Applied Clinical Study on Hyperpolarized Noble Gas MRI/MRS using Pathologic Model Animal

自制的极化装置经过改造，可连续供应极化至3- 5%的Xe气体流。在麻醉和自主呼吸下对小鼠施加极化氢气，并对肺和脑进行MRI和MRS测量。结果如下：1.在小鼠肺组织的~（129）MRS实验中，发现~（129）MRS自旋从肺组织溶解状态向肺泡气体状态的反向扩散影响洗脱曲线的斜率。通过饱和溶解的自旋来消除这种影响，从而测量洗脱曲线的真实斜率。2.将影响洗脱曲线斜率的因素分为三项，即脉冲角、通气量和表观弛豫时间。3.对小鼠脑组织中的洗脱曲线进行了精确的分析，得到了脑组织中的真实弛豫时间值。4.对VILI（Ventilator Induced Lung Injury）小鼠肺洗脱曲线的斜率进行了分析。与健康小鼠相比，VILI小鼠的斜率被发现延迟，表明病理肺中的通气缓慢。

Home-built polarizing apparatus has been modified to supply continuous flow of Xe gas polarized to 3-5%. The polarized Xe gas was applied to mice under anesthesia and spontaneous respiration, and MRI and MRS measurements were performed with lung and brain. The results are summarized as follows :1.In the Xe-129 MRS experiments with mice lungs, diffusion of Xe spins backward from the dissolved state in lung tissue to alveolar gas state was found to affect the slope in washout curve. The true slope of the washout curve was measured by removing this effect by saturating the dissolved spins.2.The factors affecting the slope of the washout curve was separated into three terms, which afforded pulse angle, ventilation volume, and apparent relaxation time. The separation of the true relaxation term and the perfusion term is now underway.3.Precise analysis of the washout curve in mouse brain was performed and the value of true relaxation time in brain tissue was obtained.4.The slope in the lung washout curve was analyzed with the VILI(Ventilator Induced Lung Injury) mice. The slope was found to be retarded with the VILI mice compared with the healthy ones, suggesting slow ventilation in the pathologic lungs.