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Peng Pengfei,Yue Xun,Tang Lu,Wu Xi,Deng Qiao,Wu Tao,Cai Lei,Liu Qi,Xu Jian,Huang Xiaoqi,Chen Yucheng,Diao Kaiyue,Sun Jiayu 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.12
Objective: To clinically validate the feasibility and accuracy of cine images acquired through the multitasking method, with no electrocardiogram gating and free-breathing, in measuring left ventricular (LV) function indices by comparing them with those acquired through the balanced steady-state free precession (bSSFP) method, with multiple breath-holds and electrocardiogram gating. Materials and Methods: Forty-three healthy volunteers (female:male, 30:13; mean age, 23.1 ± 2.3 years) and 36 patients requiring an assessment of LV function for various clinical indications (female:male, 22:14; 57.8 ± 11.3 years) were enrolled in this prospective study. Each participant underwent cardiac magnetic resonance imaging (MRI) using the multiple breath-hold bSSFP method and free-breathing multitasking method. LV function parameters were measured for both MRI methods. Image quality was assessed through subjective image quality scores (1 to 5) and calculation of the contrast-to-noise ratio (CNR) between the myocardium and blood pool. Differences between the two MRI methods were analyzed using the Bland–Altman plot, paired t-test, or Wilcoxon signed-rank test, as appropriate. Results: LV ejection fraction (LVEF) was not significantly different between the two MRI methods (P = 0.222 in healthy volunteers and P = 0.343 in patients). LV end-diastolic mass was slightly overestimated with multitasking in both healthy volunteers (multitasking vs. bSSFP, 60.5 ± 10.7 g vs. 58.0 ± 10.4 g, respectively; P < 0.001) and patients (69.4 ± 18.1 g vs. 66.8 ± 18.0 g, respectively; P = 0.003). Acceptable and comparable image quality was achieved for both MRI methods (multitasking vs. bSSFP, 4.5 ± 0.7 vs. 4.6 ± 0.6, respectively; P = 0.203). The CNR between the myocardium and blood pool showed no significant differences between the two MRI methods (18.89 ± 6.65 vs. 18.19 ± 5.83, respectively; P = 0.480). Conclusion: Multitasking-derived cine images obtained without electrocardiogram gating and breath-holding achieved similar image quality and accurate quantification of LVEF in healthy volunteers and patients.
Finite Element Analysis and Optimization of Dither Mechanism in Dithered Ring Laser Gyroscope
Xu-dong Yu,Guo Wei,Xing-wu Long,Jian-xun Tang 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
This paper presents an optimal structural design of dither mechanism in dithered ring laser gyroscope (DRLG) using finite element analysis (FEA). We establish an approximate theoretical model of the dithering mechanism to calculate resonant frequency and adopt the modal analysis and dynamics analysis to search the optimal solution. The validity and efficiency of the FEA are conformed by comparing with the sinusoidal and random vibration experimental results. An optimal dither mechanism is fabricated and measured experimentally. The results demonstrate the good vibration-isolated performance for the optimal design.