Diaz Sandra, Casselbrant Ingrid, Piitulainen Eeva, Pettersson Goran, Magnusson Peter, Peterson Barry, Wollmer Per, Leander Peter, Ekberg Olle, Akeson Per
Department of Radiology, Malmö University Hospital, Malmö, Sweden.
J Magn Reson Imaging. 2008 Apr;27(4):763-70. doi: 10.1002/jmri.21212.
To measure the apparent diffusion coefficient (ADC) of hyperpolarized (HP) (3)He gas using diffusion weighted MRI in healthy volunteers and patients with emphysema and examine the reproducibility and volume dependency.
A total of eight healthy volunteers and 16 patients with emphysema were examined after inhalation of HP (3)He gas mixed with nitrogen (N(2)) during breathhold starting from functional residual capacity (FRC) in supine position. Coronal diffusion-sensitized MR images were acquired. Each subject was imaged on three separate days over a seven-day period and received two different volumes (6% and 15% of total lung capacity [TLC]) of HP (3)He each day. ADC maps and histograms were calculated. The mean and standard deviation (SD) of the ADC at different days and volumes were compared.
The reproducibility of the mean ADC and SD over several days was good in both healthy volunteers and patients (SD range of 0.003-0.013 cm(2)/second and 0.001-0.009 cm(2)/second at 6% and 15% of TLC for healthy volunteers, and a SD range of 0.001-0.041 cm(2)/second and 0.001-0.011 cm(2)/second, respectively, for patients). A minor but significant increase in mean ADC with increased inhaled gas volume was observed in both groups.
Mean ADC and SD of HP (3)He MRI is reproducible and discriminates well between healthy controls and patients with emphysema at the higher gas volume. This method is robust and may be useful to gain new insights into the pathophysiology and course of emphysema.
使用扩散加权磁共振成像（MRI）测量健康志愿者和肺气肿患者中超极化（HP）（3）氦气的表观扩散系数（ADC），并检查其可重复性和体积依赖性。
共有8名健康志愿者和16名肺气肿患者，在仰卧位从功能残气量（FRC）开始屏气期间吸入与氮气（N₂）混合的HP（3）氦气后接受检查。采集冠状位扩散敏感MR图像。每位受试者在7天内分三天进行成像，每天接受两种不同体积（总肺容量[TLC]的6%和15%）的HP（3）氦气。计算ADC图和直方图。比较不同日期和体积下ADC的平均值和标准差（SD）。
健康志愿者和患者在数天内平均ADC和SD的可重复性均良好（健康志愿者在TLC的6%和15%时，SD范围分别为0.003 - 0.013 cm²/秒和0.001 - 0.009 cm²/秒；患者的SD范围分别为0.001 - 0.041 cm²/秒和0.001 - 0.011 cm²/秒）。两组均观察到随着吸入气体体积增加，平均ADC有轻微但显著的增加。
HP（3）氦气MRI的平均ADC和SD具有可重复性，并且在较高气体体积下能很好地区分健康对照者和肺气肿患者。该方法可靠，可能有助于深入了解肺气肿的病理生理学和病程。
