Masahiro Yanagawa

Stanford Medicine, Stanford, California, United States

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Publications (47)76.77 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: To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images. 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. 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). 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 03/2014; · 2.65 Impact Factor
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    ABSTRACT: This study aimed to evaluate whether dual-energy computed tomography can reduce metal artifacts and improve detection of pulmonary nodules. Twelve simulated nodules were randomly placed inside a chest phantom with a pacemaker. Then, dual-energy computed tomography was performed, and 5 virtual monochromatic images at 40, 50, 65, 100, and 140 keV were reconstructed with 5- and 0.625-mm slice thicknesses. Two independent observers assessed the metal artifact (3-point scale from 1, none, to 3, severe) and detection of the nodule (5-point scale from 1, definitely absent, to 5, definitely present). Statistical analysis was performed with a P value of less than 0.01 (0.05/5). With both slice thicknesses, the metallic artifact increased at 40 or 50 keV and decreased at 100 or 140 keV relative to that at 65 keV (P < 0.01). The nodule detection score was not significantly different between each kiloelectron volt level with the 0.625-mm slice thickness; however, the score was significantly worse at 40 keV compared to 65 keV (P < 0.01) with the 5-mm slice thickness. High monochromatic energy images can reduce metal artifacts without a change in nodule detection score. Low monochromatic energy images increase metal artifacts and worsen nodule detection in thick slices.
    Journal of computer assisted tomography 01/2013; 37(5):707-11. · 1.38 Impact Factor
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    ABSTRACT: PURPOSE To evaluate thin-section CT images of the lung reconstructed using ASiR and MBIR on ultralow dose CT by comparing to filtered back-projection (FBP). METHOD AND MATERIALS We obtained approval from our internal Ethics Review Board. Ten cadaveric lungs inflated and fixed by the method of Heitzman were scanned by CT (CT750HD; GE). CT images were obtained with a 0.625 mm-detector collimation, detector pitch (0.984:1), 0.4 sec-gantry rotation, 512x512 matrix, 120 kV, 20mA, and non-high resolution mode. All CT images were reconstructed at 0.625-mm slice thickness and 20-cm field of view with FBP, ASiR (ASiR30%,ASiR60%, and ASiR90%), and MBIR. Compared to FBP, the following CT findings were graded on a 5-point scale (1:worst <2<3:equal<4<5:excellent) by two independent observers:Normal findings (vessels, bronchi, bronchiole, interlobar pleura);Abnormal findings (ground-glass opacity, consolidation, cyst, micro-, small-, large-nodules, interlobular septal thickening, intralobular reticular opacities, bronchiectasis);Subjective image noise;Artifact; and Overall image quality. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest (200 mm2) defined by an electric cursor on commercially available software (ImageJ). Statistical analyses were performed with Friedman test and repeated measures ANOVA. RESULTS In all normal and abnormal findings, each score was the highest in MBIR. In particular, with regard to vessels, bronchi, bronchiole, ground-glass opacity, micro- and small-nodules, increasing degree of ASiR significantly made them distinct (p<0.001). Moreover, MBIR improved them more clearly than ASiR. Using ASiR or MBIR significantly reduced subjective and quantitative image noise (mean±SD) (p<0.001):FBP (24.7±2.2), ASIR30% (21.6±2.0), ASiR60% (18.5±1.8), ASiR90% (15.5±1.6), and MBIR (2.71±1.1). The increasing degree of ASiR significantly decreased artifact, and MBIR further did (p<0.001). Eventually, score (mean±SD) of overall image quality was significantly higher in order of MBIR(4.96±0.17), ASiR90%(4.54±0.50), ASiR60%(3.54±0.50), and ASiR30%(3.00±0.00) (p<0.001). CONCLUSION Both ASiR and MBIR improve the image quality on ultralow dose CT. In particular, MBIR can provide the best image quality by decreasing image noise and artifact. CLINICAL RELEVANCE/APPLICATION In clinical practice, MBIR might be the most useful for reducing radiation dose without image degradation on chest CT.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE To evaluate the clinical utility of the motion-artifact-reducing software for the dual-shot energy subtraction radiography on a direct conversion flat-panel detector system. METHOD AND MATERIALS 42 nodules of 28 patients, which were confirmed by chest CT examination, were included in this study. Dual energy subtraction radiography was performed in all patients. The lung field was divided into 4 lung fields (right, left × upper, lower), and 10 readers evaluated the chest radiograph, soft tissue image and bone image without the motion-artifact-reducing software. Those with the motion-artifact-reducing software were also evaluated one month later. The scores of the nodule detection were assigned from 0 (definitely normal) to 100 (definitely abnormal) by readers’ confidence. The sensitivity of nodule detection was calculated with the score of not less than 90 in both lung and in 4 lung fields, and the statistical analysis was performed with paired t-test. RESULTS The sensitivity with the motion-artifact-reducing software (right lung: 45.9, left lung: 24.6) was significantly better than that without the motion-artifact-reducing software (right lung: 36.9, left lung: 17.7) in both lung (p<0.05). There was not a significant difference between the sensitivity with the motion-artifact-reducing software and that without the motion-artifact-reducing software in left upper, left lower and right upper lung field, whereas The sensitivity with the motion-artifact-reducing software (43.8) was significantly better than that without the motion-artifact-reducing software (31.9) in right lower lung field (p<0.05). CONCLUSION The motion-artifact-reducing software increased the sensitivity of pulmonary nodule detection, especially in right lower lung field. CLINICAL RELEVANCE/APPLICATION The motion-artifact-reducing software might have the potential to improve the nodule detection in the dual-shot energy subtraction radiography.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE The aim of this study was to evaluate the appearances on high-resolution CT (HRCT) and the correlation with pathological diagnosis and the mortality in the cases with nonspecific interstitial pneumonia (NSIP) comparing to those with usual interstitial pneumonia (UIP). METHOD AND MATERIALS The study included 114 patients with idiopathic NSIP (n=39) and UIP (n=75) diagnosed by both clinical and pathological diagnosis. Two independent observer groups respectively evaluated the extent and the distribution of various CT findings and determined the following five diagnoses; a. UIP pattern, b. possible UIP c. UIP or NSIP pattern, D. NSIP pattern and E. Suggestive of alternative diagnosis. CT findings were compared with the pathological diagnosis and the prognosis in clinical. RESULTS Radiologists classified as 17 cases of UIP pattern, 24 cases of possible UIP, 13 cases of UIP or NSIP pattern, 56 cases of NSIP pattern and 4 cases of suggestive of alternative diagnosis. In comparison with pathological diagnosis, UIP pattern, possible UIP pattern and UIP or NSIP pattern had pathological UIP except for each one case. The mean survival of UIP pattern, possible UIP, UIP or NSIP pattern, NSIP pattern was 33.5, 73.0, 101.0 and 140.2 months, respectively. The prognosis of definite UIP was not significantly different from that of the other 3 categories (log rank test: p=0.013, 0.018, <0.001 respectively). CONCLUSION Although the cases with pathological UIP tended to have various CT pattern, there were less variability of CT pattern in the cases with pathological NSIP. Radiological diagnosis was correlated with the mortality. CLINICAL RELEVANCE/APPLICATION Radiological diagnoses were correlated with the mortality and would be useful for predictors of prognosis.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE To evaluate whether virtual monochromatic image acquired by dual energy computed tomography (CT) can reduce metal artifact and can improve the detection of pulmonary nodules. METHOD AND MATERIALS Chest phantom and 12 simulated nodules (size; 3, 5, 8 and 10mm, density; -800, -630 and +100HU) were used for this study. The pacemaker was set on the anterior chest wall of phantom, and one simulated nodule was put in the lung field underneath the pacemaker. Then, Dual energy CT (Discovery CT750HD, GE healthcare) was performed, and five patterns of the virtual monochromatic images (40, 50, 65, 100 and 140KeV) were reconstructed with 5mm and 0.625mm slice thickness on the workstation. The same dual energy CT and the same reconstruction were performed for the chest phantom without simulated nodule. 260 series of virtual monochromatic images were obtained in total, and two independent observers assessed the metal artifact (3-point scale from 1; non to 3; severe) and the detection of the nodule (5-point scale from 1; definitely absent to 5; definitely present). The statistical analysis was performed with Wilcoxon signed rank test and Bonferroni correction for multiple comparisons, with p value of <0.01 (0.05/5). RESULTS In both 5mm and 0.625mm slice thickness, metallic artifact increased at 40 or 50KeV and decreased at 100 or 140KeV in comparison with that at 65KeV (p<0.01) (In 5mm slice thickness, the mean score was 3.0 ±0.0, 2.9±0.3, 2.3±0.5, 1.6±0.5, and 1.3±0.5 at 40, 50, 65, 100, and 140KeV. In 0.625mm slice thickness, the mean score was 3.0±0.2, 2.8±0.4, 2.4±0.5, 1.7±0.5, and 1.7±0.5 at 40, 50, 65, 100, and 140KeV). In 0.625 mm slice thickness, the detection score of the nodule was not statistically different between 65KeV and 40, 50, 100 or 140KeV (the mean score was 4.4±1.0, 4.5±1.0, 4.6±1.0, 4.5±1.1, and 4.4±1.2 at 40, 50, 65, 100, and 140KeV). However, the detection score of the nodule at 40KeV was significantly worse than that at 65 KeV (p<0.01) in 5 mm slice thickness (the mean score was 4.1±1.1, 4.3±1.1, 4.4±1.2, 4.3±1.4, and 4.3±1.2 at 40, 50, 65, 100, and 140KeV). CONCLUSION High KeV image can reduce metal artifact, but detection score of the nodule dose not change. Low KeV image increase metal artifact, and thick slice worsens the nodule detection. CLINICAL RELEVANCE/APPLICATION High KeV image is useful to reduce metal artifact. Low KeV image with thick slice is not suitable for nodule detection.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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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: PURPOSE To compare the iodine content of solitary lung cancer using gemstone spectral imaging with dynamic measurements of attenuation (Hounsfield Units, HU) and to correlate their quantitative CT data with expressions of vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) and hypoxia-inducible factor-1 (HIF-1) using immunostaining methods. METHOD AND MATERIALS Forty patients were scanned by dual-energy CT (Discovery CT750HD; GE) with fast kV (80- and 140-kVp) switching mode for examining solitary pulmonary nodules. Of them, 12 patients who were histopathologically confirmed as primary lung cancer were included. CT images were obtained before (plain scan) and after contrast material (IOHEXOL, Omnipaque™300) injection (1-minute-, 2-minute-, and 3-minute-delayed scans). The dose of contrast material per patient was decided on the basis of 2 ml per weight. Enhancement values (EV = [CT value at each delayed scan] - [CT value at plain scan]) were calculated by using a circular region of interest on a monitor. Iodine content (IC) at each delayed scan was measured in mg/cc from the iodine-water material decomposition pair on the advantage workstation. Immunostaining using VEGF, EGFR, and HIF-1 was performed by a pathologist, who evaluated the expression level of them on a 3- or 4-point scale according to the previously-reported criteria. RESULTS The dose and injection rate of contrast material were 115.5ml±15.3 (mean ± SD) and 1.9ml/s±0.3, respectively. EV at each delayed scan (1-minute-, 2-minute-, and 3-minute-delayed scans) was 60.9HU±26.4, 65.4HU±23.5, and 62.1HU±26.9, respectively. IC at each delayed scan was 2.62mg/cc ±1.33, 2.64mg/cc±0.95, and 2.58mg/cc±1.13, respectively. Positive correlations between EV and IC were found at 2-minute- and 3-minute-delayed scans (rank correlation test, r=0.75 and 0.60, respectively). There was a significant correlation between the expression level of HIF-1 (y) and IC at 2-minute-delayed scan (x) (p=0.03): regression equation, y=1.86 +0.49x. CONCLUSION Gemstone spectral imaging using dual-energy dynamic multiphase CT can offer iodine content in solitary lung cancer. Iodine content at 2-minute-delayed scan may correlate with the expression level of HIF-1. CLINICAL RELEVANCE/APPLICATION HIF-1 over-expression has been associated with aggressive tumor behavior and overall poor prognosis. Prognosis of lung cancer may be possibly predicted by iodine content at 2-minute-delayed scan.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE The purpose of this study was to evaluate intratumoral metabolic heterogeneity in gastrointestinal stromal tumor (GIST) and malignant lymphoma (ML) on F18-FDG PET to determine if the finding was helpful to discriminate these tumors. METHOD AND MATERIALS FDG PET/CT findings of 21 abdominal large tumors (> 5cm in major axis) were retrospectively evaluated before treatment (9 GISTs and 12 MLs). Intratumoral heterogeneity was evaluated by visual score (VS: 0, homogeneous; 1, slightly heterogeneous; 2, moderately heterogeneous; 3, highly heterogeneous) and adaptive thresholding method on the maximum transaxial PET image of the tumor. Tumor area ratios above 30, 50, and 70% of maximum of standardized uptake value (SUVmax) (TR30, TR50, and TR70, respectively) and numbers of isolated island areas above 30, 50, and 70% of SUVmax (N30, N50, and N70, respectively) were calculated. Correlation between VS and other parameters were also investigated by Spearman's rank test. RESULTS GISTs exhibited heterogeneous distribution of FDG with marginal dominant, whereas MLs showed rather homogeneous pattern on visual analysis (VS=2.67 ± 0.50 and 0.58 ± 0.79, respectively, p<0.001). SUVmax tended to be lower in GISTs than in MLs, although not statistically significant (7.4 ± 2.6 and 12.6 ± 6.0, respectively, p=0.065). TR30, TR50, and TR70 were significantly lower in GISTs than MLs (TR30: 0.67 ± 0.30 and 0.97 ± 0.07, p=0.002; TR50: 0.37 ± 0.22 and 0.81 ± 0.14, p<0.001; and TR70: 0.14 ± 0.09 and 0.48 ± 0.17, p<0.001, respectively), which supported visual results of heterogeneity in GISTs. N50 was significantly higher in GISTs than MLs (2.11 ± 0.93 and 1.08 ± 0.29, p=0.004). Significant correlations were observed between VS and adaptive thresholding parameters (TR30, TR50, TR70, N50, and N70) (ρ=-0.802, ρ=-0.847, ρ=-0.882, ρ=0.712, and ρ=0.445, respectively). CONCLUSION GISTs exhibited significantly heterogeneous intratumoral distribution as compared to MLs. Focusing on intratumoral heterogeneity as well as SUVmax may help to evaluate the entire characteristics of tumors. CLINICAL RELEVANCE/APPLICATION Focusing on intratumoral heterogeneity will present valuable additional information for PET/CT diagnosis in patients with large abdominal tumors.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: PURPOSE To evaluate the utility of the motion-artifact-reducing software for the dual-shot energy subtraction radiography on a direct conversion flat-panel detector system. METHOD AND MATERIALS 20 normal volunteers were included in this study. Two or three nodules (8 – 10 mm in diameter, CT attenuation value: +100HU) were attached to the surface of the chest in each volunteer, and energy subtraction radiography was performed. Dual energy soft tissue image and dual energy bone image were reconstructed with and without the motion-artifact-reducing software. The lung field was divided into 6 lung fields (right, left × upper, middle, lower), and 10 readers evaluated the chest radiograph, soft tissue image and bone image without the motion-artifact-reducing software. Those with the motion-artifact-reducing software were also evaluated one week later. The scores of the nodule detection were assigned from 0 (definitely normal) to 100 (definitely abnormal) by readers’ confidence in each lung field. The statistical analysis was performed by ROC (receiver operating characteristic) analysis and paired t-test. RESULTS There was no significant difference in the three left lung fields, the right upper and the right middle lung field between dual energy subtraction with the motion-artifact-reducing software and that without the software. However, dual energy subtraction with the motion-artifact-reducing software (Az value: 0.9136) was significant better than that without software (Az value: 0.8984) in the right lower lung field (p = 0.02). CONCLUSION The motion-artifact-reducing software was useful for the nodule detection in the right lower lung field on dual energy subtraction radiography of the volunteers. CLINICAL RELEVANCE/APPLICATION The motion-artifact-reducing software might have the potential to improve the nodule detection in the dual-shot energy subtraction radiography.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: PURPOSE To analyze quantitatively preoperative CT data of pathological stage I pulmonary adenocarcinomas using a custom-developed software and to correlate the results with prognostic factors. METHOD AND MATERIALS 145 adenocarcinomas with pathological stage I were entered into the present study. A custom-developed software can segment solid portion and ground-glass opacity (GGO) using the previously-reported threshold selection method for segmenting gray-level images, and can eliminate vessels on CT using 3-D multi-scale line filter for segmentation and visualization of curvilinear structures such as vessels, resulting in calculating a rate of pure solid portion volume to whole tumor volume (%Solid) regardless of distribution of solid portions in nodule. The following groupings due to %Solid are also possible with this software: pure GGO, dense GGO, part-solid with various distributions of solid portions, and pure solid. Inter-observer agreement between radiologist and software groupings was examined using weighted-Kappa test. Prognostic factors included lymphoduct invasion (LI), vascular invasion (VI), pleural invasion (PI), 5-year overall survival (OS), and 5-year disease-free survival (DFS). Immunostaining methods by D2-40 and CD31 were used for examining LI and VI, respectively. Survival curves were calculated according to the Kaplan-Meier method. Prognostic factors were analyzed by Logistic regression model and Cox proportional hazard model. RESULTS There was a good agreement between radiologist and software groupings (weighted kappa=0.760). Multivariate logistic regression analyses revealed that %Solid was significantly useful in estimating LI (p=0.038) and PI (p=0.008). Cox proportional hazard model revealed that %Solid significantly contributed to DFS (p=0.0003). If the cutoff value of %Solid is 63%, there was a significant difference between survival curve of %Solid≥63% (DFS rate, 68.1%) and that of %Solid<63% (DFS rate, 97.6%) (p<0.0001). CONCLUSION Three-dimensional %Solid of adenocarcinomas with pathological stage I is feasible for estimating lymphoduct invasion, pleural invasion, and 5-year disease-free survival. Nodule with %Solid≥63% significantly contributed to short disease-free survival. CLINICAL RELEVANCE/APPLICATION Quantitative CT analysis using the software might be able to provide results for estimating prognosis in pulmonary adenocarcinomas with pathological stage I.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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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: PURPOSE To compare the results of metabolic response defined in PET response criteria in solid tumors (PERCIST) and those of the response evaluation criteria in solid tumors (RECIST) based on the revised response criteria (RRC) for lymphoma, especially in patients (pts) with residual FDG uptake after treatment. METHOD AND MATERIALS Among lymphoma patients pts having FDG PET/CT exams before and after chemo- and/or radiotherapy during Apr 2007 and Sep 2009, 23 pts represented residual FDG uptake after treatment. These 23 pts were evaluated in this study, as we focused specially on the changes of quantitative parameters. Changes of peak standardized uptake value normalized to lean body mass (SULpeak) after treatment defined in PERCIST as well as those of SUVmax and tumor size were calculated and assessed based on the visual results of RRC. SULpeak was calculated from the 1.2cm-diameter 3D region-of-interest placed on the hottest lesion on PET. Tumor size was measured in the longest diameter on CT. Body weight ranged from 38 to 96 kg (mean 61 kg). RESULTS There were 15 pts with partial remission (PR), 2 with stable disease (SD), and 6 with progressive disease (PD) after treatment based on RRC. Of 15 PR pts, 14 and 13 showed partial response on PERCIST and RECIST, respectively. Both of 2 SD pts were correctly evaluated on PERCIST and RECIST. Of 5 PD pts without new lesions, 4 represented progression on PERCIST, while only one on RECIST. Overall, 21 (91%) on PERCIST and 17 (74%) on RECIST of 23 pts showed consistent results with RRC. Changes of SUVmax exhibited an excellent relationship with those of SULpeak (r=0.99) and were considered to provide consistent results with RRC in 21 pts. No relationship was observed between changes of SULpeak and tumor size. CONCLUSION PERCIST was demonstrated to be more accurate than RECIST in lymphoma pts with residual FDG uptake after treatment. However, no difference was observed in the evaluation between SULpeak and SUVmax in our patient population. CLINICAL RELEVANCE/APPLICATION PERCIST was demonstrated to be feasible and more accurate than RECIST in evaluating lymphoma after treatment.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010

Publication Stats

170 Citations
76.77 Total Impact Points

Institutions

  • 2014
    • Stanford Medicine
      Stanford, California, United States
  • 2007–2014
    • Osaka City University
      • Department of Radiology
      Ōsaka, Ōsaka, Japan
  • 2013
    • Osaka Rosai Hospital
      Ōsaka, Ōsaka, Japan