Risk Analysis of Breast Cancer by Using Bilateral Mammographic Density Differences: A Case-Control Study.

The identification of risk factors helps radiologists assess the risk of breast cancer. Quantitative factors such as age and mammographic density are established risk factors for breast cancer. Asymmetric breast findings are frequently encountered during diagnostic mammography.

Accuracy of virtual non-contrast images with different algorithms in dual-energy computed tomography.

We investigated the accuracy of the computed tomography (CT) numbers of virtual non-contrast (VNC) images for two different material decomposition algorithms using the same image data for different diluted contrast agent concentrations. A container filled with contrast agents was inserted into a cylindrical phantom and scanned with dual-energy protocols (80/Sn140 kV, 100/Sn140 kV) using a dual-source CT. VNC images were generated by the 2-material decomposition (MD) algorithm using the energy of each tube voltage and the linear attenuation coefficient, calculated from the theoretical spectral curve of the agent and the CT number of the image, respectively.

Accuracy of virtual monochromatic images generated by the decomposition of photoelectric absorption and Compton scatter in dual-energy computed tomography.

The decomposition of the linear attenuation coefficient into photoelectric absorption and Compton scattering provides virtual monochromatic images (VMIs). The accuracy of the computed tomography (CT) number of VMI, which is obtained by decomposing the linear attenuation coefficient into photoelectric absorption and Compton scattering, was verified in the energy range of 40-200 keV. The possibility of improving the accuracy of CT numbers by using pre-energy-calibrated images as input was also investigated.

Accuracy of spectral curves at different phantom sizes and iodine concentrations using dual-source dual-energy computed tomography.

To validate the accuracy of spectral curves obtained by an image-data-based algorithm and clarify the error factors that reduce accuracy. Iodine rods of known composition and different concentrations were inserted into a cylinder or elliptic-cylinder phantom and scanned according to the dual-energy protocol. Spectral curves were obtained by (i) theoretical calculation, (ii) image-data-based 2-material decomposition, and (iii) using a dedicated workstation.

Method to calculate frequency characteristics of reconstruction filter kernel in X-ray computed tomography.

A computed tomography (CT) image is generally reconstructed by a filtered back projection (FBP) algorithm. In an FBP algorithm, the image quality primarily depends on a reconstruction filter kernel. Although the details of the filter kernel are not disclosed to users, the frequency response of the filter kernel can theoretically be calculated using the relational formula of the filter kernel and the modulation transfer function (MTF) of the reconstruction algorithm (MTF).

Estimation and validation of the frequency responses of a scanner system and an image reconstruction system in X-ray computed tomography.

In computed tomography, factors that theoretically affect the modulation transfer function (MTF) in the region near the isocenter are the frequency responses of the scanner system (MTF) and reconstruction processing (MTF). Although MTF and MTF are performance indices that are not disclosed to the users, both can be estimated by the measured MTF with the use of theoretical formulas. In this study, we proposed two methods to obtain the MTF and MTF, and confirm their validity.

[Relationship between Quantitativeness of Iodine and Accuracy of Virtual Non-contrast Image in Dual-energy Computed Tomography].

Dual-energy computed tomography (DE-CT) is the promising technology, such as enabling material decomposition, generation of the virtual monochromatic image, and measurement of effective atomic numbers. There are reports that utilization of the virtual non-contrast (VNC) image, the iodine map image, and the virtual monochromatic image can contribute to the improvement of lesion detection and its characterization, compared with conventional contrast CT by single-energy computed tomography (SE-CT). In addition, acquisition of the VNC images makes it possible to skip scanning of true non-contrast CT, which is also expected to reduce exposure.

Evaluating clinical implications of 15-mega-sub-pixel liquid-crystal display in phase-contrast mammography.

Background: Phase-contrast mammography (PCM) systems characteristically yield sharp images with edge enhancement and high-resolution 25-μm/pixel mammograms. However, not all PCM image information can be shown on the display at a resolution of 5-megapixel (5-MP), although 5-MP monitors are recommended for interpretation of digital mammograms. Therefore, we investigated the potential utility of a 15-mega-sub-pixel (15-MsP) display for PCM images.

Six-year follow-up in skeletal Class III patient aged over 40 receiving orthognathic surgery and autotransplantation: a case report.

This paper describes the post-operative course of care in a patient requiring orthognathic surgery for skeletal mandibular protrusion in whom autotransplantation of a third molar was performed. A lower third molar that had to be removed for sagittal split ramus osteotomy (SSRO) was transplanted to replace the missing right second molar during pre-surgical orthodontic treatment, contributing to post-treatment occlusal stability. A 44-year-old woman presented with mandibular protrusion.

Oral flora in independent over 80-year-olds with more than 20 teeth.

The purpose of this study was to investigate oral flora in independent persons aged over 80 years with more than 20 remaining teeth. The subjects were 22 participants of the 8020 campaign (6 males and 16 females) with a mean age of 81.3+/-1.