Jong Bae Park

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A novel ungated spiral phase-contrast (USPC) imaging method was developed for rapid measurement of time-averaged blood-flow rates in the presence of pulsatility. The spatial point-spread function was analyzed to provide an intuitive understanding of how spiral trajectories, which sample the k-space origin at every excitation, can mitigate the effects of(More)
PURPOSE To verify the potential of ungated spiral phase-contrast (USPC), which has been shown to provide accurate and reproducible time-averaged measurements of pulsatile flow, for rapid measurement of renal artery blood flow (RABF) in vivo. MATERIALS AND METHODS The RABF rates of 11 normal human subjects and one patient with renal failure were measured(More)
An ungated spiral phase-contrast (USPC) method was used to measure cardiac output (CO) rapidly and conveniently. The USPC method, which was originally designed for small peripheral vessels, was modified to assess CO by measuring flow in the ascending aorta (AA). The modified USPC used a 12-interleaf spiral trajectory to acquire full-image data every 283 ms(More)
3D (kx, ky, t)-space analysis is invoked to provide insights into dynamic magnetic resonance imaging (DMRI) with arbitrary k-space sampling trajectories. The effects of 3D sampling in (kx, ky, t) are analyzed theoretically and verified with computer simulation. The analyses show that a 3D sampling pattern that is more isotropic in (kx, ky, t)-space and(More)
We report a new method to produce ordered arrays of metal nanostructures on substrates. The method employs a through-hole nanoporous alumina membrane as a mask that is attached onto the substrate, silicon in this study. The material of deposition, Au in this study, was provided by pulsed laser ablation of a target gold. At an early stage of the deposition,(More)
Boundary violation is a common process in optimization problems. This problem can be seen in Particle Swarm Optimization(PSO) and its variants too. An aging based variant of PSO called, PSO with Aging Leader and Challengers(ALC-PSO) overcomes the stagnation problem that existed in PSO. To avoid the problem of random particles, some bound handling mechanisms(More)
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