Development of lung function diagnosis using hyperpolarized Xenon gas

本研究采用超极化129Xe MRI诊断肺功能。精确解剖肺图像和交换气体功能图像是主要目标。通过解析129Xe气体到肺组织和血液，分析肺内气体交换功能。首先在动物MRI系统上建立了超极化129Xe的肺图像，然后准备了适合129Xe的特定肺圈在人体MRI系统上的试验。即使能够获得人体肺部的超偏振129Xe光谱，但对肺部成像却相当困难。我们的氙气偏振度可能不够高，无法成像。我们无法获得肺部图像的另一个可能原因是气体本身的扩散常数很大。梯度磁场成像对扩散示踪剂中的核磁共振信号进行了减弱。数学模型仿真和实验结果表明，梯度磁场的大小有相应的减小。为了解决这个问题，我们编写了新的频率调制射频脉冲序列程序。通过初步的研究，对高信噪比图像有一定的帮助。我们实验室伦理审查委员会已经批准了人类肺部MRI超极化129Xe。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.