Psychophysical evaluation of calibration curve for diagnostic LCD monitor

取得学位 : 博士（保健学）, 学位授与番号 : 医博甲第1866号 , 学位授与年月日 : 平成19年3月22日, 学位授与大学 : 金沢大学, 審査結果の報告日 : 平成19年2月14日, 主査 :真田 茂 , 副査 :鈴木 正行, 越田 吉

Psychophysical evaluation of calibration curve for diagnostic LCD monitor

金沢大学大学院医学系研究科量子医療技術学Purpose. In 1998, Digital Imaging Communications in Medicine (DICOM) proposed a calibration tool, the grayscale standard display function (GSDF), to obtain output consistency of radiographs. To our knowledge, there have been no previous reports of investigating the relation between perceptual linearity and detectability on a calibration curve. Materials and methods. To determine a suitable calibration curve for diagnostic liquid crystal display (LCD) monitors, the GSDF and Commission Internationale de l\u27Eclairage (CIE) curves were compared using psychophysical gradient δ and receiver operating characteristic (ROC) analysis for clinical images. Results. We succeeded in expressing visually recognized contrast directly using δ instead of the just noticeable difference (JND) index of the DICOM standard. As a result, we found that the visually recognized contrast at low luminance areas on the LCD monitor calibrated by the CIE curve is higher than that calibrated by the GSDF curve. On the ROC analysis, there was no significant difference in tumor detectability between GSDF and CIE curves for clinical thoracic images. However, the area parameter Az of the CIE curve is superior to that of the GSDF curve. The detectability of tumor shadows in the thoracic region on clinical images using the CIE curve was superior to that using the GSDF curve owing to the high absolute value of δ in the low luminance range. Conclusion. We conclude that the CIE curve is the most suitable tool for calibrating diagnostic LCD monitors, rather than the GSDF curve. © Japan Radiological Society 2006

Risk stratification for the prognosis of patients with chemoresistant urothelial cancer treated with pembrolizumab

The use of immune checkpoint inhibitors to treat urothelial carcinoma (UC) is increasing rapidly without clear guidance for validated risk stratification. This multicenter retrospective study collected clinicopathological information on 463 patients, and 11 predefined variables were analyzed to develop a multivariate model predicting overall survival (OS). The model was validated using an independent dataset of 292 patients. Patient characteristics and outcomes were well balanced between the discovery and validation cohorts, which had median OS times of 10.2 and 12.5 mo, respectively. The final validated multivariate model was defined by risk scores based on the hazard ratios (HRs) of independent prognostic factors including performance status, site of metastasis, hemoglobin levels, and the neutrophil-to-lymphocyte ratio. The median OS times (95% confidence intervals [CIs]) for the low-, intermediate-, and high-risk groups (discovery cohort) were not yet reached (NYR) (NYR–19.1), 6.8 mo (5.8-8.9), and 2.3 mo (1.2-2.6), respectively. The HRs (95% CI) for OS in the low- and intermediate-risk groups vs the high-risk group were 0.07 (0.04-0.11) and 0.23 (0.15-0.37), respectively. The objective response rates for in the low-, intermediate-, and high-risk groups were 48.3%, 28.8%, and 10.5%, respectively. These differential outcomes were well reproduced in the validation cohort and in patients who received pembrolizumab after perioperative or first-line chemotherapy (N = 584). In conclusion, the present study developed and validated a simple prognostic model predicting the oncological outcomes of pembrolizumab-treated patients with chemoresistant UC. The model provides useful information for external validation, patient counseling, and clinical trial design

Second nationwide surveillance of bacterial pathogens in patients with acute uncomplicated cystitis conducted by Japanese Surveillance Committee from 2015 to 2016: antimicrobial susceptibility of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus saprophyticus

The Japanese Surveillance Committee conducted a second nationwide surveillance of antimicrobial susceptibility patterns of uropathogens responsible for acute uncomplicated cystitis (AUC) in premenopausal patients aged 16–40 years old at 31 hospitals throughout Japan from March 2015 to February 2016. In this study, the susceptibility of causative bacteria (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus) for various antimicrobial agents was investigated by isolation and culturing of organisms obtained from urine samples. In total, 324 strains were isolated from 361 patients, including E. coli (n = 220, 67.9%), S. saprophyticus (n = 36, 11.1%), and K. pneumoniae (n = 7, 2.2%). The minimum inhibitory concentrations (MICs) of 20 antibacterial agents for these strains were determined according to the Clinical and Laboratory Standards Institute (CLSI) manual. At least 93% of the E. coli isolates showed susceptibility to fluoroquinolones and cephalosporins, whereas 100% of the S. saprophyticus isolates showed susceptibility to fluoroquinolones and aminoglycosides. The proportions of fluoroquinolone-resistant and extended-spectrum β-lactamase (ESBL)-producing E. coli strains were 6.4% (13/220) and 4.1% (9/220), respectively. The antimicrobial susceptibility of K. pneumoniae was retained during the surveillance period, while no multidrug-resistant strains were identified. In summary, antimicrobial susceptibility results of our second nationwide surveillance did not differ significantly from those of the first surveillance. Especially the numbers of fluoroquinolone-resistant and ESBL-producing E. coli strains were not increased in premenopausal patients with AUC in Japan

Stimulatory effect of hydrothermally synthesized biodegradable hydroxyapatite granules on osteogenesis and direct association with osteoclasts.

Calcium-deficient hydroxyapatite (HA) granules with a unique spherical shape were prepared using an applied hydrothermal method. Spherical stoichiometric HA granules were also prepared by normal sintering and both granules were used for implantation into rat tibiae to compare the biological responses to each implant. Twelve and 24 weeks after implantation, the volume of calcium-deficient HA granules was significantly less than that of stoichiometric HA granules, and the biodegradability of calcium-deficient HA granules was confirmed. The larger number of osteoclasts, larger osteoblast surface and larger bone volume in the implanted area of calcium-deficient HA than those of stoichiometric HA suggested that osteoclastic resorption of calcium-deficient HA affected osteogenesis in that area. To analyze the direct contribution of osteoclasts to osteogenesis, C2C12 multipotent myoblastic cells, which have the potential to differentiate into osteoblasts in the presence of bone morphogenetic protein 2, were cultured with supernatants of osteoclasts cultured on calcium-deficient HA, stoichiometric HA, beta-tricalcium phosphate disks or plastic dishes, or bone marrow macrophages cultured on plastic dishes. Supernatants of osteoclasts but not bone marrow macrophages stimulated the expression of Runx2 and osteocalcin in C2C12 cells in concert with bone morphogenetic protein 2. The expression of alkaline phosphatase was stimulated with supernatants of osteoclasts cultured on ceramic disks. These results suggested that osteoclasts produced certain soluble factors which stimulated osteoblastic differentiation and they were thought to be associated with the induction of a larger osteoblast surface and bone volume in the animals implanted with calcium-deficient HA granules

Internal electric field influence on tunneling anisotropic magnetoresistance in epitaxial ferromagnet/n-GaAs junctions

A strong voltage-dependent tunneling anisotropic magnetoresistance (TAMR) effect was observed in a fully epitaxial Co2MnSi/n-GaAs junction and a Co50Fe50/n-GaAs junction. Angular dependence of the tunnel resistance showed uniaxial-type anisotropic tunnel resistance between the [110] and [11ˉ0] directions in the (001) plane. The voltage at which the TAMR effect was suppressed was close to that at which the differential conductance reached a minimum in both samples, suggesting that the strength and/or the sign of the internal electric field at the Co2MnSi/n-GaAs and Co50Fe50/n-GaAs junctions could be related to the voltage-dependent TAMR effect through spin-orbit interaction

Suppression of in-plane tunneling anisotropic magnetoresistance effect in Co2MnSi/MgO/n-GaAs and CoFe/MgO/n-GaAs junctions by inserting a MgO barrier

The effects of MgO tunnel barriers on both junction resistance and tunneling anisotropic magnetoresistance (TAMR) characteristics of Co2MnSi(CMS)/MgO/n-GaAs junctions and Co50Fe50(CoFe)/MgO/n-GaAs junctions were investigated. The resistance-area (RA) product of the CMS/MgO/n-GaAs junctions showed an exponential dependence on MgO thickness (t_[MgO]), indicating that the MgO layer acts as a tunneling barrier. The RA product of CMS/MgO/n-GaAs with t_[MgO] < 1 nm was smaller than that of the sample without MgO. The observed spin-valvelike magnetoresistance of CMS/n-GaAs and CoFe/n-GaAs Schottky tunnel junctions attributed to the TAMR effect did not appear in the cases of CMS/MgO/n-GaAs and CoFe/MgO/n-GaAs tunnel junctions. The lowering of the RA product and the suppression of the TAMR effect caused by inserting a thin MgO layer between CMS and n-GaAs were both possibly due to suppression of the Fermi-level pinning of GaAs and lowering of the Schottky barrier height

Influence of GaAs surface structure on tunneling anisotropic magnetoresistance and magnetocrystalline anisotropy in epitaxial Co50Fe50/n-GaAs junctions

An epitaxial Co50Fe50 layer was grown on As-terminated or Ga-terminated GaAs, and the influence of the termination species on both uniaxial-type tunneling anisotropic magnetoresistance (TAMR) characteristics and magnetocrystalline anisotropy was investigated. The magnetocrystalline anisotropy induced in the Co50Fe50 thin film was strongly dependent on the termination species of the GaAs surface, while the TAMR characteristics were almost unchanged. These experimental findings suggest that the TAMR effect is due to the anisotropy of electronic structure rather than the structural anisotropy