Development of lung function diagnosis using hyperpolarized Xenon gas

本研究旨在利用超极化129核素MRI对肺功能进行诊断。主要研究对象是精确的肺解剖图像和换气功能图像。通过对肺组织和血液中129氚气体的解析，分析肺换气功能。首先在动物MRI系统上建立了超极化129氚的肺部成像，然后准备了适合129氚的特定肺部线圈在人体MRI系统上的试验。即使能获得人肺超极化129的光谱，对肺成像也是相当困难的。我们的氙偏振度可能不够高。另一个可能的原因是气体本身的扩散常数太大。梯度磁场对扩散示踪剂的核磁共振信号进行了衰减。数学模型模拟和实验结果表明，梯度磁场的大小对磁感应强度的降低有一定的影响.为了解决这个问题，我们现在准备了新的序列程序与频率调制的RF脉冲。初步的研究对高信噪比的遥感图像有一定的帮助。我们实验室的伦理审查委员会已经批准了超极化129的人肺MRI。通过本研究建立了实验方案。

This research is for lung function diagnostic using hyperpolarized 129Xe MRI. Precise anatomical lung image and images of exchange gas function is main object. Exchange gas function in lung is analyzed by resolved 129Xe gas to lung tissue and blood. Lung image with hyperpolarized 129Xe in animal MRI system was established at first, then trials in human MRI system with specific lung coil suited to 129Xe was prepared. Even a spectrum of hyperpolarized 129Xe from human lung was able to be acquired, it was quite difficult for lung image. Our xenon polarization may not be high enough for image. Another possible reason why we cannot get lung image is large diffusion constant in gas itself. Gradient magnetic field for imaging is reduced the NMR signal in diffusible tracer. Mathematical model simulation and our experiment show a reduction related a magnitude of gradient magnetic field. For solve this problem, we now prepared the new sequence program with frequency modulated RF pulses. It should be helpful for high S/N image as far as our preliminary study. Ethic review committee in our laboratory is already approved the human lung MRI with hyperpolarized 129Xe. The experiment protocol has been established through this research.