Ba ckground The a sse ssment of regional pulmonary ventilation and perfusion is e ssential for theevaluation of a variety of lung disorders1 Pulmonary ventilation MRI using inhaled oxygen a s a contra stmedium can be obtained with a clinical MR scanner, without additional equipment, and ha s beendemonstrated to be a fea sible means of a sse ssing ventilation in animal models and some clinical patient s1However, few studie s have reported on MR ventilation-perfusion imaging1 In this study, we evaluated theusefulne ss of oxygen-enhanced ventilation in combination with first-pa ss Gd-DTPA-enhanced perfusion MRIin a canine model of pulmonary embolism and airway obstruction1Met h o ds Peripheral pulmonary embolisms were produced in eight dogs by intravenous injection of gelfoamstrip s at the pulmonary segmental arterial level, and airway obstructions were created in five of the dogs byinserting a self-de signed balloon catheter into asecondary bronchus1 Oxygen-enhanced MR ventilationimages were produced by subtracting images from before and after inhalation of pure oxygen1 Pulmonaryperfusion MR images were acquired with a dynamic three-dimensional fast gradient2echo sequence1 MRventilation and perfusion image swere read and contra sted with re sult s from general examinations ofpathological anatomy, ventilation2perfusion scintigraphy, and pulmonary angiography Results Regions identified as having airway obstructions matched using both MR ventilation and perfusionimaging, but regions of pulmonary embolisms were mismatched1 The area of airway obstruction defect swa s smaller using MR ventilation imagery than that using ventilation scintigraphy1 Abnormal perfusionregions due to pulmonary embolisms were divided into defective regions and reduced regions ba sed on thetime course of signal intensity change s1 In the diagno sis of pulmonary embolisms with the technique ofventilation and perfusion MRI, sensitivity and specificity were 75.0% and 98.1%, re spectively, and thediagno stic re sult s of this MRI technique were in agreement with the results of ventilation-perfusionscintigraphy and pulmonary angiography (K: 01899, 01743) Conclusions Oxygen-enhanced ventilation in combination with pulmonary perfusion MRI can be used todiagno se abnormalitie s of airways and blood ve ssels in the lungs, and can provide regional functionalinformation with high spatial and temporal re solution1 This method possesses great potential value forclinical applications1

目的 探讨氧对比通气MR肺部成像的可行性和基本技术方法。方法 采用医用纯氧作为T1WI肺通气对比剂，运用反转恢复超快速自旋回波序列，对6只犬进行扫描。测量和比较吸氧前后的肺组织T1值；改变反转恢复时间，观察氧增强对比度噪声比的变化；吸入不同浓度的氧气，观察动脉血氧分压和肺组织纵向弛豫率的关系；采用图像减影技术进行后处理。结果 吸入氧气可以缩短肺组织的T1值（平均13.37%, t=2.683, P<0.025）；最佳反转恢复时间为吸氧前、后T1值的均数,此时可得到最优的对比度噪声比；外周动脉血氧分压和肺组织纵向弛豫率呈直线相关（r2=0.9974）；通过吸氧前后的图像减影可获得氧对比的肺通气功能图。结论 氧对比通气成像简便易行，能反映肺的局部通气功能，具有潜在的临床应用价值。

AIM: To cxplore the diagnostic effect of pulmonary ventilation-perfnsionfMRI for pulmonary embolism(PE).METMODS: Gelatin sponge was intraduced into the left fewer lobar pal-monary arteries of 4 dogs through catheter under distal subtraction an#ag-raphy(DSA) so as to establish PE model. Before PE, the dogs inhaled roomair(21%O2) and 99.5%02 respectively and inhaled 99.5% 02 again afterPE. Then MRI scanning was performed for pulmonatT ventilation. The signalintersitites (SI) of left lower lobe wore meesured and its variation was oh-sexved. The dogs were undergone MRI scanning before and efiex PE to ob-serve the perfusion of ]eft lower lobe.RESULTS: Both before and ofter PE the SI of left lower lobe after inhalationof 99.5% O2 increased significantly much more than after inhalation of indoorair. However, there was no significant difference in the increase of SI valuehctween the emhollc left lower lobe and non-mhdiio region of the right lowerlobe (t=3.685, P>0.05), indicating that pulmonary ventilation was notinfluenced in the emholic region of left lower loho. During perfusion MRscanning and after injection of contrast media, the SI of non-embelic re#on inthe fight lower lobe rapidly inched and reached the peak 6.8 aconds atinrinjection of contrast media. Bm the time-signal intensity curve of die embeficregion of left fower lube rpmained at lower level and had no apparont peakvalue all the time. CONCLUSION: Oxygen-enhanced ventilation fMRI combining pexlnsionfMRI provide a new diagnostic means for PE. The method is feasible andbeneficial for PE diagnosis.

目的 探讨相位对比法MRI测量中心肺动脉各血管的血流速度和血流量的准确性以及临床应用价值。方法　正常健康志愿者21例，采用相位对比法MRI测量中心肺动脉，包括主肺动脉、右肺动脉、左肺动脉、右肺上叶动脉、右肺叶间动脉和左肺叶间动脉各血管的直径、一个心动周期的最大血流速度、平均速度和瞬时流量，并计算出各血管一个心动周期的血流量。结果 ①中心肺动脉各血管的直径分别为（24.5±3.4）mm、（16.9±2.6）mm、（16.3±1.8）mm、（6.1±1.3）mm、（12.0±1.6）mm和（11.3±1.4）mm。②中心肺动脉各血管的最大血流速度分别为（79.9±24.0）cm/s、78.7±20.2）cm/s、（77.4±22.1）cm/s、（66.1±9.2）cm/s、73.5±19.6）cm/s和（72.1±16.4）cm/s。③中心肺动脉各血管的平均速度分别为（50.3±7.7）cm/s、（49.9±11.0）cm /s、46.6±9.7）cm/s、（38.9 ±8.9）cm/s、（44.4±7.7）cm/s和（43.0±8.2）cm/s。④中心肺动脉各血管一个心动周期的血流量分别为（73.6 ±6.6）ml、（38.9±4.5）ml、（33.7±3.2）ml、（12.7 ±5.9）ml、（29.0±10.9）ml和（19.9±7.0）ml。⑤中心肺动脉的直径和血流量的对应点分布比较集中，呈现出直线上升的趋势，可以虚拟出高度相关的回归直线和直线相关方程，即Y=3.06X-7.04，相关系数r=0.90（P<0.001）。结论 相位对比法MRI可以准确测量中心肺动脉的血流速度和血流量，为无创性肺动脉血流动力学的研究奠定基础。

目的 评价FDG-PET对孤立性肺结节的临床诊断价值。方法 检索Cochrane图书馆、PubMed、OVID数据库，对纳入文献评估后，进行Meta分析，绘制SROC曲线，计算曲线下面积。最后进行敏感性分析。结果 Meta分析汇总的敏感性、特异性、阳性预测值、阴性预测值分别为93%、78%、90%、85%，SROC曲线下面积为93.19%。与病理诊断的结果符合率达90.21%。结论 FDG2PET是一种敏感性较高的诊断孤立性肺结节的非侵入性检查方法。但是特异性较低是其缺点。