目的评价核素肺通气/灌注(V/Q)显像对不典型亚肺段肺栓塞(PE)的诊断价值。方法患者141例,男58例,女83例,年龄(65.67±11.29)岁,其中下肢静脉病变史者14例,糖尿病、高脂血症史者45例,63例近期内行有创性诊断和治疗,另19例均无上述病...目的评价核素肺通气/灌注(V/Q)显像对不典型亚肺段肺栓塞(PE)的诊断价值。方法患者141例,男58例,女83例,年龄(65.67±11.29)岁,其中下肢静脉病变史者14例,糖尿病、高脂血症史者45例,63例近期内行有创性诊断和治疗,另19例均无上述病史或诊疗史。所有患者行常规^(99)Tc^m-MAA 和^(99)Tc^m 气体显像后进行1～24个月的抗凝治疗,于治疗后再行肺灌注显像。将抗凝治疗前后肺灌注显像进行对比分析,根据肺内放射性分布的变化判断治疗效果,再结合临床资料及其他影像检查综合判断不典型 PE 的诊断。结果 141例患者肺灌注显像均显示某个肺野内不呈肺段或亚肺段分布的片状或小斑片状放射性分布稀疏区。肺通气显像示肺野内放射性分布基本均匀,未见放射性分布稀疏区。治疗后118例肺灌注显像显示双肺内放射性分布不同程度的增多或均匀。按肺野内放射性分布改善情况标准评价:抗凝治疗后恢复正常35例,显效49例,有效34例,总有效率为83.69%(118/141)。另23例肺内放射性分布无明显变化,视为无效。结论 V/Q 显像是诊断不典型亚肺段 PE 的首选方法。展开更多
A general theory of microperforated-panel absorbers is proposed on the basis of equhaleot circuits. The characterizing parameters of the absorber are its relative acoustic resistance γ, the diameter d of the perforat...A general theory of microperforated-panel absorbers is proposed on the basis of equhaleot circuits. The characterizing parameters of the absorber are its relative acoustic resistance γ, the diameter d of the perforations and the resonance frequency fo. The later two form the perforate constaot k = , which, together with γ, decides the structure and characteristics of the microperforated-panel absorber. The maximum value of the absorption band width △f/f0 is (4/π)tan-1(1＋γ), as k approaches zero, and it does not change much as far as k is less than 1, the cavity depth is nearly a quarter wavelength of the resonance frequency For large values of k, the absorption band narrows down significalltly and the cavity depth required becomes a small fraction of the wavelength. The general properties of the microperforated absorber are discussed.展开更多
文摘目的评价核素肺通气/灌注(V/Q)显像对不典型亚肺段肺栓塞(PE)的诊断价值。方法患者141例,男58例,女83例,年龄(65.67±11.29)岁,其中下肢静脉病变史者14例,糖尿病、高脂血症史者45例,63例近期内行有创性诊断和治疗,另19例均无上述病史或诊疗史。所有患者行常规^(99)Tc^m-MAA 和^(99)Tc^m 气体显像后进行1～24个月的抗凝治疗,于治疗后再行肺灌注显像。将抗凝治疗前后肺灌注显像进行对比分析,根据肺内放射性分布的变化判断治疗效果,再结合临床资料及其他影像检查综合判断不典型 PE 的诊断。结果 141例患者肺灌注显像均显示某个肺野内不呈肺段或亚肺段分布的片状或小斑片状放射性分布稀疏区。肺通气显像示肺野内放射性分布基本均匀,未见放射性分布稀疏区。治疗后118例肺灌注显像显示双肺内放射性分布不同程度的增多或均匀。按肺野内放射性分布改善情况标准评价:抗凝治疗后恢复正常35例,显效49例,有效34例,总有效率为83.69%(118/141)。另23例肺内放射性分布无明显变化,视为无效。结论 V/Q 显像是诊断不典型亚肺段 PE 的首选方法。
文摘A general theory of microperforated-panel absorbers is proposed on the basis of equhaleot circuits. The characterizing parameters of the absorber are its relative acoustic resistance γ, the diameter d of the perforations and the resonance frequency fo. The later two form the perforate constaot k = , which, together with γ, decides the structure and characteristics of the microperforated-panel absorber. The maximum value of the absorption band width △f/f0 is (4/π)tan-1(1＋γ), as k approaches zero, and it does not change much as far as k is less than 1, the cavity depth is nearly a quarter wavelength of the resonance frequency For large values of k, the absorption band narrows down significalltly and the cavity depth required becomes a small fraction of the wavelength. The general properties of the microperforated absorber are discussed.
