肺部氧通气成像的动物实验研究

The experimental study of oxygen contrast MR ventilation imaging

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 3 7% ,t=2 683 ,P <0 0 2 5 ) ;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 。

Objective To study the feasibility and basic technology of the oxygen contrast MR ventilation imaging in lung Methods Six canine lungs were scanned by using inversion recovery pulse sequence with turbo spin echo acquisition before and after inhalation of the 100% oxygen as T 1 contrast agent, and the T 1 values were measured The contrast to noise ratio(CNR) for each inversion recovery time was compared and the relationship between arterial blood oxygen pressure(PaO 2)and T 1 relaxation rate was observed Subtraction technique was employed in the postprocessing of pre and post oxygen conditions Results Molecular oxygen could shorten the pulmonary T 1 value(average 13 37%, t =2 683, P <0 025) The optimized inversion delay time for the best CNR was about the average between the T 1 value of pre and post oxygen conditions The relaxtivity of T 1 resulted in excellent linear correlation( r 2 = 0 997 4)with PaO 2 Through the subtraction of pre and post oxygen image, the oxygen contrast MR ventilation image was obtained Conclusion The oxygen contrast MR ventilation imaging has the feasibility and clinical potential for the assessment of regional pulmonary function