Masayuki Suzuki

Keio University, Tokyo, Tokyo-to, Japan

Are you Masayuki Suzuki?

Claim your profile

Publications (112)188.77 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: In Japan, the eradication rate of first-line therapy for Helicobacter pylori (H. pylori) with a proton pump inhibitor (PPI), amoxicillin (AMPC) and clarithromycin (CAM) has been decreasing because of a high prevalence of CAM resistance. A possible decrease of the eradication rate for second-line therapy with a PPI, AMPC and metronidazole (MNZ) is of concern. The aim of this study is to assess the trends in second-line eradication therapy for H. pylori in Japan. MATERIALS AND METHODS: We accumulated data retrospectively on patients administered second-line eradication therapy for Helicobacter pylori with a PPI, AMPC, and MNZ for 1 week after failure of first-line eradication therapy with a PPI, AMPC and CAM at 15 facilities in the Tokyo metropolitan area in Japan from 2007 to 2011. Trends for second-line eradication rates in modified intention-to-treat (ITT) analyses were investigated. Second-line eradication rates were categorized by three PPIs (rabeprazole (RPZ), lansoprazole (LPZ) or omeprazole (OMZ)) and evaluated. RESULTS: We accumulated data on 1373 patients. The overall second-line eradication rate was 92.4%. Second-line eradication rates in 2007, 2008, 2009, 2010 and 2011 were 97.7, 90.6, 94.5, 91.8 and 91.8%, respectively, with no significant trends revealed. Second-line eradication rates categorized by three PPIs for the entire 5-year period were 91.6, 93.4 and 92.4% (RPZ, LPZ and OPZ, respectively) with no significant differences among the three PPIs. CONCLUSIONS: From 2007 to 2011, there were no significant trends in the second-line eradication rates and the rates remained consistently high. From the viewpoint of high prevalence of CAM resistance in Japan, triple therapy with PPI, AMPC and MNZ may be a better strategy for first-line therapy compared to triple therapy with PPI, AMPC and CAM.
    Helicobacter 06/2013; · 3.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND AND AIM: The interval between first-line Helicobacter pylori eradication treatment and second-line treatment may be critical to the second-line therapeutic effect. We attempted to assess the association between the second-line eradication rates and the treatment interval. METHODS: Data of patients, who were administered the second-line H. pylori eradication regimen at Tokyo Medical Center between 2008 and 2012, were reviewed. RESULTS: Of the 148 patients enrolled, 1 patient dropped out. The eradication rates were 88.6% (ITT) and 89.3% (PP) for early eradication group (eradication interval < 180 days, patients number 132) and 68.8% (ITT and PP) for delayed eradication group (eradication interval ≧180 days, patients number 16). The eradication rate in the delayed eradication group was significantly lower than in the early eradication group (p=0.027 (ITT) and 0.021 (PP)). The eradication interval in the subjects showing eradication failure (124.0 ± 96.8 days, patients number 19) was significantly longer than those showing successful eradication (85.8 ± 56.9 days, patients number 128, p=0.008). CONCLUSION: Our results suggest that the delay of second-line treatment should be avoided.
    Journal of Gastroenterology and Hepatology 05/2013; · 3.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: INTRODUCTION: We investigated the patency rate of a biliary stent and the effects of ursodeoxycholic acid (UDCA) therapy and endoscopic sphincterotomy (EST) for difficult-to-remove common bile duct (CBD) stones. METHOD: A total of 63 endoscopic retrograde cholangiopancreatographies (ERCPs) were performed in 36 patients (mean age, 86.0 years; male-female, 17:19) for stenting. Among the 63 subjects, 28 were further treated with EST; 20, with UDCA therapy; and 43, with a stent only. RESULTS: The mean patency time was significantly longer in the UDCA treatment group (1012 days) than in the "stent only" group (354 days; p = 0.0002; hazard ratio, 0.253). The mean patency time was significantly longer in the patients who had stent placement with EST (1074 days) than in those who had stent placement without EST (279 days; p = 0.001; hazard ratio, 0.439). The mean patency time was significantly longer in the patients who had stent placement with UDCA therapy and EST (1211 days) than in the patients who had stent placement with either UDCA therapy or EST (425 days; p = 0.031; hazard ratio, 0.3292). The mean patency time was significantly longer in the patients who had stent placement with either UDCA therapy or EST than in those who had stent placement without UDCA therapy or EST (263 days; p = 0.0465; hazard ratio, 0.5124). CONCLUSION: Biliary stenting combined with UDCA therapy and EST may be considered as an effective treatment method for cases of CBD stones in elderly patients that are difficult to remove.
    Journal of Gastroenterology and Hepatology 10/2012; · 3.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to compare the efficacy and tolerability of the first-line Helicobacter pylori (H. pylori) eradication regimen composed of proton pump inhibitor, clarithromycin, and amoxicillin, with those of a regimen composed of proton pump inhibitor, metronidazole, and amoxicillin. Data of patients, who were administered the first-line H. pylori eradication regimen at Tokyo Medical Center between 2008 and 2011, were reviewed. All patients had H. pylori gastritis without peptic ulcer disease. The 7-day triple regimen composed of lansoprazole, clarithromycin, and amoxicillin was administered to 55 patients, and that composed of omeprazole, metronidazole, and amoxicillin was administered to 55 patients. Intention-to-treat and per-protocol eradication rates were 74.5 and 80.4%, respectively, for the regimen of lansoprazole, clarithromycin, and amoxicillin, whereas the corresponding rates were 96.4 and 100%, respectively, for the regimen of omeprazole, metronidazole, and amoxicillin. In conclusion, first-line H. pylori eradication therapy composed of omeprazole, metronidazole, and amoxicillin was significantly more effective than that composed of lansoprazole, clarithromycin, and amoxicillin, without differences in tolerability.
    Journal of Clinical Biochemistry and Nutrition 09/2012; 51(2):114-6. · 2.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Misregistration errors occur at the periphery of the hepatic region due to respiratory- and interval-related changes in hepatic shape. To reduce these misregistration errors, we developed a temporal and dynamic subtraction technique to enhance small hepatocellular carcinoma (HCC) by using a 3D nonlinear image-warping technique. The study population consisted of 21 patients with HCC. We registered the present and previous arterial-phase CT images or the present nonenhanced and arterial-phase CT images obtained in the same position by 3D global-matching plus 3D nonlinear image-warping. Temporal subtraction images were obtained by subtraction of the previous arterial-phase CT image from the warped present arterial-phase CT image. Dynamic subtraction images were obtained by subtraction of the present nonenhanced CT image from the warped present arterial-phase CT image. When we used this new technique, the number of good or excellent cases increased from 14.2% (3/21 cases) to 71.4% (15/21 cases) on temporal subtraction images. With this technique, subjective rating scores for image quality improved in 57.1% of cases (12/21 cases) on temporal subtraction images and 81.0% of cases (17/21 cases) on dynamic subtraction images. The results indicated that the new subtraction images were greatly improved by use of the 3D nonlinear image-warping technique.
    Radiological Physics and Technology 01/2011; 4(2):109-20.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Our aim in this study was to determine an optimal delay time of hepatic arterial phase (HAP) imaging of hypervascular hepatocellular carcinomas (HCCs) in dynamic contrast-enhanced MDCT (DCE-CT) by use of the bolus-tracking method. The time-enhancement curves (TECs) of the aorta and the contrast of the hepatic arterial and portal system (APC) in the pharmacokinetic analysis were calculated. The clinical study included 41 patients with known or suspected HCC who underwent DCE-CT. The TECs of the aorta and the tumor-liver contrast (TLC) in the clinical study were calculated. On pharmacokinetic analysis, the peak aortic enhancement and the peak APC simulated under conditions of an injection duration of 30 s and an iodine load of 500 mg I/kg body weight were observed 18.5 and 22.5 s, respectively, after the trigger threshold (increased CT value 100 Hounsfield units), respectively. In the clinical study, the peak aortic enhancement and the peak TLC were observed 17.2 and 24.8 s after the trigger threshold, respectively. The optimal delay times until peak aortic enhancement and peak HAP were 15-17 and 19-21 s after the trigger threshold, respectively, under the following conditions: injection dose, 500 mg I/kg body weight; injection duration, 30 s; acquisition time, 5 s; and the trigger threshold. In addition, the peak TLC was achieved 4-7 s after the time to peak aortic enhancement.
    Radiological Physics and Technology 01/2011; 4(1):43-52.
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE To compare the diagnostic quality of diffusion-weighted (DW) imaging with regard to apparent diffusion coefficient (ADC) accuracy and DW image contrast for different breast lesions and normal breast tissue. METHOD AND MATERIALS Institutional review board approval and written informed consent were obtained. Seventy-five women (mean age 55.3, range 27 – 82) were examined with a 3.0 T MR imaging (MRI) system in this study. A total of 112 regions of interest were plotted in 67 malignant, 5 benign, and 75 normal tissue regions. All malignant tumors were verified pathologically, while benign tumors were confirmed by follow-up. Each ADC value was measured in single-shot echo-planar DW imaging with b-factors of 0 and 800 s/mm2, and 0 and 1500 s/mm2. Differences of ADC in tissue types were evaluated. The contrast of lesions on DWI was compared for two b-values (800 and 1500 s/mm2). Repeated-measures analysis of variance was used to assess lesion differentiation. RESULTS The contrast between normal mammary gland and tumor tissues was significantly higher in DWI with a b-value of 1500 s/mm2 than 800 s/mm2 in both invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS) (P < 0.001). Differential diagnosis between malignant and benign lesions was obtained using high b-value in 3.0 T MRI system. ADCs obtained with b-values of 800 and 1500 s/mm2 were significantly different for normal mammary gland, IDC, and DCIS. Accurate distinction between benign and malignant breast tumors was obtained by ADC using high b-values with a 3.0 T MRI system. CONCLUSION Optimal ADC discrimination and DWI contrast in 3.0 T MRI was obtained with high b-values. The method provided appropriate differentiation of benign and malignant breast tumors with high accuracy. CLINICAL RELEVANCE/APPLICATION Accurate differential diagnosis between benign and malignant breast tumors may be obtained by breast DW imaging and ADC using high b-value with a 3.0 T MRI system.
    0 Tesla: Does DW Imaging Using High b-value Really Show Overestimation?. Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the correlation between the peripheral hyperintense pattern of breast carcinoma on T2-weighted images (T2WI) and the early peripheral enhancement (EPE) on dynamic magnetic resonance imaging (MRI) and to examine the histological characteristics involved in the causes thereof. The signal intensity of 131 breast carcinomas of common type on T2WI was classified into four types and the correlations between the signal intensity and the histopathological subtypes were evaluated. We investigated correlation with the peripheral hyperintense pattern on a T2WI and other findings on MR images including EPE. In addition, we also investigated the histopathological characteristics in the lesions with a peripheral hyperintense pattern. The signal intensities of the lesions on T2WI demonstrated hyperintensity, isointensity, hypointensity, and a peripheral hyperintense pattern in 26 (20%), 66 (50%), 19 (15%), and 20 (15%) lesions, respectively. A peripheral hyperintense pattern correlated with the appearance of EPE (P < 0.0001) and the degree of central fibrosis (P < 0.0001). A peripheral hyperintense pattern on T2WI is a characteristic finding observed in breast carcinomas and correlated with the appearance of EPE. The appearance of a peripheral hyperintense pattern was affected by various histopathological features in the same manner as that observed for the formation of EPE.
    Journal of Magnetic Resonance Imaging 11/2010; 32(5):1117-23. · 2.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic resonance imaging (MRI) is useful in the quantitative evaluation of brain atrophy, because the superior contrast resolution facilitates separation of the gray and white matter. Quantitative assessment of brain atrophy has mainly been performed by manual measurement, which requires considerable time and effort to determine the brain volume. Therefore, computer-aided quantitative measurement methods for the diagnosis of brain atrophy are required. We have developed a method of segmenting the cerebrum, cerebellum-brainstem, and temporal lobe simultaneously on MR images obtained in a single sequence. It is important to measure the volume of not only these regions but also the frontal lobe in clinical use. However, for segmenting the frontal lobe, it is necessary to identify the Sylvian fissure and the central sulcus, which represent boundaries. Here, we developed a method of identifying the central sulcus from MR images obtained with a 1.5 T MRI scanner. The brain and the cerebrospinal fluid (CSF) regions were segmented using semiautomated segmentation method on MR images. The central sulcus shows an oblique line from the inside to the outside on the convexity view. The almost straight appearance of the central sulcus was used for segmentation of the central sulcus from the segmented CSF images. The central sulcus was identified with this technique in 77% of the images obtained by all sequences. This technique for identifying the central sulcus is very important not only for volumetry, but also for clinical diagnosis.
    Radiological Physics and Technology 09/2010; 4(1):53-60.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gd-EOB-DTPA is a new liver specific MRI contrast media. In the hepatobiliary phase, contrast media is trapped in normal liver tissue, a normal liver shows high intensity, tumor/liver contrast becomes high, and diagnostic ability improves. In order to indicate the degree of uptake of the contrast media, the enhancement ratio (ER) is calculated. The ER is obtained by calculating (signal intensity (SI) after injection-SI before injection) / SI before injection. However, because there is no linearity between contrast media concentration and SI, ER is not correctly estimated by this method. We discuss a method of measuring ER based on SI and T(1) values using the phantom. We used a column phantom, with an internal diameter of 3 cm, that was filled with Gd-EOB-DTPA diluted solution. Moreover, measurement of the T(1) value by the IR method was also performed. The ER measuring method of this technique consists of the following three components: 1) Measurement of ER based on differences in 1/T(1) values using the variable flip angle (FA) method, 2) Measurement of differences in SI, and 3) Measurement of differences in 1/T(1) values using the IR method. ER values calculated by these three methods were compared. In measurement made using the variable FA method and the IR method, linearity was found between contrast media concentration and ER. On the other hand, linearity was not found between contrast media concentration and SI. For calculation of ER using Gd-EOB-DTPA, a more correct ER is obtained by measuring the T(1) value using the variable FA method.
    Nippon Hoshasen Gijutsu Gakkai zasshi 05/2010; 66(5):502-8.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori (HP)-eradication therapy increases Runt domain transcription factor 3 (RUNX3) expression in the glandular epithelial cells in enlarged-fold gastritis. The aim of this study is to evaluate expression of the RUNX3 protein, the product of a gastric tumor suppression gene, and mutagenic oxidative stress in human gastric mucosal specimens obtained from patients with HP-induced enlarged-fold gastritis. Methods. RUNX3 expression was immunohistochemically scored and the degree of the mucosal oxidative stress was directly measured by the chemiluminescense (ChL) assay in the biopsy specimens. Results. RUNX3 expression was detected in the gastric epithelial cells. HP-eradication significantly increased RUNX3 expression in the glandular epithelium of the corpus, however, no change was observed in those of the antrum. A fourfold higher mucosal ChL value was observed in the corpus as compared with that in the antrum. HP-eradication significantly decreased the mucosal ChL values in both portions of the stomach to nearly undetectable levels. Conclusion. The glandular epithelium is exposed to a high level of carcinogenic oxidative stress and shows low levels of expression of the tumor suppressive molecule, RUNX3; however, this expression was restored after HP-eradication, suggesting the high risk of carcinogenesis associated with HP-induced enlarged-fold gastritis of the corpus.
    Journal of Clinical Biochemistry and Nutrition 05/2010; 46(3):259-64. · 2.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: True tracheal bronchus (TTB) is a rare anomaly in which a lobar or segmental ectopic bronchus arises from the trachea. We examined the frequency and multidetector computed tomography (MDCT) appearances of TTB. We retrospectively analyzed 9781 chest MDCT examinations. In cases in which there was an abnormal bronchus suggesting TTB on axial CT images, the following imaging of the abnormal bronchi was undertaken: multiplanar reformation (MPR), multiprojection volume reconstruction (MPVR), volume rendering (VR), and virtual endoscopy (VE). Of 9781 MDCT examinations, 30 TTBs were observed in 10 females and 20 males. The frequency of TTB was 0.21% among 4622 females, 0.39% among 5159 males (0.31 % in the overall patient population). TTBs arose from the right lateral wall of the trachea; 17 TTBs were of the displaced type and 13 of the supernumerary type. With the displaced type, all segments of the right upper lobe were supplied by the TTB in 8 patients, and the apical segment was supplied in 8 patients. With the supernumerary type, TTBs showed blind termination in 10 patients, and the TTB had a small lobule in 3 patients. All TTBs were clearly visualized on MPR, MPVR, VR, and VE. TTB was identified by MDCT with an incidence of 0.31%.
    Japanese journal of radiology 04/2010; 28(3):188-92. · 0.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In cases of suspected cranial trauma, cranial CT examinations should be performed to rule out pathology. There are some methods available for reducing intraocular doses; however, it is difficult for the operators to conduct the necessary measurements because of restrictions in time and patient mobility, especially in high-energy trauma cases. Therefore, we performed a head phantom study for intraocular dose evaluation of 64-slice multidetector CT examination in patients with suspected cranial trauma. Assuming that the orbitomeatal (OM) line and bed were vertical, a head phantom was tilted from 10 degrees caudally to 25 degrees cranially at 5-degree intervals. At each tilted position, the phantom was examined using a 64-section multidetector CT device using three acquisition protocols. Intraocular doses during each examination were measured using small dosimeters. Assuming that the OM line and bed were vertical, intraocular doses varied between 52 and 140%, 17-138%, and 90-142% during helical, non-helical, and helical CT angiographic examinations, respectively. Intraocular doses increased when the phantom was tilted cranially. If possible, the best way to reduce the intraocular dose is by angling the gantry cranially, tilting the head of each patient caudally and adopting a non-helical acquisition method. During procedure, the acquisition angle should be angled cranially more than 0 degrees based on the OM line. The estimation of intraocular dose using the acquisition angle and displayed volumetric CT dose index might be useful to evaluate the deterministic effect risks and to inform patients about the associated risks.
    European journal of radiology 02/2010; 79(2):283-7. · 2.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effectiveness of a positioning doll for radiography training (XPD) and acquiring the techniques of radiography was evaluated through performing radiography practice for the students in our school of radiological technologists and a questionnaire for radiological technologists. We made a ranking test composed of a five-grade evaluation system of the 39 students for the techniques of radiography before and after the practice, and questionnaires about the XPD were given to the same students after the practice. The questionnaires about affinities between human bodies and the XPD and effectiveness of the XPD for the education of students were also carried out in six radiological technologists to examine the effectiveness of the practice of radiography by using the XPD. The rankings of the students after the practice were significantly higher than those before the practice (p <0.01), and 85% of the students rated the practice using the XPD as useful for them in acquiring the techniques of radiography. Seventy-eight percent of the radiological technologists rated it useful for student education in radiography. In conclusion, it was suggested that practice using the XPD was effective in helping students to acquire the techniques of radiography. We would like to develop supplementary tools for fixing the XPD and using the practice of radiography in many ways and in new directions in the future.
    Nippon Hoshasen Gijutsu Gakkai zasshi 12/2009; 65(12):1650-7.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microcirculation is one of the susceptible targets in the pathogenesis of disorders caused by exogenous pathogens, such as the well-known bacterium, Helicobacter pylori (Hp). While extensive studies have been published on the kinetics of Hp infection, only a few have dealt with the microcirculatory aspects of Hp-induced disorders. This review summarizes the recent developments in the elucidation of the pathophysiology of disorders caused by Hp infection, focusing on the microcirculatory aspect. Animal and human studies were systematically reviewed to identify published data on the microcirculatory aspects of Hp infection. This updated summary of the microcirculatory aspects of Hp-induced disorders illustrates potential approaches that might be used to clarify the pathophysiology of the gastric and extragastric sequelae of Hp infection and the therapeutic strategies that could be adopted.
    Microcirculation (New York, N.Y.: 1994) 09/2009; 16(7):547-58. · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We compared effective doses for recent computed tomography (CT) examinations calculated based on International Commission on Radiological Protection publication number 103 (ICRP 103) with those calculated based on ICRP publication number 60 (ICRP 60), and considered the usefulness of the effective dose in CT dose evaluation. After placing radiophotoluminescence glass dosimeters (RPLDs) inside or outside an anthropomorphic phantom, we examined from the chest to the pelvis, cardiac, and cranial regions of the phantom. The absorbed dose was calculated by multiplying calibrated dose values of RPLD by the mass energy coefficient ratio. The effective dose was calculated as the sum total of the value for each tissue, which was multiplied by the equivalent dose according to the tissue weighting factor recommended in ICRP 103 and ICRP 60. Calculated effective doses based on ICRP 103 were different by –11% to +82% compared with those based on ICRP 60. The values of absorbed doses for selective tissues were relatively higher than the values for the effective dose. The effective dose represents only a mean dose value for an average human. Therefore, assessing the absolute dose of particular individuals in CT examinations based exclusively on the effective dose is not recommended.
    European Radiology 08/2009; 19(12):2855-61. · 4.34 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent linear accelerators can perform cone-beam computed tomography to correct setup errors immediately before dose delivery. We calculated the dose distribution with setup errors acquired from cone-beam computed tomography to determine a more realistic and individual effect of setup errors. The differences in dose distribution were analyzed. The setup errors of three patients who were irradiated in the neck, esophagus, and pelvic area were obtained retrospectively. We found that the maximum dose variances for the three cases were 19.9-35.9%. The maximum dose variance points were relatively far from the isocenter. The volume of the 10% dose difference had widths of 1.3-1.85 cm around the beam edges. The V95 and mean doses at the clinical target volume were mostly unchanged. Doses around the beam edges were more varied than those around the isocenter for every case. The dose on the spinal cord located near the beam edges varied by 5-10% compared with the dose of the radiotherapy plan in two of the cases. We demonstrated the individual dose distributions of the cases affected by daily setup errors for all fractions.
    Radiological Physics and Technology 07/2009; 2(2):151-8.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, several types of post-processing image filter which was designed to reduce noise allowing a corresponding dose reduction in CT images have been proposed and these were reported to be useful for noise reduction of CT images of adult patients. However, these have not been reported on adaptation for pediatric patients. Because they are not very effective with small (<20 cm) display fields of view, they could not be used for pediatric (e.g., premature babies and infants) body CT images. In order to solve this restriction, we have developed a new noise reduction filter algorithm which can be applicable for pediatric body CT images. This algorithm is based on a three-dimensional post processing, in which output pixel values are calculated by multi-directional, one-dimensional median filters on original volumetric datasets. The processed directions were selected except in in-plane (axial plane) direction, and consequently the in-plane spatial resolution was not affected by the filter. Also, in other directions, the spatial resolutions including slice thickness were almost maintained due to a characteristic of non-linear filtering of the median filter. From the results of phantom studies, the proposed algorithm could reduce standard deviation values as a noise index by up to 30% without affecting the spatial resolution of all directions, and therefore, contrast-to-noise ratio was improved by up to 30%. This newly developed filter algorithm will be useful for the diagnosis and radiation dose reduction of pediatric body CT images.
    Journal of Digital Imaging 06/2009; 23(6):806-18. · 1.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Inappropriate patient centering on the gantry changes the size of the localizer radiographs used for CT examinations, influencing the operation of CT automatic tube current modulation because tube current is controlled with information from localizer radiographs. The purpose of this study was to examine the influence of inappropriate patient centering on the gantry isocenter on automatic tube current modulation. An elliptical phantom was scanned with four automatic tube current modulation techniques after acquisition of localizer radiographs in the horizontal and vertical directions with the phantom center shifted from the gantry isocenter in the vertical direction. After scanning, the magnification rate of the frontal localizer radiographs, tube current-time product, and image noise were examined. On phantom studies, the magnification rate of localizer radiographs showed a linear relation to the vertical deviation of the phantom from the gantry isocenter. From 50 mm above to 50 mm below the gantry isocenter, tube current-time products ranged from 75% to 141% compared with those at the gantry isocenter. In addition, increases and decreases in the amount of image noise related to changes in tube current-time product were confirmed. Inappropriate patient centering causes misoperation of automatic tube current modulation systems, in which tube current is controlled with information from localizer radiographs, and thus causes increases in tube current or image noise.
    American Journal of Roentgenology 05/2009; 192(4):862-5. · 2.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Preoperative evaluation of bronchovascular structures is useful for prevention of accidents in pulmonary lobectomy. The purpose of this study was to examine the frequency and multidetector computed tomographic (CT) appearances of bronchovascular anomalies between the right middle and lower lobes. A total of 1116 consecutive chest CT examinations were analyzed in the present study. On display, the bronchovascular anomalies between the right middle and lower lobes were searched. When anomalous structures were observed, 3-dimensional images were reconstructed. Sixty-seven cases (6.0%) with anomalous findings were observed. In 20 cases (1.79%), the right middle lobe bronchus and artery supplied the lower lobe, whereas the lower lobe artery supplied the right middle lobe in 46 cases (4.12%). In 1 case (0.09%), the 2 patterns previously mentioned were observed concomitantly. Anomalous bronchovascular structures between the right middle and lower lobes were identified by a multidetector CT with an incidence of 6.0%. Knowledge of the frequency and CT features is useful for preoperative CT evaluation.
    Journal of computer assisted tomography 01/2009; 33(4):529-34. · 1.38 Impact Factor

Publication Stats

462 Citations
188.77 Total Impact Points


  • 1996–2013
    • Keio University
      • • Department of Internal Medicine
      • • School of Medicine
      Tokyo, Tokyo-to, Japan
  • 2003–2011
    • Kanazawa University
      • • Department of Radiological Technology
      • • Department of Quantum Medical Technology
      • • Graduate School of Medical Sciences
      Kanazawa, Ishikawa, Japan
    • Clinical Research Hospital, Tokyo
      Edo, Tōkyō, Japan
  • 2002–2010
    • Kanazawa Medical University
      • • Department of Radiology
      • • Department of Neurosurgery
      Kanazawa-shi, Ishikawa-ken, Japan
  • 2009
    • Hiroshima City Hospital
      Hirosima, Hiroshima, Japan
  • 2005–2008
    • University of Fukui
      • Division of Radiology
      Hukui, Fukui, Japan