Medical Imaging and Information Sciences

Recently, malware or computer viruses have been used in espionage aimed at governments and companies. These threats usually arrive as email attachments of specially crafted document files such as Microsoft Word files, Power Point files, Ichitaro files, and PDF files. Those files are crafted to exploit vulnerabilities exists in those applications to install malware on victim machines. One of the major types of malware installed on those attacks is backdoor trojan aiming to operate infected machines and steal information stored in machines. This paper introduces general characteristics of malware and attacks used in espionage.

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In this paper, we propose a registration method for cardiac CT and SPECT. There are fewer correlations between CT and SPECT. Hence it is difficult to register CT to SPECT directly by referencing pixel values. Consequently we propose 2-step registration method using model data which is called “Atlas data". Atlas data has two kinds of information, the first one is normalized SPECT data which is made by averaging some of patient's SPECT. The other is cardiac anatomical data. They include a long and short axes of left ventricle. In the first step of 2-step registration, CT and atlas data are aligned. User needs to set up the axis that is the same as that of atlas data. When it is set, the alignment problem of CT and atlas is solved easily because it just transforms CT axes onto atlas axes. In the second step of the registration, atlas data is aligned to SPECT. In this step, we use general registration method that uses correlation coefficient as metric, and rigid transformation as transformation. Through these steps, CT images are registered to SPECT images via atlas. All case of experimental registration worked well for diagnosis of ischemic heart disease.

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The purpose of our study is to develop and to assess a method to calculate T₁ and T₂ relaxation times using fast spin-echo (FSE) sequences with two echoes per excitation. On a 1.5-T MRI, dual-echo FSE sequences with different repetition times (TR:TR₂=2TR₁, i.e., TR₁=400ms and TR₂=800ms) were performed in MnCl₂ phantom. Then, we assessed effects of the echo train length (ETL) , effective echo time (TE) , and T₂ correction for T₁ measurement, when changed each imaging parameter. Besides, we evaluated with comparison between the dual-echo FSE method and mixed sequence. With optimizing FSE imaging parameters, i.e., effective TE, TR, and low ETL, the measurement values of T₁ and T₂ revealed significantly higher correlation between the dual FSE method and mixed sequence. Moreover, the T₂ correction to calculate T₁ value could be omitted by shortening first effective TE. The dual-echo FSE method makes it possible to measure T₁ and T₂ fast and easily and to obtain more detailed information of organizations in human.

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