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Purpose: We compared stair-step artifacts and radiation dose between prospective electrocardiography (ECG)-gated coronary computed tomography angiography (prospective CCTA) and retrospective CCTA using 64-detector CT and determined the optimal padding time (PT) for prospective CCTA.Materials and Methods: We retrospectively evaluated 183 patients [mean heart rate (HR) <65 beats/min, maximum HR instability <5 beats/min] who had undergone CCTA. We scored stair-step artifacts from 1 (severe) to 5 (none) and evaluated the effective dose in 53 patients with retrospective CCTA and 130 with prospective CCTA (PT 200 ms, n = 32; PT 50 ms, n = 98).Results: Mean artifact scores were 4.3 in both retrospective and prospective CCTAs. However, statistically more arteries scored <3 (nonassessable) on prospective CCTA (P < 0.001). Mean scores for prospective CCTA with 200- and 50-ms PT were 4.1 and 4.3, respectively (no significant difference). The radiation dose of prospective CCTA was reduced by 59.1% to 80.7%.Conclusion: Prospective CCTA reduces the radiation dose and allows diagnostic imaging in most cases but shows more nonevaluable artifacts than retrospective CCTA. Use of 50-ms instead of 200-ms PT appears to maintain image quality in patients with a mean HR < 65 beats/min and HR instability of <5 beats/min. [ABSTRACT FROM AUTHOR]

Myocardial imaging with gallium-67 citrate was used to detect myocarditis in 46 consecutive infants and children (31 boys and 15 girls, mean age 21 months) with Kawasaki disease. In all of them planar imaging (group A) was performed at 6 hours and at 48 or 72 hours after the intravenous administration of a mean (SD) dose of gallium-67 citrate (0.07 (0.02) mCi/kg). Thirty four patients (24 boys and 10 girls, mean age 21 months) also had single photon emission computed tomography imaging (group B) soon after planar imaging. The patients had been ill for from 5 days to 16 days (mean (SD) 10.5 (2.4) days in group A and 10.6 (3.0) days in group B). The colour images obtained at 48 or 72 hours were positive in 41% of group A and in 64% of group B. Among the patients with clinically suspected myocarditis, 63% in group A and 80% in group B had positive myocardial images. Single photon emission computed tomography imaging permitted the identification of tracer in the myocardium, the pericardium only, or in the heart chambers. Myocardial imaging with gallium-67 citrate, especially when used with single photon emission computed tomography imaging, is useful for the detection of myocarditis in the acute phase of Kawasaki disease. [ABSTRACT FROM PUBLISHER]

We investigated a new class of coupled granular/continuous (CGC) perpendicular media consisting of CoCrPt-SiO2 granular layer with magnetically decoupled small grains. By changing the number of Co/Pd bi-layers in the continuous layer, the degree of exchange coupling can be systematically controlled. The introduction of Co/Pd multilayer improved the nucleation field (Hn) from -570 to -1670 Oe and KuV/κB T values from 67 to 97. Compared to the base granular media, the CGC media had 1 dB gain in signal-to-noise ratio (SNR) as well as 14 dB gain in write-ability (OW). Moreover, the output decay was reduced from -0.11 to -0.035 dB per decade. In CGC approach, a more appropriate strength of exchange coupling can be introduced that yields the significant improvement in both SNR and thermal stability. [ABSTRACT FROM AUTHOR]

Explores the Josephson coupling in a-axis sandwich-type superconductor/normal/superconductor junctions. Optimization of the growth parameters and characterization of the films; Dependence of the transport material on the doping; Correlation of the coupling strength of the barrier with the conductivity of the barrier material.