Browsing by Author "Chiu, T. -W."

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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.
;
Lee, Y. -H.
;
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.
Fully integrated bio-chip with high sensitivity for electrochemical sensing application
(2019-04-18)
Chen, W. -H.
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Chang, C. -H.
;
Shih, H. -Y.
;
Chiu, T. -W.
;
Kuo, C. -N.
This Letter presents a fully integrated bio-system with the property of high sensitivity for electrochemical detection, which can intrinsically measure electrochemical characteristics with cyclic voltammetry. In normal circumstances, ultra-low electrolytes exist in tissue solution, which is difficult to accurately detect the oxidation/reduction signals, limited by the innate circuit and liquid noise. Hence, the conventional topology of the potentiostat circuit is improved and proposed in this Letter to remove the required analogue-to-digital converter (ADC). The overall operational mechanism of the potentiostat behaves like a single-slope ADC, which achieves a compact, easily implemented, and low-noise design. Additionally, the effective capacitance of potentiostat and liquid resistance make an RC integration to further suppress out-of-band noise, thereby enabling the low-electrolyte detection and improving detecting sensitivity. To simulate the low-electrolyte environment, only 0.01 M (M = mol/l) phosphate buffered saline background solution is used and required to demonstrate its feasibility of the concept. The measured results show the sensor chip with high sensitivity to sense resistive variation of electrochemical action in low electrolytes.