MR肺通气联合灌注成像的动物模型研究

目的 探讨氧增强MR肺通气成像联合肺灌注成像诊断气道阻塞和肺栓塞(PE)病变的可行性和价值。方法 对8只犬通过肺段动脉水平注入凝胶海绵颗粒复制周围型PE模型，其中5只经自制球囊导管插入二级气道又建立气道阻塞模型。通过吸纯氧前后的图像减影可获得氧增强MR肺通气图像。利用对比剂首次通过法可进行MR肺灌注成像。观察MR肺通气和灌注成像的表现，并与大体病理解剖、核素肺通气-灌注成像和肺血管造影进行对照。结果 MR肺通气和灌注成像在气道阻塞区的表现相匹配，但在肺栓塞区不匹配。气道阻塞区在MR肺通气成像中的缺损区域小于核素肺通气成像。根据信号强度随时间变化曲线，肺灌注异常区可分为灌注缺损和减低区。MR肺通气联合灌注成像诊断肺栓塞的敏感度和特异度分别为75．0％和98．1％；其诊断结果与核素肺通气一灌注成像和肺血管造影的一致性较好(K=0．743、0．899)。结论 氧增强MR肺通气成像联合肺灌注成像可用来诊断肺内气道和血管异常，该方法与核素肺通气-灌注成像类似，并能提供量化的功能信息和更高的时间、空间分辨率，具有临床应用价值。

MR-based assessment of pulmonary ventilation-perfusion in animal models

Objective To show the feasibility and value in the diagnosis of airway obstruction and pulmonary embolism with MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging. Methods Eight canines were implemented for peripheral pulmonary embolism by intravenous injection of gelfoam granules at pulmonary segmental arterial level, and five of them were formed airway obstruction models by inserting self-made balloon catheter at second-bronchia. The oxygen-enhanced MR ventilation imaging was introduced by subtracting the images of pre- and post- inhaled pure oxygen. The MR pulmonary perfusion imaging was achieved by the first-pass contrast agent method. Moreover, the manifestation of MR ventilation and perfusion imaging was observed and contradistinguished with that of general pathologic anatomy, ventilation-perfusion scintigraphy, and pulmonary angiography. Results The manifestations of airway obstruction regions in MR ventilation and perfusion imaging were matched, but those of pulmonary embolism regions were dismatched. The defect range of airway obstruction in MR ventilation image was smaller than that in ventilation scintigraphy. The abnormal perfusion regions of pulmonary embolism were divided into defect regions and reduce regions based on the time courses of signal intensity changes. The sensitivity and specificity of diagnosis on pulmonary embolism by MR ventilation combined with perfusion technique were 75.0% and 98.1%. The diagnostic results were in good coherence with ventilation-perfusion scintigraphy and pulmonary angiography(K=0.743, 0.899). Conclusion The MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging can be used to diagnose the airway and vascular abnormity in lung. This technique resembles the ventilation-perfusion scintigraphy. It can provide quantitative functional information and better spatial and temporal resolution, and possesses the value of clinical application.