目的:探讨3.0 T磁共振(MR)多片技术双反转恢复(MS-DIR)序列在膝关节滑膜病变诊断中的价值。方法:选取福建中医药大学附属第二人民医院2018年6月至2021年6月期间收治的100例膝关节滑膜病变患者作为研究对象,均接受3.0 T MRMS-DIR序列和...目的:探讨3.0 T磁共振(MR)多片技术双反转恢复(MS-DIR)序列在膝关节滑膜病变诊断中的价值。方法:选取福建中医药大学附属第二人民医院2018年6月至2021年6月期间收治的100例膝关节滑膜病变患者作为研究对象,均接受3.0 T MRMS-DIR序列和脂肪抑制T1增强(T1WI-FS-CE)序列检查,以T1WI-FS-CE为金标准,分析MS-DIR诊断膝关节滑膜病变类型与T1WI-FS-CE诊断结果的一致性并进行图像评分。结果:T1WI-FS-CE和MS-DIR序列诊断膝关节滑膜病变类型的Kappa值为0.797;MS-DIR序列图像整体质量、图像均匀度、滑膜细节和T1WI-FS-CE序列比较,差异无统计学意义(P>0.05)。结论:MS-DIR和T1WI-FS-CE序列诊断膝关节滑膜病变类型一致性好,准确度高,且与T1WI-FS-CE序列图像评分相当。展开更多
The determination of the precise thickness-shear frequency of electroded crystal plates has practical importance in quartz crystal resonator design and fabricatiom especially when the high fundamental thickness-shear ...The determination of the precise thickness-shear frequency of electroded crystal plates has practical importance in quartz crystal resonator design and fabricatiom especially when the high fundamental thickness-shear frequency has reduced the crystal plate thickness to such a degree that proper consideration of the effect of electrodes is very important. The electrodes effect as mass loading in the estimation of the resonance frequency has to be modified to consider the stiffness of electrodes, as the relative strength is increasingly noticeable. By following a known procedure in the determination of the thickness-shear frequency of an infinite AT-cut crystal plate, frequency equations of crystal plate without and with piezoelectric effect are obtained in terms of elastic constants and the electrode material density. After solving these equations for the usual design parameters of crystal resonators, the design process can be optimized to pinpoint the precise configuration to avoid time-consuming trial and reduction steps. Since these equations and solutions are presented for widely used materials and parameters, they can be easily integrated into the existing crystal resonator design and manufacturing processes.展开更多
文摘目的:探讨3.0 T磁共振(MR)多片技术双反转恢复(MS-DIR)序列在膝关节滑膜病变诊断中的价值。方法:选取福建中医药大学附属第二人民医院2018年6月至2021年6月期间收治的100例膝关节滑膜病变患者作为研究对象,均接受3.0 T MRMS-DIR序列和脂肪抑制T1增强(T1WI-FS-CE)序列检查,以T1WI-FS-CE为金标准,分析MS-DIR诊断膝关节滑膜病变类型与T1WI-FS-CE诊断结果的一致性并进行图像评分。结果:T1WI-FS-CE和MS-DIR序列诊断膝关节滑膜病变类型的Kappa值为0.797;MS-DIR序列图像整体质量、图像均匀度、滑膜细节和T1WI-FS-CE序列比较,差异无统计学意义(P>0.05)。结论:MS-DIR和T1WI-FS-CE序列诊断膝关节滑膜病变类型一致性好,准确度高,且与T1WI-FS-CE序列图像评分相当。
基金Project supported by the Qianjiang River Fellow Fund of ZhejiangProvince, and Bureau of Personnel and Human Resource, Ningbo,China
文摘The determination of the precise thickness-shear frequency of electroded crystal plates has practical importance in quartz crystal resonator design and fabricatiom especially when the high fundamental thickness-shear frequency has reduced the crystal plate thickness to such a degree that proper consideration of the effect of electrodes is very important. The electrodes effect as mass loading in the estimation of the resonance frequency has to be modified to consider the stiffness of electrodes, as the relative strength is increasingly noticeable. By following a known procedure in the determination of the thickness-shear frequency of an infinite AT-cut crystal plate, frequency equations of crystal plate without and with piezoelectric effect are obtained in terms of elastic constants and the electrode material density. After solving these equations for the usual design parameters of crystal resonators, the design process can be optimized to pinpoint the precise configuration to avoid time-consuming trial and reduction steps. Since these equations and solutions are presented for widely used materials and parameters, they can be easily integrated into the existing crystal resonator design and manufacturing processes.
