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Masahiro Endo

Publications and source records attributed to Masahiro Endo.

At least 55 records · Page 3Linked to original sources
PubMed2005

Clinical potentials for dynamic contrast-enhanced hepatic volumetric cine imaging with the prototype 256-MDCT scanner.

OBJECTIVE: To achieve dynamic contrast-enhanced hepatic volumetric cine imaging, we developed a prototype 256-MDCT scanner. This study examined the feasibility of the technique for human hepatic imaging in three hepatocellular carcinoma patients. CONCLUSION: Volumetric cine imaging successfully visualized dynamic contrast enhancement of the hepatocellular carcinoma. It is helpful to evaluate the phase of contrast enhancement or for functional studies of the head, renal artery, coronary artery, and liver.

Aged↗
PubMed2005

Experimental evaluation of conversion factors, N(D,w)/N(X), for Roos-type and Advanced-Markus-type plane-parallel ionization chambers.

A Japanese code of practice for clinical dosimetry, titled "Standard Dosimetry of Absorbed Dose in External Beam Radiotherapy" was published by the Japan Society of Medical Physics (JSMP) in 2002. It mostly followed IAEA Technical Reports Series No. 398, which was based on N(D,w), i.e., the calibration factor in terms of absorbed dose to water for a dosimeter. The Japanese primary standard dosimetry laboratory, however, has not supplied N(D,w) but N(X), as the calibration factor in terms of exposure. The unique feature of the Japanese code was provision of a data table of calculated conversion factors, N(D,w) / N(X) values, for many types of ionization chambers, excluding new plane-parallel ionization chambers. This paper describes the experimental evaluation of the conversion factors for the new plane-parallel ionization chambers, such as the Roos-type and Advanced Markus chambers. The obtained N(D,w) / N(X) values for PTW 34001, Wellhöfer PPC 40 and PTW 34045 were 37.96 +/- 0.19, 37.85 +/- 0.36 and 37.90 +/- 0.26 (Gy/C kg(-1)), respectively. They agreed with estimations based on Monte Carlo calculations.

Calibration↗
PubMed2005

Weekly paclitaxel and carboplatin with concurrent radiation therapy in locally advanced non-small cell lung cancer: phase I study.

PURPOSE: The optimal dose of weekly paclitaxel in combination with carboplatin and concurrent radiation therapy (CRT) in patients with locally advanced non-small cell lung cancer (NSCLC) is not well defined in Japan. The purpose of this study was to define the maximum-tolerated dose (MTD) of paclitaxel in this combination. MATERIALS AND METHODS: Treatment consisted of weekly paclitaxel plus carboplatin fixed AUC 2 and CRT for a total 60 Gy at 2 Gy/fraction/day 5 times weekly for 6 weeks. The dose of paclitaxel was 25 mg/m2 in the first cohort and escalated by 5 mg/m2 per cohort. RESULTS AND CONCLUSION: A total of 18 patients were enrolled and analyzed. The dose limiting toxicity of this study was considered to be pulmonary toxicity, and the MTD of it was determined to be 45 mg/m2 of paclitaxel in patients with NSCLC. Further evaluation of this regimen in a phase II trial is underway.

Adult↗
PubMed2004

Clinical trial of fundoscopy under general anesthesia for pediatric outpatients with retinoblastoma.

Retinoblastoma brings suffering, particularly to children. Formerly management during fundoscopy for children in Japan saw children's movements restricted with a blanket held by their parents or by nurses. This situation was sad, and the performance of the fundoscopy was limited because the children were crying and moving during the examination. After we received letters from the families of such children, we decided to introduce day-care general anesthesia for fundoscopy. After we investigated the current status of the treatment of retinoblastoma in leading countries, we carried out a trial of day-care general anesthesia for fundoscopy in 70 pediatric patients with retinoblastoma. We have now finished this first trial of day-care anesthesia, and we expect that discharge from hospital to places a longer distance away will be feasible.

Anesthesia, General↗
PubMed2004

Picture archiving and communication system introduced to a new Japanese cancer center hospital.

Picture archiving and communication systems (PACS) have been widely introduced as a credible alternative to the traditional film-based radiological service. Shizuoka Cancer Center Hospital (SCCH) introduced PACS and hospital information systems as an alternative to the film- and traditional paper-based hospital system at the opening of the hospital. Using PACS, whole images and their reports can be available at any nearby terminal. Users can select the display format for monitor viewing on the bases of individual preference and navigate through cases by buttons and rollerballs on the mouse with easy handling and quick response. Most clinicians in SCCH evaluated such medical circumstances well. Filmless image management systems will become popular in all hospitals in the near feature. All staff in each hospital should investigate the merits and demerits of this system and how to introduce it effectively.

Cancer Care Facilities↗
PubMed2004

Physical performance evaluation of a 256-slice CT-scanner for four-dimensional imaging.

We have developed a prototype 256-slice CT-scanner for four-dimensional (4D) imaging that employs continuous rotations of a cone-beam. Since a cone-beam scan along a circular orbit does not collect a complete set of data to make an exact reconstruction of a volume [three-dimensional (3D) image], it might cause disadvantages or artifacts. To examine effects of the cone-beam data collection on image quality, we have evaluated physical performance of the prototype 256-slice CT-scanner with 0.5 mm slices and compared it to that of a 16-slice CT-scanner with 0.75 mm slices. As a result, we found that image noise, uniformity, and high contrast detectability were independent of z coordinate. A Feldkamp artifact was observed in distortion measurements. Full width at half maximum (FWHM) of slice sensitivity profiles (SSP) increased with z coordinate though it seemed to be caused by other reasons than incompleteness of data. With regard to low contrast detectability, smaller objects were detected more clearly at the midplane (z = 0 mm) than at z = 40 mm, though circular-band like artifacts affected detection. The comparison between the 16-slice and the 256-slice scanners showed better performance for the 16-slice scanner regarding the SSP, low contrast detectability, and distortion. The inferiorities of the 256-slice scanner in other than distortion measurement (Feldkamp artifact) seemed to be partly caused by the prototype nature of the scanner and should be improved in the future scanner. The image noise, uniformity, and high contrast detectability were almost identical for both CTs. The 256-slice scanner was superior to the 16-slice scanner regarding the PSF, though it was caused by the smaller transverse beam width of the 256-slice scanner. In order to compare both scanners comprehensively in terms of exposure dose, noise, slice thickness, and transverse spatial resolution, K=Dsigma2ha3 was calculated, where D was exposure dose (CT dose index), sigma was magnitude of noise, h was slice thickness (FWHM of SSP), and a was transverse spatial resolution (FWHM of PSF). The results showed that the K value was 25% larger for the 16-slice scanner, and that the 256-slice scanner was 1.25 times more effective than the 16-slice scanner at the midplane. The superiority in K value for the 256-slice scanner might be partly caused by decrease of wasted exposure with a wide-angle cone-beam scan. In spite of the several problems of the 256-slice scanner, it took a volume data approximately 1.0 mm (transverse) x 1.3 mm (longitudinal) resolution for a wide field of view (approximately 100 mm long) along the zeta axis in a 1 s scan if resolution was defined by the FWHM of the PSF or the SSP, which should be very useful to take dynamic 3D (4D) images of moving organs.

Biophysical Phenomena↗
PubMed2004

A new radiation shielding block material for radiation therapy.

In recent years, lead has been recognized as a source of environmental pollution; this includes lead use for radiation shielding in radiotherapy. We looked for a new material that could be a lead substitute. We chose a material composed of tungsten and resin. We compared the attenuation coefficient of the material with those of lead and Lipowitz's metal, and found the material has a higher attenuation coefficient than the other two. The material may be used as a substitute for lead because it is easy to fabricate and friendly to the environment.

Biocompatible Materials↗
PubMed2004

CT fluoroscopy-guided bronchoscopic dye marking for resection of small peripheral pulmonary nodules.

STUDY OBJECTIVE: To determine the diagnostic reliability and safety of a new marking technique using transbronchoscopic dye injection under CT fluoroscopy for preoperative localization of a small pulmonary nodule. DESIGN: Prospective study. SETTING: Hyogo Medical Center for Adults and Shizuoka Cancer Center in Japan. PATIENTS: Seventeen patients who had a peripheral pulmonary nodule < 15 mm in size on CT scans that was suspected to be difficult to localize by visual inspection and manual palpation at our institutes between April 2000 and October 2002. INTERVENTIONS: After a bronchoscope was inserted orally under local anesthesia and was introduced into the related bronchus of the target nodule, a Teflon sheath catheter with metal tip was inserted transbronchoscopically and was advanced into the visceral pleura. By monitoring CT fluoroscopy, the catheter tip was positioned at the nearest pleural surface of the nodule, and 0.5 mL indigo carmine was injected under deep inspiratory breathhold. CT scans were obtained to confirm the relationship between the injected dye area and the nodule. MEASUREMENTS AND RESULTS: The dye injections were performed completely in all 17 patients, who subsequently underwent lung resection guided by the dye staining. There were no complications or harmful effects of the surgery. The area of injected dye was demonstrated as a hazy focal lesion about 10 mm beneath the pleura on the high-resolution CT scan, and was clearly visible as a patchy dark blue area about 20 mm in size on the visceral pleura at surgery. The mean distance between the nodule and the dye was 20 mm on the CT scan (distance range, 0 to 30 mm). The mean examination time with this technique was approximately 35 min (range, 25 to 45 min). The mean CT fluoroscopic time was 60 s (range, 30 to 120 s). CONCLUSIONS: Our transbronchial "tattooing" technique is safe and reliable. We think it is superior to previous marking methods.

Adult↗
PubMed2004

ERK activation and subsequent RB phosphorylation are important determinants of the sensitivity to paclitaxel in lung adenocarcinoma cells.

Paclitaxel is used frequently in the treatment of advanced non-small cell lung cancer. This study was carried out in order to determine the role of extracellular signal-regulated kinases (ERK) and retinoblastoma protein (pRB) in the governing mechanism resistance to paclitaxel using two lung adenocarcinoma cell lines with differing sensitivities. In paclitaxel-sensitive Ma-10 cells, treatment with paclitaxel induced pRB phosphorylation at Ser795 and ERK activation. In contrast, in paclitaxel-resistant Ma-31 cells, paclitaxel dephosphorylated pRB at Ser795 without affecting ERK activity. A specific ERK inhibitor, PD98059, blocked paclitaxel-induced ERK activation and pRB phosphorylation at Ser795 in Ma-10 cells. Furthermore, PD98059 inhibited cell cycle progression during paclitaxel treatment, the accumulation of sub-G1 population, and the cytotoxic effect by paclitaxel in Ma-10 cells, suggesting that ERK activation by paclitaxel, subsequent pRB phosphorylation, and the cell cycle progression during paclitaxel treatment are important determinants of sensitivity to paclitaxel. These observations raise the possibility that the promotion of cell cycle during the exposure of lung cancer cells to paclitaxel may sensitize resistant cells to paclitaxel.

Adenocarcinoma↗
PubMed2004

[Left ventricular free wall rupture].

BACKGROUND: Left ventricular (LV) free wall rupture is an uncommon but catastrophic event after acute myocardial infarction and is associated with a high mortality. Some patients may be salvaged with emergent operation. Padro et al. described a sutureless technique for the treatment of postinfarction LV free wall rupture. We have adopted a similar sutureless technique using a fibrin glue-oxycellulose fixation. METHODS: A review of 32 patients during a 20-year period who were referred to coronary care unit (CCU) with postinfarction LV free wall rupture was conducted. There were 17 men and 15 women with an average age of 68.8 years. Nine patients were treated who having one-stage operation of simultaneous 7 ventricular septal perforation and 2 coronary artery bypass grafting (CABG). Nine patients were sutured directly with a felt sandwich technique with or without cardiopulmonary bypass. Five patients were treated with pericardiectomy and pericardiocentesis using direct vision. Nine patients were sealed with sutureless method using fibrin glue-oxycellurose fixation without cardiopulmonary bypass. RESULTS: Eleven hospital deaths (34.4%, 11/32) were occurred in the all patints. However, 1 death (7.1%, 1/14) occurred in the pericardiectomy and in the sutureless sealed groups. CONCLUSIONS: A sutureless technique for an oozing type of postinfarction LV free wall rupture is effective.

Adult↗
PubMed2003

Orthogonal aperture multiplexing for multilayered waveguide holographic read-only memories.

A multilayered waveguide holographic read-only memory is a promising candidate for the next generation of optical data storage systems. We improved the data density of the memory by using a multiplexing method with a set of orthogonal optical masks. We multiplexed as many as nine images into one waveguide hologram, and all the observed images had negligible cross talk. This made it possible to achieve a ninefold increase in data density. We provide experimental results for both metallic and liquid-crystal masks.

Journal Article↗
PubMed2003

Bilateral versus unilateral internal mammary revascularization in patients with diabetes.

BACKGROUND: This historical cohort study evaluated the benefit of bilateral internal mammary artery (BIMA) grafts in coronary bypass grafting (CABG) for patients with diabetes. METHODS AND RESULTS: We performed elective, isolated, primary, multiple CABG using skeletonized internal mammary artery (IMA) grafts for multivessel disease in 1131 patients, 467 (41.3%) of whom had type 2 diabetes mellitus. The early and long-term results were compared between 277 patients with diabetes using single IMA (SIMA) grafts and 190 using BIMA grafts (median follow-up, 8.1 years). Hospital mortality was similar in both groups. Early patency rate of all grafts was significantly higher using BIMA than using SIMA (97.7% versus 93.8%, P=0.0012). Survival rates were not significantly different between SIMA and BIMA groups. Late cardiac mortality was significantly higher in patients with low ejection fraction (0.4 or lower) compared with preserved ejection fraction (higher than 0.4) (P=0.0001). In patients with preserved ejection fraction, 10-year survival rate was significantly higher using BIMA than using SIMA (87.8+/-3.5% versus 75.2+/-3.4%, P=0.04), and 10-year all death-free or repeat CABG or recurrent myocardial infarction-free rate was significantly higher using BIMA than using SIMA (86.6+/-3.6% versus 69.0+/-3.7%, P=0.0086). The hazard ratio for all death or repeated CABG or recurrent myocardial infarction in patients with preserved ejection fraction was markedly lower in the BIMA group (0.53; 95% CI, 0.31 to 0.9; P=0.019). CONCLUSIONS: Skeletonized BIMA grafts are beneficial in coronary revascularization for diabetic patients with preserved ejection fraction but have limited survival benefit for those with reduced ejection fraction attributable to high cardiac mortality.

Cohort Studies↗
PubMed2003

Estimating uncertainties of the geometrical range of particle radiotherapy during respiration.

PURPOSE: To propose a method for estimating uncertainties of the range calculation in particle radiotherapy associated with patient respiration. MATERIALS AND METHODS: A set of sequential CT images at every 0.2 s was reconstructed from continuous X-ray projection data accumulated by dynamic helical scanning. At the same time that CT data was acquired, the respiratory signal of the patient and the X-ray on/off signal on CT scanner were recorded. Each CT image was timed according to the phase of respiration waveform. Conversion of the CT number to the water equivalent path length (WEL) was performed with our treatment planning system that included a conversion table. As an illustration, the CT images of a patient with liver cancer at the right upper lobe were analyzed. The geometric size of the liver and WELs from body surface to isocenter were measured in each CT image. RESULTS: Variations of WEL from body surface to isocenter at the anterior-posterior and posterior-anterior direction were 6.2 mm and 18.9 mm, respectively. Liver size changed by 35.2 mm. However, these variations were shown to be considerably reduced by gated irradiation. CONCLUSIONS: A method using sequential CT images with respiration waveform was proposed. It appeared to be useful in evaluating the uncertainties of the range calculation associated with patient breathing.

Artifacts↗
PubMed2003

Electron density measurement with dual-energy x-ray CT using synchrotron radiation.

Monochromatic x-ray computed tomography (CT) at two different energies provides information about electron density of human tissue without ambiguity due to the beam hardening effect. This information makes the treatment planning for proton and heavy-ion radiotherapy more precise. We have started a feasibility study on dual energy x-ray CT by using synchrotron radiation. A translation-rotation scanning CT system was developed for quantitative measurement in order to clarify what precision in the measurement was achieved. Liquid samples of solutions of K2HPO4 and solid samples of tissue equivalent materials were used to simulate human tissue. The experiments were carried out using monochromatic x-rays with energies of 40, 70 and 80 keV produced by monochromatizing synchrotron radiation. The solid samples were also measured in a complementary method using high-energy carbon beams to evaluate the electron densities. The measured electron densities were compared with the theoretical values or the values measured in the complementary method. It was found that these values were in agreement in 0.9% on average. Effective atomic numbers were obtained as well from dual-energy x-ray CT. The tomographic image based on each of the electron densities and the effective atomic number presents a different feature of the material, and its contrast drastically differs from that in a conventional CT image.

Connective Tissue↗
PubMed2003

Predictive value of dose-volume histogram parameters for predicting radiation pneumonitis after concurrent chemoradiation for lung cancer.

PURPOSE: To clarify whether the percentage of pulmonary volume irradiated to >20 Gy (V20) is related to the incidence and grade of radiation pneumonitis (RP) in cases of lung cancer treated with concurrent chemoradiation. METHODS AND MATERIALS: The subjects comprised 71 patients with lung cancer who were treated with conventionally fractionated definitive concurrent chemoradiation. The chemotherapy agents were carboplatin or cisplatin combined with taxane for most patients. Radiotherapy was delivered at 1.8-2.0 Gy fractions once daily to a total of 48-66 Gy (median 60). We analyzed the relation between RP grade and V20. Univariate and multivariate analyses were performed to assess patient- and treatment-related factors, including age, gender, smoking history, pulmonary function (forced expiratory volume in 1 s), tumor location (upper lobe vs. middle/lower lobe), chemotherapy regimen (platinum + taxane vs. other), total dose, overall radiation periods in addition to V20. RESULTS: With a median follow-up of 7.5 months, an RP grade of 0, 1, 2, 3, and 5 was observed in 16, 35, 17, 1, and 2 patients, respectively; the corresponding mean V20 values were 20.1%, 22.0%, 26.3%, 27.0%, and 34.5%. The 6-month cumulative incidence of RP greater than Grade 2 was 8.7%, 18.3%, 51%, and 85% in patients with a V20 of or=31%, respectively (p <0.0001). According to both univariate and multivariate analyses, V20 was the only factor associated with RP of Grade 2 or greater. CONCLUSION: The incidence and grade of RP are significantly related to the V20 value. Thus, V20 appears to be a factor that can be used to predict RP after concurrent chemoradiation for lung cancer.

Adult↗
PubMed2003

Sequential bypass using the right gastroepiploic artery for coronary artery bypass grafting.

OBJECTIVE: Since 1989, we have applied the right gastroepiploic artery (RGEA) as a third arterial conduit for coronary artery bypass grafting (CABG) and started to use sequential RGEA in 1992. We evaluated the feasibility and efficacy of sequential RGEA grafting in CABG. METHODS: From December 1990 to January 2000, 46 patients underwent CABG with sequential RGEA. There were 42 male and 4 female patients with a mean age of 59 +/- 8.1 years. Mean postoperative follow-up period was 70 months. RESULTS: The mean number of anastomoses was 3.7 per patient. Mean luminal diameter of the RGEA was 2.2 +/- 0.4 mm by preoperative angiography and 2.3 +/- 0.6 mm by intraoperative measurement. Patency of the sequential RGEA was 92%; proximal anastomosis 100%, distal anastomosis 86% (p = 0.01). The 5-year actuarial survival and cardiac event-free rate were 91% and 93%, respectively. CONCLUSIONS: Sequential bypass using the RGEA is feasible, with excellent early and long-term results. The indication for sequential RGEA, however, needs careful anatomical consideration of both the luminal diameter of the RGEA and proximal stenosis of the target coronary arteries.

Adult↗
PubMed2003

Left ventricular mass index reduction early after an isolated aortic valve replacement with St. Jude Medical 19A-HP.

OBJECTIVES: It has been reported that the left ventricular mass index (LVMI) for the hypertrophic myocardium is reduced at an early stage following surgery. In this study, those factors affecting the changes in early postoperative LVMI were investigated in cases in which a St. Jude Medical 19A-HP (19HP) mechanical heart valve was used. METHODS: We studied 16 consecutive patients with pure aortic stenosis undergoing isolated aortic valve replacement using a 19HP between January 1994 and July 2001. The patients were all female, aged 64 +/- 6 years, with a body surface area of 1.44 +/- 0.10 m2 and preoperative New York Heart Association (NYHA) classification of 2.2 +/- 0.5. All patients underwent transthoracic echocardiography at 4.2 +/- 3.3 days before and 16.3 +/- 10.2 days after operation, and cardiac catheterization within a mean period of one month before operation. The correlations between the decrease of LVMI at 16.3 +/- 10.2 days after operation and perioperative parameters were determined. RESULTS: There was significant LVMI regression postoperatively (15 +/- 12%, p = 0.01), and only a significant negative correlation between the decrease of LVMI and preoperative left ventricular pressure (LVp) [r = -0.74, p < 0.01]. There was no effective LVMI reduction in the high preoperative LVp group (> or = 210 mmHg). CONCLUSION: It is expected that in the high LVp group, huge wall stress was being applied to the left ventricular muscle immediately before surgery and in the early period after surgery. Preoperative LVp is an important index for determining the surgical timing and safe perioperative management. We recommend early surgical treatment before LVp becomes more than 210 mmHg.

Aged↗