Masahiro Yanagawa

Stanford Medicine, Stanford, California, United States

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Publications (29)74.13 Total impact

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    ABSTRACT: Purpose To perform volumetric analysis of stage I lung adenocarcinomas by using an automated computer program and to determine value of volumetric computed tomographic (CT) measurements associated with prognostic factors and outcome. Materials and Methods Consecutive patients (n = 145) with stage I lung adenocarcinoma who underwent surgery after preoperative chest CT were enrolled. By using volumetric automated computer-assisted analytic program, nodules were classified into three subgroups: pure ground glass, part solid, or solid. Total tumor volume, solid tumor volume, and percentage of solid volume of each cancer were calculated after eliminating vessel components. One radiologist measured the longest diameter of the solid tumor component and of total tumor with their ratio, which was defined as solid proportion. The value of these quantitative data by examining associations with pathologic prognostic factors and outcome measures (disease-free survival and overall survival) were analyzed with logistic regression and Cox proportional hazards regression models, respectively. Significant parameters identified at univariate analysis were included in the multiple analyses. Results All 22 recurrences occurred in patients with nodules classified as part solid or solid. Multiple logistic regression analysis revealed that percentage of solid volume of 63% or greater was an independent indicator associated with pleural invasion (P = .01). Multiple Cox proportional hazards regression analysis revealed that percentage of solid volume of 63% or greater was a significant indicator of lower disease-free survival (hazard ratio, 18.45 [95% confidence interval: 4.34, 78.49]; P < .001). Both solid tumor volume of 1.5 cm(3) or greater and percentage of solid volume of 63% or greater were significant indicators of decreased overall survival (hazard ratio, 5.92 and 9.60, respectively [95% confidence interval: 1.17, 30.33 and 1.17, 78.91, respectively]; P = .034 and .036, respectively). Conclusion Two volumetric measurements (solid volume, ≥1.5 cm(3); percentage of solid volume, ≥63%) were found to be independent indicators associated with increased likelihood of recurrence and/or death in patients with stage I adenocarcinoma. © RSNA, 2014.
    Radiology 04/2014; · 6.34 Impact Factor
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    ABSTRACT: To compare quality of ultra-low-dose thin-section computed tomography (CT) images of the lung reconstructed using model-based iterative reconstruction (MBIR) and adaptive statistical iterative reconstruction (ASIR) to filtered back projection (FBP) and to determine the minimum tube current-time product on MBIR images by comparing to standard-dose FBP images. Ten cadaveric lungs were scanned using 120 kVp and four different tube current-time products (8, 16, 32, and 80 mAs). Thin-section images were reconstructed using MBIR, three ASIR blends (30%, 60%, and 90%), and FBP. Using the 8-mAs data, side-to-side comparison of the four iterative reconstruction image sets to FBP was performed by two independent observers who evaluated normal and abnormal findings, subjective image noise, streak artifact, and overall image quality. Image noise was also measured quantitatively. Subsequently, 8-, 16-, and 32-mAs MBIR images were compared to standard-dose FBP images. Comparisons of image sets were analyzed using the Wilcoxon signed rank test with Bonferroni correction. At 8 mAs, MBIR images were significantly better (P < .005) than other reconstruction techniques except in evaluation of interlobular septal thickening. Each set of low-dose MBIR images had significantly lower (P < .001) subjective and objective noise and streak artifacts than standard-dose FBP images. Conspicuity and visibility of normal and abnormal findings were not significantly different between 16-mAs MBIR and 80-mAs FBP images except in identification of intralobular reticular opacities. MBIR imaging shows higher overall quality with lower noise and streak artifacts than ASIR or FBP imaging, resulting in nearly 80% dose reduction without any degradations of overall image quality.
    Academic radiology 04/2014; · 2.09 Impact Factor
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    ABSTRACT: Purpose To assess the variability of computed tomography (CT) patterns in patients with pathologic nonspecific interstitial pneumonia (NSIP) and to evaluate correlation of CT patterns with new idiopathic pulmonary fibrosis (IPF) classification guidelines, including pathologic diagnosis and predicted mortality. Materials and Methods The ethical review boards of the five institutions that contributed cases waived the need for informed consent for retrospective review of patient records and images. The study included 114 patients with (a) a pathologic diagnosis of idiopathic NSIP (n = 39) or (b) a pathologic diagnosis of usual interstitial pneumonia (UIP) and a clinical diagnosis of IPF (n = 75). Two groups of independent observers evaluated the extent and distribution of various CT findings and identified the following five patterns: UIP, possible UIP, indeterminate (either UIP or NSIP), NSIP, and suggestive of an alternative diagnosis. CT findings were compared with pathologic diagnoses and outcome from clinical findings by using the log-rank test and Kaplan-Meier curves. Results Radiologists classified 17 cases as UIP, 24 as possible UIP, 13 as indeterminate (either UIP or NSIP), and 56 as NSIP. In 35 of 39 patients with pathologic NSIP, a diagnosis of NSIP was made with CT. On the basis of CT interpretations, the mean overall survival time of patients with UIP, possible UIP, indeterminate findings, or NSIP was 33.5, 73.0, 101.0, and 140.2 months, respectively. Outcome of patients with a CT diagnosis of UIP was significantly worse than that of patients with a pattern of possible UIP, indeterminate findings, or NSIP (log-rank test: P = .013, P = .018, and P < .001, respectively). Conclusion CT pattern in patients with pathologic NSIP is more uniform than that in patients with pathologic UIP, and CT NSIP pattern is associated with better patient outcome than is CT UIP pattern. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 03/2014; · 6.34 Impact Factor
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    ABSTRACT: Rationale and Objectives To compare quality of ultra-low-dose thin-section computed tomography (CT) images of the lung reconstructed using model-based iterative reconstruction (MBIR) and adaptive statistical iterative reconstruction (ASIR) to filtered back projection (FBP) and to determine the minimum tube current–time product on MBIR images by comparing to standard-dose FBP images. Materials and Methods Ten cadaveric lungs were scanned using 120 kVp and four different tube current–time products (8, 16, 32, and 80 mAs). Thin-section images were reconstructed using MBIR, three ASIR blends (30%, 60%, and 90%), and FBP. Using the 8-mAs data, side-to-side comparison of the four iterative reconstruction image sets to FBP was performed by two independent observers who evaluated normal and abnormal findings, subjective image noise, streak artifact, and overall image quality. Image noise was also measured quantitatively. Subsequently, 8-, 16-, and 32-mAs MBIR images were compared to standard-dose FBP images. Comparisons of image sets were analyzed using the Wilcoxon signed rank test with Bonferroni correction. Results At 8 mAs, MBIR images were significantly better (P < .005) than other reconstruction techniques except in evaluation of interlobular septal thickening. Each set of low-dose MBIR images had significantly lower (P < .001) subjective and objective noise and streak artifacts than standard-dose FBP images. Conspicuity and visibility of normal and abnormal findings were not significantly different between 16-mAs MBIR and 80-mAs FBP images except in identification of intralobular reticular opacities. Conclusions MBIR imaging shows higher overall quality with lower noise and streak artifacts than ASIR or FBP imaging, resulting in nearly 80% dose reduction without any degradations of overall image quality.
    Academic Radiology. 01/2014;
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    ABSTRACT: Purpose To evaluate the intracystic MRI [magnetic resonance imaging] signal intensity of mediastinal cystic masses on T2-weighted images. Materials and Methods A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI-mSI to standard deviation (SD) of background noise (|cSI-mSI|/SD = CNR [contrast-to-noise ratio]) were measured. Results The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test). Conclusions Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions.
    European Journal of Radiology. 01/2014;
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    ABSTRACT: Recently, PET response criteria in solid tumors (PERCIST) have been proposed as a new standardized method to assess chemotherapeutic response metabolically and quantitatively. The aim of this study was to evaluate therapeutic response to neoadjuvant chemotherapy for locally advanced esophageal cancer, comparing PERCIST with the currently widely used response evaluation criteria in solid tumors (RECIST). Fifty-one patients with locally advanced esophageal cancer who received neoadjuvant chemotherapy (5-fluorouracil, adriamycin, and cisplatin), followed by surgery were studied. Chemotherapeutic lesion responses were evaluated using (18)F-FDG PET and CT according to the RECIST and PERCIST methods. The PET/CT scans were obtained before chemotherapy and about 2 wk after completion of chemotherapy. Associations were statistically analyzed between survival (overall and disease-free survival) and clinicopathologic results (histology [well-, moderately, and poorly differentiated squamous cell carcinoma], lymphatic invasion, venous invasion, clinical stage, pathologic stage, resection level, reduction rate of tumor diameter, reduction rate of tumor uptake, chemotherapeutic responses in RECIST and PERCIST, and pathologic response). There was a significant difference in response classification between RECIST and PERCIST (Wilcoxon signed-rank test, P < 0.0001). Univariate analysis showed that lymphatic invasion, venous invasion, resection level, pathologic stage, and PERCIST were significant factors associated with disease-free or overall survival in this study. Although multivariate analysis demonstrated that venous invasion (disease-free survival: hazard ratio [HR] = 4.519, P = 0.002; overall survival: HR = 5.591, P = 0.003) and resection level (disease-free survival: HR = 11.078, P = 0.001) were the significant predictors, PERCIST was also significant in noninvasive therapy response assessment before surgery (disease-free survival: HR = 4.060, P = 0.025; overall survival: HR = 8.953, P = 0.034). RECIST based on the anatomic size reduction rate did not demonstrate the correlation between therapeutic responses and prognosis in patients with esophageal cancer receiving neoadjuvant chemotherapy. However, PERCIST was found to be the strongest independent predictor of outcomes. Given the significance of noninvasive radiologic imaging in formulating clinical treatment strategies, PERCIST might be considered more suitable for evaluation of chemotherapeutic response to esophageal cancer than RECIST.
    Journal of Nuclear Medicine 05/2012; 53(6):872-80. · 5.77 Impact Factor
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    ABSTRACT: Gastrointestinal stromal tumors (GISTs) and malignant lymphomas (MLs) in the abdomen are often observed as tumors of unknown origin on F-18 FDG PET/CT. The purpose of this study was to evaluate the intratumoral metabolic heterogeneity of F-18 FDG uptake on PET to determine if it might be helpful to discriminate between these tumors. The F-18 FDG PET/CT findings of 21 large abdominal tumors were retrospectively evaluated (9 GISTs and 12 MLs). Intratumoral heterogeneity was evaluated by visual scoring (visual score: 0, homogeneous; 1, slightly heterogeneous; 2, moderately heterogeneous; 3, highly heterogeneous) and by the cumulative standardized uptake value (SUV) histograms on transaxial PET images at the maximal cross-sectional tumor diameter. Percent tumor areas above a threshold from 0 to 100% of the maximum SUV were plotted and the area under curve of the cumulative SUV histograms (AUC-CSH) was used as a heterogeneity index, where lower values corresponded with increased heterogeneity. Correlation between the visual score and the AUC-CSH was investigated by the Spearman's rank test. GISTs exhibited heterogeneous uptake of F-18 FDG, whereas MLs showed rather homogeneous uptake on visual analysis (visual score: 2.67 ± 0.50 and 0.58 ± 0.79, respectively; p < 0.001). The AUC-CSH was significantly lower for the GISTs than for the MLs (0.41 ± 0.14 and 0.64 ± 0.08, respectively; p < 0.001). Significant correlations were observed between the visual score and the AUC-CSH (ρ = -0.866, p < 0.001). GISTs exhibited significantly heterogeneous intratumoral tracer uptake as compared with the MLs. Evaluation of the intratumoral heterogeneity of F-18 FDG uptake may help in the discrimination between these tumors.
    Annals of Nuclear Medicine 12/2011; 26(3):222-7. · 1.41 Impact Factor
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    ABSTRACT: The aim of this study was to correlate high-resolution CT (HRCT) findings at the site of biopsy with the whole lung CT and pathologic diagnoses in usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP). The study included 35 patients (25 UIP and 10 NSIP) diagnosed both pathologically and clinically. 81 surgical biopsy specimens (54 UIP, and 27 NSIP) and extracted areas corresponding to biopsy sites on HRCT were analyzed. CT interpretations were compared with pathological diagnoses in both extracted images and the whole lung. Concordant and discordant cases in multiple extracted images were divided and analyzed. Then the whole cases were categorized by including or not at least one UIP diagnosis of extracted images and evaluated. The diagnoses in extracted sites significantly correlated with pathological diagnoses (p=0.047). There were significant differences in the concordances of extracted images compared with the diagnosis of whole lung and pathology (p=0.008, 0.003, respectively). All 7 cases that were not concordant were diagnosed as radiological UIP with whole lung CT. The cases with at least one UIP diagnosis of extracted CT images were diagnosed as UIP in pathology more frequently (18 in 25) (p=0.007). Radiological UIP in whole CT had more frequently discordant diagnoses from multiple extracted images than NSIP. And there were more cases in pathological UIP that included at least one UIP diagnosis of extracted images compared with pathological NSIP.
    European journal of radiology 12/2011; 81(10):2919-24. · 2.65 Impact Factor
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    ABSTRACT: Evaluation of detection of lung nodules by C-arm CT (CACT) is important before this procedure can be used to guide percutaneous lung interventions. To compare the efficacy of CACT with CT in the detection of pulmonary nodules using a phantom lung. A phantom lung containing 12 phantom nodules in four sizes (5 mm/8 mm/10 mm/12 mm) and three CT values (one solid nodule, +100 HU; two ground glass nodules, -630 and -800 HU) was used. Six sessions of CACT (slice thickness 4.5 mm) and CT (slice thickness 5 mm) were performed. In each session, the locations of nodules were arbitrarily changed in the phantom. Three radiologists assessed the detection of a total of 72 nodules. Statistical analysis was performed for the sensitivity and positive predictive value of lung nodules between CACT and CT by the McNemar test and paired t-test (P < 0.05). Sensitivity did not differ between CACT and CT, respectively (reader 1, 82% vs. 88%, P = 0.22; reader 2, 82% vs. 78%, P = 0.37; reader 3, 79% vs. 83%, P = 0.48). For nodules of 8 mm or larger, the sensitivity increased for each reader and showed no significant difference between CACT vs. CT. The positive predictive value did not differ between CACT and CT. In this phantom study, CT and CACT show similar sensitivity for the detection of pulmonary nodules. CACT could be used in percutaneous interventional procedures in the lungs.
    Acta Radiologica 11/2011; 52(9):964-8. · 1.33 Impact Factor
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    ABSTRACT: To evaluate the effects of ASIR on CAD system of pulmonary nodules using clinical routine-dose CT and lower-dose CT. Thirty-five patients (body mass index, 22.17 ± 4.37 kg/m(2)) were scanned by multidetector-row CT with tube currents (clinical routine-dose CT, automatically adjusted mA; lower-dose CT, 10 mA) and X-ray voltage (120 kVp). Each 0.625-mm-thick image was reconstructed at 0%-, 50%-, and 100%-ASIR: 0%-ASIR is reconstructed using only the filtered back-projection algorithm (FBP), while 100%-ASIR is reconstructed using the maximum ASIR and 50%-ASIR implies a blending of 50% FBP and ASIR. CAD output was compared retrospectively with the results of the reference standard which was established using a consensus panel of three radiologists. Data were analyzed using Bonferroni/Dunn's method. Radiation dose was calculated by multiplying dose-length product by conversion coefficient of 0.021. The consensus panel found 265 non-calcified nodules ≤ 30 mm (ground-glass opacity [GGO], 103; part-solid, 34; and solid, 128). CAD sensitivity was significantly higher at 100%-ASIR [clinical routine-dose CT, 71% (overall), 49% (GGO); lower-dose CT, 52% (overall), 67% (solid)] than at 0%-ASIR [clinical routine-dose CT, 54% (overall), 25% (GGO); lower-dose CT, 36% (overall), 50% (solid)] (p<0.001). Mean number of false-positive findings per examination was significantly higher at 100%-ASIR (clinical routine-dose CT, 8.5; lower-dose CT, 6.2) than at 0%-ASIR (clinical routine-dose CT, 4.6; lower-dose CT, 3.5; p<0.001). Effective doses were 10.77 ± 3.41 mSv in clinical routine-dose CT and 2.67 ± 0.17 mSv in lower-dose CT. CAD sensitivity at 100%-ASIR on lower-dose CT is almost equal to that at 0%-ASIR on clinical routine-dose CT. ASIR can increase CAD sensitivity despite increased false-positive findings.
    European journal of radiology 10/2011; 81(10):2877-86. · 2.65 Impact Factor
  • Masahiro Yanagawa, Noriyuki Tomiyama
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    ABSTRACT: Thymic epithelial tumors, such as thymomas and thymic carcinomas, are the most common primary neoplasms of the mediastinum. In 1999, the World Health Organization (WHO) proposed a consensus classification of thymic epithelial tumors based on the morphology of the epithelial cells and the ratio of lymphocytes to epithelial cells, which was revised in 2004. The latest classification system stratifies thymic epithelial tumors into six categories: types A, AB, B1, B2, B3, and thymic carcinoma. This article describes the prediction of thymoma histology and stage on the basis of radiographic criteria by reviewing the following: the WHO histologic classification of thymic epithelial tumors, the clinical staging of thymomas based on prognosis, and the radiographic appearance of thymomas according to the WHO histologic classification.
    Thoracic Surgery Clinics 02/2011; 21(1):1-12, v.
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    ABSTRACT: We investigated the image quality of multiplanar reconstruction (MPR) using adaptive statistical iterative reconstruction (ASIR). Inflated and fixed lungs were scanned with a garnet detector CT in high-resolution mode (HR mode) or non-high-resolution (HR) mode, and MPR images were then reconstructed. Observers compared 15 MPR images of ASIR (40%) and ASIR (80%) with those of ASIR (0%), and assessed image quality using a visual five-point scale (1, definitely inferior; 5, definitely superior), with particular emphasis on normal pulmonary structures, artefacts, noise and overall image quality. The mean overall image quality scores in HR mode were 3.67 with ASIR (40%) and 4.97 with ASIR (80%). Those in non-HR mode were 3.27 with ASIR (40%) and 3.90 with ASIR (80%). The mean artefact scores in HR mode were 3.13 with ASIR (40%) and 3.63 with ASIR (80%), but those in non-HR mode were 2.87 with ASIR (40%) and 2.53 with ASIR (80%). The mean scores of the other parameters were greater than 3, whereas those in HR mode were higher than those in non-HR mode. There were significant differences between ASIR (40%) and ASIR (80%) in overall image quality (p<0.01). Contrast medium in the injection syringe was scanned to analyse image quality; ASIR did not suppress the severe artefacts of contrast medium. In general, MPR image quality with ASIR (80%) was superior to that with ASIR (40%). However, there was an increased incidence of artefacts by ASIR when CT images were obtained in non-HR mode.
    The British journal of radiology 11/2010; 84(1000):335-41. · 2.11 Impact Factor
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    ABSTRACT: To evaluate thin-section computed tomography (CT) images of the lung reconstructed using adaptive statistical iterative reconstruction (ASIR) on standard- and reduced-dose CT. Eleven cadaveric lungs were scanned by multidetector-row CT with two different tube currents (standard dose, 400 mA; reduced dose, 10 mA). The degree of ASIR was classified into six different levels: 0% (non-ASIR), 20%, 40%, 60%, 80%, and 100% (maximum-ASIR). The ASIR (20%, 60%, and 100%) images were compared with the ASIR (0%) images and assessed visually by three independent observers for image quality using a 7-point scale. The evaluation items included abnormal CT findings, normal lung structures, and subjective visual noise. The median scores assigned by the three observers were analyzed statistically. Quantitative noise was calculated by measuring the standard deviation in a circular region of interest on each selected image of ASIR (0%-100%). On standard-dose CT, the overall image quality significantly improved with increasing degree of ASIR (P ≤ .009, Wilcoxon signed-ranks test with Bonferroni correction). As ASIR increased, however, intralobular reticular opacities and peripheral vessels tended to be obscure. On reduced-dose CT, the overall image quality of ASIR (100%) was significantly better than that of ASIR (20%) (P ≤ .009). As ASIR increased, however, intralobular reticular opacities tended to be obscure. Using ASIR significantly reduced subjective and quantitative image noise on both standard- and reduced-dose CT (P < .001, Bonferroni/Dunn's method). ASIR improves the image quality by decreasing image noise. Maximum-ASIR may be needed for improving image quality on highly reduced-dose CT. However, excessive ASIR may obscure subtle shadows.
    Academic radiology 10/2010; 17(10):1259-66. · 2.09 Impact Factor
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    ABSTRACT: The aims of this study were to compare diagnostic accuracy between computed tomography (CT)-guided percutaneous cutting needle biopsy (PCNB) and surgery or open biopsy for thymic epithelial tumors in accordance with the World Health Organization (WHO) classification and to evaluate computed tomographic diagnosis additionally. Subjects were 20 patients (11 men, 9 women) in whom CT, CT-guided PCNB, and surgery had been performed for anterior mediastinal tumors. All diagnoses of both CT-guided PCNB and surgery or open biopsy were made in accordance with the WHO classification. Computed tomographic diagnoses were performed by two radiologists on the basis of radiologic characteristics previously reported according to the simplified WHO classification (types A and AB, type B1, types B2 and B3, and thymic carcinoma). The concordance of the WHO classification or the simplified WHO classification between the diagnosis on either CT or CT-guided PCNB and that on surgery was evaluated using the weighted kappa statistic. The histologic classifications on the basis of surgical resection specimens were as follows: type A, n = 3; type AB, n = 5; type B1, n = 3; type B2, n = 4; type B3, n = 4; and thymic carcinoma, n = 1. The overall concordance with the diagnosis according to the WHO classification established using CT-guided PCNB specimens (weighted kappa = 0.757) was higher than that using computed tomographic diagnosis (weighted kappa = 0.437). CT-guided PCNB is a technique with good concordance of the WHO classification of thymic epithelial tumors between the diagnoses of surgery or open biopsy.
    Academic radiology 06/2010; 17(6):772-8. · 2.09 Impact Factor
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    ABSTRACT: To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors. The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed by using the Heitzman method were scanned by using both CT with garnet-based detectors and CT with conventional detectors. Tube current was 400 mA for standard-dose and 10 mA for reduced-dose CT, and voltage was 120 kVp. Either normal scan mode with 984 views (conventional and garnet-based detectors) or high-resolution mode with 2496 views was used. Image quality at conventional-detector CT and garnet-based-detector CT in all modes was graded by two independent observers with a five-point scale. The evaluation items included normal lung structures, subjective visual noise, and abnormal CT findings. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest on each selected image. At standard-dose CT, image quality at CT with garnet-based detectors (high-resolution mode) was significantly improved (P < .001, Tukey-Kramer). However, there was no significant difference between quantitative image noise measurements (P > or = .24). At reduced-dose CT, only noise differed significantly, with both subjective visual noise and quantitative image noise measurements significantly greater at CT with garnet-based detectors (high-resolution mode) (P < or = .01). There was no significant difference in image quality except for noise between conventional-detector CT and garnet-based-detector CT (P > or = .06). The image quality of standard-dose garnet-based-detector CT (high-resolution) was significantly improved. Although highly reduced-dose garnet-based-detector CT (high-resolution mode) provided more image noise, overall image quality was not different between conventional-detector CT and garnet-based-detector CT.
    Radiology 06/2010; 255(3):944-54. · 6.34 Impact Factor
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    ABSTRACT: To evaluate a custom-developed software for analyzing malignant degrees of small peripheral adenocarcinomas on volumetric CT data compared to pathological prognostic factors. Forty-six adenocarcinomas with a diameter of 2cm or less from 46 patients were included. The custom-developed software can calculate the volumetric rates of solid parts to whole nodules even though solid parts show a punctate distribution, and automatically classify nodules into the following six types according to the volumetric rates of solid parts: type 1, pure ground-glass opacity (GGO); type 2, semiconsolidation; type 3, small solid part with a GGO halo; type 4, mixed type with an area that consisted of GGO and solid parts which have air-bronchogram or show a punctate distribution; type 5, large solid part with a GGO halo; and type 6, pure solid type. The boundary between solid portion and GGO on CT was decided using two threshold selection methods for segmenting gray-scale images. A radiologist also examined two-dimensional rates of solid parts to total opacity (2D%solid) which was already confirmed with previous reports. There were good agreements between the classification determined by the software and radiologists (weighted kappa=0.778-0.804). Multivariate logistic regression analyses showed that both 2D%solid and computer-automated classification were significantly useful in estimating lymphatic invasion (p=0.0007, 0.0027), vascular invasion (p=0.003, 0.012), and pleural invasion (p=0.021, 0.025). Using our custom-developed software, it is feasible to predict the pathological prognostic factors of small peripheral adenocarcinomas.
    Lung cancer (Amsterdam, Netherlands) 04/2010; 70(3):286-94. · 3.14 Impact Factor
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    ABSTRACT: The aim of this study was to determine the computed tomography (CT) values of various pulmonary abnormalities in cubic region of interest (ROI) and square ROI and evaluate the CT findings by histogram analysis in the ROI. The study included 89 patients with the following 8 pulmonary CT patterns: normal lung, ground-glass attenuation, fine reticular opacity, coarse reticular opacity, honeycombing, airspace consolidation, nodular opacity, and emphysema. Cubic and square ROIs were selected in each CT pattern, and 5 values (contrast, variance, entropy, skewness, and kurtosis) were calculated. In the histogram of ground-glass attenuation, fine reticular opacity, and coarse reticular opacity, peaks had moved to the right compared with the normal lung. Only emphysema had higher contrast and lower entropy than the normal lung (P < 0.001). The other abnormalities had lower contrast and higher entropy than the normal lung. In conclusion, the shapes of histograms were characteristic of various abnormalities of the lung, and the values reflected the histogram quantitatively.
    Journal of computer assisted tomography 08/2009; 33(5):731-8. · 1.38 Impact Factor
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    ABSTRACT: The aim of this study was to measure the volume of each pulmonary segment by volumetric computed tomography (CT) data using a newly developed three-dimensional software application and to identify the differences between those with chronic obstructive pulmonary disease (COPD) and controls. CT scans of 11 COPD patients and 16 controls were included. The volume of each pulmonary segment was measured by each of two operators to evaluate the reproducibility of the software. This measured volume was then divided by the total lung volume to revise individual variations. Volumes of the right (rt) S2, rt S5, left (lt) S1 + S2, lt S3, and lt S5 were significantly larger in COPD patients than in controls (P < 0.05). Regarding the ratio of the volume of each pulmonary segment per total lung volume, the areas of rt S2 and lt S1 + S2 were significantly larger in COPD patients than in controls (P < 0.05), whereas lt S10 was significantly smaller in COPD patients than in controls (P < 0.05). We measured the volume of each pulmonary segment based on volumetric CT data using this software. In addition, we demonstrated that the upper lung volume of COPD subjects was larger than that of controls, whereas the lower lung volumes were almost the same.
    Japanese journal of radiology 05/2009; 27(3):115-22. · 0.73 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the reproducibility of volumetric software evaluation and manual evaluation of tumour growth. Three observers manually evaluated whether tumour volume was increasing, if it was unchanged, or if it had decreased in size in 2 serial CT examinations of 45 solid lung cancers. The tumour volumes were calculated 3 times using volumetric software and were evaluated using the same classifications as for manual evaluation. Both data sets were divided into three groups: growth or reduction with consistency among all three evaluations (group A), growth or reduction with consistency between only two evaluations (group B), and others (group C). The volume variation and relative volume variation were calculated from the median volumes measured by volumetric software. Although all 45 tumours were categorised in group A by volumetric software, only 21 tumours were categorised in group A by manual assessment. The relative volume variation of the manual assessment was 88.5 +/- 76.5%, 20.8 +/- 28.3% and 12.9 +/- 12.8% in group A, B and C, respectively. Significant differences were found between groups A and B (p<0.01) and between groups A and C (p<0.001). Inconsistency is often seen in manual assessment; in contrast, evaluation using volumetric software has good reproducibility, even when the relative change in tumour volume is small.
    The British journal of radiology 04/2009; 82(981):742-7. · 2.11 Impact Factor
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    ABSTRACT: Most studies of computer-aided detection (CAD) for pulmonary nodules have focused on solid nodule detection. The aim of this study was to evaluate the performance of a commercially available CAD system in the detection of pulmonary nodules with or without ground-glass opacity (GGO) using 64-detector-row computed tomography compared to visual interpretation. Computed tomographic examinations were performed on 48 patients with existing or suspicious pulmonary nodules on chest radiography. Three radiologists independently reported the location and pattern (GGO, solid, or part solid) of each nodule candidate on computed tomographic scans, assigned each a confidence score, and then analyzed all scans using the CAD system. A reference standard was established by a consensus panel of different radiologists, who found 229 noncalcified nodules with diameters > or = 4 mm. True-positive and false-positive results and confidence levels were used to generate jackknife alternative free-response receiver-operating characteristic plots. The sensitivity of GGO for 3 radiologists (60%-80%) was significantly higher than that for the CAD system (21%) (McNemar's test, P < .0001). For overall and solid nodules, the figure-of-merit values without and with the CAD system were significantly different (P = .005-.04) on jackknife alternative free-response receiver-operating characteristic analysis. For GGO and part-solid nodules, the figure-of-merit values with the CAD system were greater than those without the CAD system, indicating no significant differences. Radiologists are significantly superior to this CAD system in the detection of GGO, but the CAD system can still play a complementary role in detecting nodules with or without GGO.
    Academic radiology 04/2009; 16(8):924-33. · 2.09 Impact Factor