Browsing by Author "Lee, J. -C."

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Evaluating Instantaneous Perfusion Responses of Parotid Glands to Gustatory Stimulation Using High-Temporal-Resolution Echo-Planar Diffusion-Weighted Imaging
(2016-10)
Chiu, T. -W.
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Liu, Y. -J.
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Chang, H. -C.
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Lee, Y. -H.
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Lee, J. -C.
BACKGROUND AND PURPOSE: Parotid glands secrete and empty saliva into the oral cavity rapidly after gustatory stimulation. However, the role of the temporal resolution of DWI in investigating parotid gland function remains uncertain. Our aim was to design a high-temporal-resolution echo-planar DWI pulse sequence and to evaluate the instantaneous MR perfusion responses of the parotid glands to gustatory stimulation. MATERIALS AND METHODS: This prospective study enrolled 21 healthy volunteers (M/F = 2:1; mean age, 45.2 12.9 years). All participants underwent echo-planar DWI (total scan time, 304 seconds; temporal resolution, 4 s/scan) on a 1.5T MR imaging scanner. T2WI (b = 0 s/mm(2)) and DWI (b = 200 s/mm(2)) were qualitatively assessed. Signal intensity of the parotid glands on T2WI, DWI, and ADC was quantitatively analyzed. One-way ANOVA with post hoc group comparisons with Bonferroni correction was used for statistical analysis. P < .05 was statistically significant. RESULTS: Almost perfect interobserver agreement was achieved ( 0.656). The parotid glands had magnetic susceptibility artifacts in 14.3% (3 of 21) of volunteers during swallowing on DWI but were free from perceptible artifacts at the baseline and at the end of scans on all images. Increased ADC and reduced signal intensity of the parotid glands on T2WI and DWI occurred immediately after oral administration of lemon juice. Maximal signal change of ADC (24.8% +/- 10.8%) was significantly higher than that of T2WI (-10.1% +/- 5.2%, P < .001). The recovery ratio of ADC (100.71% +/- 42.34%) was also significantly higher than that of T2WI (22.36% +/- 15.54%, P < .001). CONCLUSIONS: Instantaneous parotid perfusion responses to gustatory stimulation can be quantified by ADC by using high-temporal-resolution echo-planar DWI.
Scattering amplitudes for multi-indexed extensions of solvable potentials
(2014-04-01)
Ho, C. -L.
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Lee, J. -C.
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Sasaki, R.
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電子物理學系
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Department of Electrophysics
New solvable one-dimensional quantum mechanical scattering problems are presented. They are obtained from known solvable potentials by multiple Darboux transformations in terms of virtual and pseudo virtual wavefunctions. The same method applied to confining potentials, e.g. Poschl-Teller and the radial oscillator potentials, has generated the multi-indexed Jacobi and Laguerre polynomials. Simple multi-indexed formulas are derived for the transmission and reflection amplitudes of several solvable potentials. (C) 2014 Elsevier Inc. All rights reserved.