Imaging Research Laboratories, Robarts Research Institute, 100 Perth Dr, London, ON, Canada N6A 5K8.
Radiology. 2012 Nov;265(2):600-10. doi: 10.1148/radiol.12120485. Epub 2012 Sep 5.
To quantitatively compare hyperpolarized helium 3 (3He) and xenon 129 (129Xe) magnetic resonance (MR) images obtained within 5 minutes in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD) and to evaluate the correlations between 3He and 129Xe MR imaging measurements and those from spirometry and plethysmography.
This study was approved by an ethics board and compliant with HIPAA. Written informed consent was obtained from all subjects. Eight healthy volunteers and 10 patients with COPD underwent MR imaging, spirometry, and plethysmography. Ventilation defect percentages (VDPs) at 3He and 129Xe imaging were obtained by using semiautomated segmentation. Apparent diffusion coefficients (ADCs) were calculated from 3He (b=1.6 sec/cm2) and 129Xe (b=12 sec/cm2) diffusion-weighted images. VDPs at hyperpolarized 3He and 129Xe imaging were compared with a two-tailed Wilcoxon signed rank test and analysis of variance; Pearson correlation coefficients were used to evaluate the relationships among measurements.
129Xe VDP was significantly greater than 3He VDP for patients with COPD (P<.0001) but not for healthy volunteers (P=.35), although 3He and 129Xe VDPs showed a significant correlation for all subjects (r=0.91, P<.0001). The forced expiratory volume in 1 second (FEV1) showed a similar and significant correlation with 3He VDP (r=-0.84, P<.0001) and 129Xe VDP (r=-0.89, P<.0001), although the correlation between the FEV1/forced vital capacity (FVC) ratio and 129Xe VDP (r=-0.95, P<.0001) was significantly greater (P=.01) than that for FEV1/FVC and 3He VDP (r=-0.84, P<.0001). A significant correlation was also observed for 3He and 129Xe ADC (r=0.97, P<.0001); 129Xe ADC was significantly correlated with diffusing capacity of lung for carbon monoxide (r=-0.79, P=.03) and computed tomographic emphysema measurements (areas with attenuation values in the 15th percentile: r=-0.91, P=.0003; relative areas with attenuation values of less than -950 HU: r=0.87, P=.001).
In patients with COPD, the VDP obtained with hyperpolarized 29Xe MR imaging was significantly greater than that with 3He MR imaging, suggesting incomplete or delayed filling of lung regions that may be related to the different properties of 129Xe gas and physiologic and/or anatomic abnormalities in COPD.
定量比较健康志愿者和慢性阻塞性肺疾病（COPD）患者在 5 分钟内获得的超极化氦 3（3He）和氙 129（129Xe）磁共振（MR）图像，并评估 3He 和 129Xe MR 成像测量值与肺活量计和体积描记法测量值之间的相关性。
本研究获得伦理委员会批准并符合 HIPAA 规定。所有受试者均签署书面知情同意书。8 名健康志愿者和 10 名 COPD 患者接受了 MR 成像、肺活量计和体积描记法检查。使用半自动分割法获得 3He 和 129Xe 成像的通气缺陷百分比（VDP）。从 3He（b=1.6 sec/cm2）和 129Xe（b=12 sec/cm2）扩散加权图像计算表观扩散系数（ADC）。采用双尾 Wilcoxon 符号秩检验和方差分析比较超极化 3He 和 129Xe 成像的 VDP；采用 Pearson 相关系数评估各测量值之间的关系。
COPD 患者的 129Xe VDP 明显大于 3He VDP（P<.0001），但健康志愿者之间无显著差异（P=.35），尽管所有受试者的 3He 和 129Xe VDP 均呈显著相关性（r=0.91，P<.0001）。第 1 秒用力呼气量（FEV1）与 3He VDP（r=-0.84，P<.0001）和 129Xe VDP（r=-0.89，P<.0001）也呈相似且显著的相关性，尽管 FEV1/用力肺活量（FVC）比值与 129Xe VDP（r=-0.95，P<.0001）的相关性明显大于 FEV1/FVC 和 3He VDP（r=-0.84，P<.0001）（P=.01）。3He 和 129Xe ADC 也呈显著相关性（r=0.97，P<.0001）；129Xe ADC 与一氧化碳弥散量（r=-0.79，P=.03）和 CT 肺气肿测量值（衰减值位于第 15 百分位的区域：r=-0.91，P=.0003；衰减值小于-950 HU 的相对区域：r=0.87，P=.001）呈显著相关性。
在 COPD 患者中，超极化 129Xe MR 成像获得的 VDP 明显大于 3He MR 成像，提示肺区可能存在不完全或延迟填充，这可能与 129Xe 气体的不同特性以及 COPD 的生理和/或解剖异常有关。
