超极化Xenon对慢阻肺的可视化加权成像（英文）

Visualize Diffusion Map of COPD Rat with Hyperpolarized Xenon MRI

超极化气体3He或者129Xe扩散加权成像已经被证明了能够有效检测慢性阻塞性肺部疾病(COPD)中肺部微结构的改变.相比于3He,129Xe更便宜而且更容易获得,但是129Xe成像中较低的信噪比致使129Xe的肺部表面扩散系数(ADC)的测量面临着许多困难.在该研究中,为了得到更高的图像信噪比,作者对气球模型,健康大鼠和COPD大鼠进行了单个b值(14 cm2/s)的扩散加权超极化129Xe磁共振成像(MRI).所有的COPD模型大鼠是通过烟熏和注射内毒素(LPS)进行诱导得到的.在7 T磁共振成像仪上面获得了大鼠肺实质的超极化129Xe ADC值分布图.COPD大鼠肺实质的129Xe ADC值是0.044 22±0.002 9和0.042 34±0.002 3 cm2/s(Δ=0.8/1.2 ms),远大于健康大鼠肺实质的129Xe ADC值0.037 7±0.002 3和0.036 7±0.001 3 cm2/s.而且COPD大鼠肺实质相关的129Xe ADC直方图也表现出了一定的展宽.这些结果说明了COPD大鼠肺泡空腔的增大能够通过129Xe在肺里面的ADC增长和相关直方图的拓宽反应出来,从而证明了单个b值的扩散加权MRI方法可以有效地对COPD大鼠进行检测.

Hyperpolarized3He or129Xe diffusion MRI has been demonstrated as a promising technique for the detection of microanatomical changes in chronic obstructive pulmonary disease （COPD）. Compared with 3He,129Xe is more available for the potential clinical applications. However, the measurement of129Xe apparent diffusion coefficient （ADC） possesses more challenges due to the relevant low gyromagnetic ratio and spin polarization. In this present study, a singleb value （b = 14 s/cm2） diffusion-weighted hyperpolarized129Xe MRI sequence was used to image a balloon phantom, healthy rats, and the COPD rats, respectively. All COPD rats were induced by second-hand smoke and lipopolysaccharide （LPS）. The lung129XeADCmaps were obtained on a 7 T MRI scanner. The mean lung parenchymal129XeADCswere 0.044 22±0.002 9 and 0.042 34±0.002 3 cm2/s （Δ = 0.8/1.2 ms） for the COPD rats, which showed significant increasements in comparison with healthy ones （0.037 7±0.002 3 and 0.036 7±0.001 3 cm2/s）. Furthermore, the correspondingADChistogram of the COPD rats exhibited a broader distribution as compared with the healthy ones. Our experiments demonstrated that the alveolar airspace enlargement in the COPD rats are able to be quantitatively evaluated by hyperpolarized xenon diffusion-weighted MRI.