p=0.018) by a multivariate Cox proportional hazard model. Patients with grade 0-1 pallor reaction at 6 months showed a grade ≥2 vaginal stenosis rate of 53%, whereas the grade 2-3 pallor reaction group achieved a grade ≥2 vaginal stenosis rate at 3 years at 100% (p=0.001). Conclusion High-dose-rate brachytherapy was associated with high incidence of late vaginal stenosis. Pallor reaction grade 2-3 at 6 months was predictive of late grade 2-3 vaginal stenosis at 3 years after treatment. These findings should prove helpful for patient counseling and preventive intervention.


Journal of Radiation Research | 2014

Three-dimensional image-based high-dose-rate interstitial brachytherapy for mobile tongue cancer

Ken Yoshida; Tadashi Takenaka; Hironori Akiyama; Hideya Yamazaki; Mineo Yoshida; Koji Masui; Tadayuki Kotsuma; Sungjae Baek; Yasuo Uesugi; T. Shimbo; Nobuhiko Yoshikawa; Takumi Arika; Yukihiro Koretsune; Yasuo Yoshioka; Yoshifumi Narumi; Eiichi Tanaka

To investigate the influence of a 3D image-based treatment-planning method for high-dose-rate interstitial brachytherapy (HDR-ISBT) for mobile tongue cancer, we analyzed dose–volume histogram results for the clinical target volume (CTV) and the mandible. Between October 2010 and November 2011, one and four patients having T2 and T3 tumors, respectively, were treated with HDR-ISBT. Multiplane implantation using 9–15 treatment applicators was performed. Lugols iodine staining, metal markers, ultrasonography, and magnetic resonance imaging were used to identify the contours of the gross tumor volume (defined as the CTV). The results of the image-based treatment plan were compared with those of the conventional simulated plan on the basis of a reference point 5 mm from the applicator position. The mean D90(CTV) and V100(CTV) were 112% of the prescribed dose (PD) and 98.1%PD, respectively, for the image-based plan, and 113%PD and 97.2%PD, respectively, for the conventional plan. The median CTVref/Vref was 0.23 for the image-based plan and 0.16 for the conventional plan (P = 0.01). The mean D0.1 cm3 (mandible), D1 cm3 (mandible), and D2 cm3 (mandible) were 80.1%PD, 62.5%PD, and 55.7%PD, respectively, for the image-based plan, and 109.1%PD (P = 0.02), 82.4%PD (P = 0.005), and 74%PD (P = 0.004), respectively, for the conventional plan). Image-based treatment planning may achieve high-conformity radiotherapy for the CTV and decrease irradiated doses to the mandible.


Radiotherapy and Oncology | 2018

Comparison of three moderate fractionated schedules employed in high-dose-rate brachytherapy monotherapy for clinically localized prostate cancer

Hideya Yamazaki; Koji Masui; Gen Suzuki; Satoaki Nakamura; Ken Yoshida; Tadayuki Kotsuma; Eiichi Tanaka; Keisuke Otani; Yasuo Yoshioka; Kazuhiko Ogawa

BACKGROUND Herein, we report the outcomes of 3 schedules of high-dose-rate interstitial brachytherapy (HDR-BT) monotherapy for localized prostate cancer. PATIENTS AND METHODS A total of 347 patients were treated with 45.5 Gy/7 fractions (n = 86; 45.5 Gy arm, median follow-up time 131 months), 49 Gy/7 fractions (n = 149; 49 Gy arm, 75.9 months), and 54 Gy/9 fractions (n = 112; 54 Gy arm, 68 months). RESULTS The actuarial 5-year biochemical failure-free survival rates were 86.8%, 94.1%, and 88.5% (p = 0.2023) for the 45.5 Gy, 49 Gy, and 54 Gy arms in the high-risk group; 90.4%, 100%, and 97.4% (p = 0.0818) in the intermediate-risk group; and not available, 100%, and 100% in the low-risk group, respectively. The 5-year distant metastasis-free (and overall) survival rates were 94.4%, 98.2%, and 96.3% (100%, 92.8%, and 99.1%) for the 45.5 Gy, 49 Gy, and 54 Gy arms (p = 0.5454 and p = 0.0028), respectively. At 5 years, accumulated incidence of grade ≥2 gastrointestinal toxicity was 1.2%, 2.7%, and 3.4% for the 45.5 Gy, 49 Gy, and 54 Gy arms (p = 0.5605), respectively. For genitourinary toxicity, the 49 Gy arm showed a higher grade ≥2 toxicity of 20.5% than those observed in the 45.5 Gy (2.4%) and 54 Gy arms (10.1%). No grade 4 or 5 of either type of toxicity was detected. CONCLUSIONS The 3 schedules showed equivocal outcomes in each risk group, with different toxicity profiles. HDR-BT monotherapy with these schedules is an acceptable treatment option for localized prostate cancer.

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Hideya Yamazaki

Kyoto Prefectural University of Medicine

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Tadashi Takenaka

Kyoto Prefectural University of Medicine

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Kei Yamada

Kyoto Prefectural University of Medicine

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Gen Suzuki

Kyoto Prefectural University of Medicine

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Satoaki Nakamura

Kyoto Prefectural University of Medicine

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T. Shimbo

Osaka Medical College

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