Image synthesis of monoenergetic CT image in dual-energy CT using kilovoltage CT with deep convolutional generative adversarial networks

Purpose: To synthesize a dual-energy computed tomography (DECT) image from an equivalent kilovoltage computed tomography (kV-CT) image using a deep convolutional adversarial network. Methods: A total of 18,084 images of 28 patients are categorized into training and test datasets. Monoenergetic CT images at 40, 70, and 140 keV and equivalent kVCT images at 120 kVp are reconstructed via DECT and are defined as the reference images. An image prediction framework is created to generate monoenergetic computed tomography (CT) images from kV-CT images. The accuracy of the images generated by the CNN model is determined by evaluating the mean absolute error (MAE), mean square error (MSE), relative root mean square error (RMSE), peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and mutual information between the synthesized and reference monochromatic CT images. Moreover, the pixel values between the synthetic and reference images are measured and compared using a manually drawn region of interest (ROI). Results: The difference in the monoenergetic CT numbers of the ROIs between the synthetic and reference monoenergetic CT images is within the standard deviation values. The MAE, MSE, RMSE, and SSIM are the smallest for the image conversion of 120 kVp to 140 keV. The PSNR is the smallest and the MI is the largest for the synthetic 70 keV image. Conclusions: The proposed model can act as a suitable alternative to the existing methods for the reconstruction of monoenergetic CT images in DECT from single-energy CT images

Cardiac and skeletal muscle abnormality in taurine transporter-knockout mice

Taurine, a sulfur-containing β-amino acid, is highly contained in heart and skeletal muscle. Taurine has a variety of biological actions, such as ion movement, calcium handling and cytoprotection in the cardiac and skeletal muscles. Meanwhile, taurine deficiency leads various pathologies, including dilated cardiomyopathy, in cat and fox. However, the essential role of taurine depletion on pathogenesis has not been fully clarified. To address the physiological role of taurine in mammalian tissues, taurine transporter-(TauT-) knockout models were recently generated. TauTKO mice exhibited loss of body weight, abnormal cardiac function and the reduced exercise capacity with tissue taurine depletion. In this chapter, we summarize pathological profile and histological feature of heart and skeletal muscle in TauTKO mice

Pathologic significance of immunoglobulin G4-positive plasma cells in extrahepatic cholangiocarcinoma.

13301甲第3920号博士（医学）金沢大学博士論文要旨Abstract 要約Outline 以下に掲載：Human Pathology 43(12) pp.2149-2156 2012. ELSEVIER. 共著者：Yasushi Kimura, Kenichi Harada, Yasuni Nakanum

Pathologic significance of immunoglobulin G4-positive plasma cells in extrahepatic cholangiocarcinoma

Immunoglobulin G4-related sclerosing cholangitis is histologically characterized by the infiltration of immunoglobulin G4-positive plasma cells and sclerosing change. Moreover, several cases of carcinoma accompanied by immunoglobulin G4-positive cells in tissue and increased serum immunoglobulin G4 levels have been reported, but the association between cancer-associated immunity and an immunoglobulin G4 reaction is still unclear. In this study, we examined the infiltration of immunoglobulin G4-positive cells in extrahepatic cholangiocarcinoma and the pathologic significance of the immunoglobulin G4 reaction found in cancer tissues in terms of the evasion of immune surveillance by regulatory T cells. Immunohistochemistry for immunoglobulin G4, forkhead box P3, CD4, and CD8 was performed using 68 surgical specimens from patients with extrahepatic cholangiocarcinoma, and positive cells were investigated, particularly within and around cancerous tissues. Consequently, although immunoglobulin G4+ cells were few (average, <10 cells/high-power field) in most cases, 10 or more and 50 or more cells were found in 37% and 6% of cases, respectively. Immunoglobulin G4+ cells were predominantly found in the invasive front of carcinoma tissue. In the cases with 10 or more immunoglobulin G4+ cells, forkhead box P3+ regulatory T cells were also distinguishable, and a positive correlation was found between the forkhead box P3+/CD4+ ratio and immunoglobulin G4+ cell count, but few CD8+ cells invaded cancer cells (<10 cells). In conclusion, extrahepatic cholangiocarcinomas are often accompanied by the significant infiltration of immunoglobulin G4+ cells, and the immunoglobulin G4 reaction showed a positive and negative correlation with forkhead box P3+ and CD8+ cells, respectively, suggesting the evasion of immune surveillance associated with CD8+ cytotoxic T cells via the regulatory function of forkhead box P3+ regulatory T cells. © 2012 Elsevier Inc. All rights reserved

Functional Differentiation of Memory Retrieval Network in Macaque Posterior Parietal Cortex

SummaryHuman fMRI studies revealed involvement of the posterior parietal cortex (PPC) during memory retrieval. However, corresponding memory-related regions in macaque PPC have not been established. In this monkey fMRI study, comparisons of cortical activity during correct recognition of previously seen items and rejection of unseen items revealed two major PPC activation sites that were differentially characterized by a serial probe recognition paradigm: area PG/PGOp in inferior parietal lobule, along with the hippocampus, was more active for initial item retrieval, while area PEa/DIP in intraparietal sulcus was for the last item. Effective connectivity analyses revealed that connectivity from hippocampus to PG/PGOp, but not to PEa/DIP, increased during initial item retrieval. The two parietal areas with differential serial probe recognition profiles were embedded in two different subnetworks of the brain-wide retrieval-related regions. These functional dissociations in the macaque PPC imply the functional correspondence of retrieval-related PPC networks in macaques and humans

Assessment of biological dosimetric margin for stereotactic body radiation therapy

Purpose: To develop a novel biological dosimetric margin (BDM) and to create a biological conversion factor (BCF) that compensates for the difference between physical dosimetric margin (PDM) and BDM, which provides a novel scheme of a direct estimation of the BDM from the physical dose (PD) distribution. Methods: The offset to isocenter was applied in 1‐mm steps along left‐right (LR), anterior‐posterior (AP), and cranio‐caudal (CC) directions for 10 treatment plans of lung stereotactic body radiation therapy (SBRT) with a prescribed dose of 48 Gy. These plans were recalculated to biological equivalent dose (BED) by the linearquadratic model for the dose per fraction (DPF) of d = 3–20 Gy/fr and α/β= 3 - 10. BDM and PDM were defined so that the region that satisfied that the dose covering 95% (or 98%) of the clinical target volume was greater than or equal to the 90% of the prescribed PD and BED, respectively. An empirical formula of the BCF was created as a function of the DPF. Results: There was no significant difference between LR and AP directions for neither the PDM nor BDM. On the other hand, BDM and PDM in the CC direction were significantly larger than in the other directions. BCFs of D95% and D98% were derived for the transverse (LR and AP) and longitudinal (CC) directions. Conclusions: A novel scheme to directly estimate the BDM using the BCF was developed. This technique is expected to enable the BED‐based SBRT treatment planning using PD‐based treatment planning systems

Synthesized effective atomic numbers for commercially available dual-energy CT

Purpose: The objective of this study was to assess synthesized effective atomic number (Zeff) values with a new developed tissue characteristic phantom and contrast material of varying iodine concentrations using single-source fast kilovoltage switching dual-energy CT (DECT) scanner. Methods: A newly developed multi energy tissue characterisation CT phantom and an acrylic phantom with various iodine concentrations of were scanned using single-source fast kilovoltage switching DECT (GE-DECT) scanner. The difference between the measured and theoretical values of Zeff were evaluated. Additionally, the difference and coefficient of variation (CV) values of the theoretical and measured values were compared with values obtained with the Canon-DECT scanner that was analysed in our previous study. Results: The average Zeff difference in the Multi-energy phantom was within 4.5%. The average difference of the theoretical and measured Zeff values for the acrylic phantom with variation of iodine concentration was within 3.3%. Compared to the results for the single-source Canon-DECT scanner used in our previous study, the average difference and CV of the theoretical and measured Zeff values obtained with the GE-DECT scanner were markedly smaller. Conclusions: The accuracy of the synthesized Zeff values with GE-DECT had a good agreement with the theoretical Zeff values for the Multi-Energy phantom. The GE-DECT could reduce the noise and the accuracy of the Zeff values than that with Canon-DECT for the varying iodine concentrations of contrast medium. Advances in knowledge: The accuracy and precision of the Zeff values of the contrast medium with the GE-DECT could be sufficient with human equivalent materials