Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, Royal Oak, MI, USA.
Ultrasound Obstet Gynecol. 2009 Dec;34(6):673-7. doi: 10.1002/uog.7446.
The main goal was to develop a reproducible method for estimating the diffusion of water in human fetal lung tissue using diffusion-weighted imaging (DWI). A secondary objective was to determine the relationship of the apparent diffusion coefficients (ADCs) in the fetal lung to menstrual age and total lung volume.
Normal pregnant volunteers were scanned on a 1.5-Tesla (T) magnetic resonance imaging (MRI) system. The MRI system was equipped with 40-mT/m gradients (slew rate 200 T/m/s, rise time 0.2 ms). A six-channel body array coil was used for signal reception. Single-shot DWI utilized TE/TR 125/3400 ms, slice thickness 4 mm, field of view 280 mm x 280 mm, interslice gap 0.8 mm and a matrix of 128 x 128. The voxel size was 2.5 mm x 2.5 mm x 4.0 mm. Two b-values (0 and 1000) were chosen along three orthogonal directions. ADC maps were created using assigned b-values. Simple linear regression was performed with Pearson correlation coefficient. Interexaminer and intraexaminer bias, and 95% limits of agreement (LOA) were determined using Bland-Altman plots.
Forty-seven scans were performed at a mean +/- SD of 29.2 +/- 4.5 weeks. The median coefficient of variation for ADC was 5.6% (interquartile range, 4.0-8.1%). No differences in ADC values were found between right and left lungs. Normally distributed ADC measurements were not significantly correlated with either total lung volume (r(2) = 0.0001, P = 0.94) or menstrual age (r(2) = 0.003, P = 0.70). The mean ADC value was 1.75 (95% CI, 1.63-1.86). Mean +/- SD intraexaminer bias was -0.15 +/- 2.3 (95% LOA, -4.7 to + 4.4) and interexaminer bias was 2.2 +/- 3.5 (95% LOA, -4.7 to + 9.1).
Our findings suggest that ADC measurements of the fetal lung are reproducible between blinded examiners and are independent of menstrual age, as well as lung volume.
本研究旨在利用扩散加权成像（DWI）开发一种可重现的方法来评估人胎儿肺组织中水分子的扩散。次要目标是确定胎儿肺组织的表观扩散系数（ADC）与月经龄和总肺容量的关系。
正常妊娠志愿者在 1.5T 磁共振成像（MRI）系统上进行扫描。MRI 系统配备了 40mT/m 的梯度（上升时间 200T/m/s，上升时间 0.2ms）。使用六通道体线圈接收信号。单次激发 DWI 采用 TE/TR 125/3400ms、层厚 4mm、视野 280mm×280mm、层间间隙 0.8mm 和矩阵 128×128。体素大小为 2.5mm×2.5mm×4.0mm。在三个正交方向上选择两个 b 值（0 和 1000）。使用指定的 b 值创建 ADC 图。使用 Pearson 相关系数进行简单线性回归。采用 Bland-Altman 图确定观察者内和观察者间的偏差以及 95%的一致性区间（LOA）。
在平均 29.2±4.5 周的时间内进行了 47 次扫描。ADC 的中位变异系数为 5.6%（四分位间距，4.0-8.1%）。左右肺之间的 ADC 值无差异。ADC 测量值呈正态分布，与总肺容量（r²=0.0001，P=0.94）或月经龄（r²=0.003，P=0.70）均无显著相关性。平均 ADC 值为 1.75（95%CI，1.63-1.86）。观察者内平均偏差为-0.15±2.3（95%LOA，-4.7 至+4.4），观察者间偏差为 2.2±3.5（95%LOA，-4.7 至+9.1）。
我们的研究结果表明，胎儿肺 ADC 值在盲法观察者之间具有可重复性，并且与月经龄以及肺容量无关。
