Kohei Hayashida

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The purpose of this study was to develop a reliable and practical strategy that generates quantitative CBF and OEF maps accurately from PET data sets obtained with 15O-tracers. Sequential sinogram data sets were acquired after the administration of 15O-tracers, and combined single-frame images were obtained. The delay time between sampled input function and(More)
A new method has been developed for diffusible tracers, to quantify CBF at rest and after pharmacological stress from a single session of dynamic scans with dual bolus administration of a radiotracer. The calculation process consisted of three steps, including the procedures of incorporating background radioactivity contaminated from the previous scan.(More)
BACKGROUND AND PURPOSE Whether misery perfusion (MP) commonly accompanies brain borderzones (BZs) in patients with major cerebral artery occlusion remains unclear. We elucidated topographic patterns of chronic hemodynamic failure in such patients. METHODS Twenty-four patients with unilateral occlusion or severe stenosis (>75% in diameter) of the internal(More)
OBJECTIVE The purpose of this study was to determine whether pretreatment quantitative and visual parameters seen on PET/CT using (18)F-FDG add prognostic information for clinical staging in patients with head and neck cancer. MATERIALS AND METHODS We enrolled 108 patients with histologically proven oral, oropharyngeal, hypopharyngeal, and laryngeal(More)
Information on the distance to the target is very important to achieve the practical use of hands-free speech interfaces and nursing-care robots. Many distance measurement methods, which use the time-of-flight (TOF) of a reflected wave measured with reference to the transmitted wave, have been proposed. However, these methods cannot measure short distances(More)
The accuracy of the acetazolamide (ACZ) challenge test using semiquantitative SPECT in detecting Stage II hemodynamic failure, i.e. cerebral misery perfusion, in patients so diagnosed with PET has yet to be determined. This study was carried out in 53 patients who had a unilateral occlusion or severe stenosis of their cerebral artery. Asymmetry index (AI)(More)
Desired/undesired speech discrimination is as important as speech/non-speech discrimination to achieve useful applications such as speech interfaces and teleconferencing systems. Conventional methods of voice activity detection (VAD) utilize the directional information of sound sources to distinguish desired from undesired speech. However, these methods(More)
—Conventional near-field talker localization methods with microphone-array calculate spatial spectrum in each scanning position of discretized space and each frequency. Hence, elapsed time is increased and real-time processing is difficult. Real-time processing is important for achieving the natural interaction with the speech interfaces. To overcome this(More)
Many conventional security systems use visual information from a video camera. However, these systems may not be able to acquire the important scenes in the blind area of the video camera. Acoustic security systems can support conventional visual security systems with acoustic events detection. In our research, we focused on acoustic security systems in the(More)