Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.
Respirology. 2012 Nov;17(8):1237-46. doi: 10.1111/j.1440-1843.2012.02250.x.
Spirometry is insensitive to small airway abnormalities in asthma. Our objective was to evaluate regional lung structure and function using hyperpolarized (3)He magnetic resonance imaging (MRI) before, during and after a methacholine challenge (MCh).
Twenty-five asthmatics (mean age = 34 ± 11 years) and eight healthy volunteers (HV) (mean age = 33 ± 11 years) underwent spirometry, plethysmography and hyperpolarized (3)He MRI prior to a MCh. MRI was repeated following the MCh and again 25 min after salbutamol administration. (3)He MRI gas distribution was quantified using semiautomated segmentation of the ventilation defect percent (VDP). Tissue microstructure was measured using the (3)He apparent diffusion coefficient (ADC). Analysis of variance with repeated measures was used to evaluate changes at each time point as well as to determine interactions between regions of interest (ROI) and subject group. Pearson's correlations were performed to evaluate associations between (3)He MRI measurements and established clinical measures.
In asthmatics, but not HV, whole-lung ADC was increased post-MCh (P < 0.01). In asthmatics only, ADC was increased post-MCh in posterior ROI (P < 0.01) and all ROI in the superior-inferior direction (P < 0.01). VDP was increased in posterior and inferior ROI (P < 0.001). There was a correlation between VDP and specific airway resistance (r = 0.74, P < 0.0001), dyspnoea score (r = 0.66, P < 0.01) and fractional exhaled nitric oxide (r = 0.45, P < 0.05).
We evaluated the regional pulmonary response to methacholine and salbutamol using (3)He MRI and showed heterogeneous VDP and ADC consistent with bronchoconstriction and gas trapping, respectively, post-MCh. These regional alterations resolved post-salbutamol.
在哮喘中，肺量计对小气道异常不敏感。我们的目的是在乙酰甲胆碱激发（MCh）前后使用超极化（3）氦磁共振成像（MRI）评估区域性肺结构和功能。
25 例哮喘患者（平均年龄=34±11 岁）和 8 例健康志愿者（HV）（平均年龄=33±11 岁）在 MCh 前进行了肺量计、体描法和超极化（3）氦 MRI。在 MCh 后和沙丁胺醇给药后 25 分钟再次重复 MRI。使用通气缺陷百分比（VDP）的半自动分割来量化（3）氦 MRI 气体分布。使用（3）氦表观扩散系数（ADC）测量组织微观结构。使用重复测量方差分析评估每个时间点的变化，并确定感兴趣区域（ROI）和研究对象组之间的相互作用。进行 Pearson 相关性分析以评估（3）氦 MRI 测量值与既定临床测量值之间的关联。
在哮喘患者中，但在 HV 中，全肺 ADC 在 MCh 后增加（P<0.01）。仅在哮喘患者中，MCh 后在后部 ROI 中 ADC 增加（P<0.01），并且在上下方向的所有 ROI 中 ADC 增加（P<0.01）。在后部和下部 ROI 中 VDP 增加（P<0.001）。VDP 与特定气道阻力（r=0.74，P<0.0001）、呼吸困难评分（r=0.66，P<0.01）和呼出的一氧化氮分数（r=0.45，P<0.05）之间存在相关性。
我们使用（3）氦 MRI 评估了对乙酰甲胆碱和沙丁胺醇的区域性肺反应，并显示了在 MCh 后与支气管收缩和气体捕获分别一致的不均匀 VDP 和 ADC。这些区域变化在沙丁胺醇后得到解决。
