Jansson Tomas, Hernandez-Andrade Edgar, Lingman Göran, Marsál Karel
Department of Electrical Measurements, Lund University, Lund, Sweden.
Ultrasound Med Biol. 2003 Nov;29(11):1551-9. doi: 10.1016/s0301-5629(03)01050-0.
Perfusion estimation of the fetal lung is an important predictor of its maturity and function after birth. Ultrasound (US) power Doppler has previously been used to assess the perfusion of the fetal lung, based on the mean pixel intensity (MPI) over a region-of-interest (ROI). The drawback is that the MPI is not only dependent on the amount of flowing blood, but also depth, gain and attenuation in overlying tissue layers. In this study, power Doppler images have been analysed according to a previously published method that attempts to compensate for such unwanted variations, resulting in a measure termed fractional moving blood volume (FMBV). A total of 29 singleton pregnancies with normally grown fetuses were evaluated after 35 weeks of gestation. For reliable interpatient comparisons, we found it always necessary to use a well-defined section of the fetal lung. Therefore, all scans were performed in a transverse plane of the fetal thorax with a four-chamber view of the heart, through the intercostal space. ROIs in 12 left and 17 right fetal lungs were defined (the fetal lung closest to the transducer was always examined). No differences in estimated FMBV or MPI were found between left and right lungs. Similarly, there was no significant difference between images acquired during systole and diastole. FMBV is compensated for depth and, also, for other sources of power variation, as reflected in the coefficient of variation: 0.14 for FMBV and 0.24 for MPI. A scan on a test phantom reveals that the power in dB is linearly related to velocity over a limited range, suggesting that FMBV might be useful for discriminating between normal and decreased fetal lung perfusion.
胎儿肺灌注评估是其出生后成熟度和功能的重要预测指标。超声功率多普勒此前已被用于评估胎儿肺灌注，其依据是感兴趣区域（ROI）上的平均像素强度（MPI）。缺点是MPI不仅取决于流动血液的量，还取决于上覆组织层的深度、增益和衰减。在本研究中，根据先前发表的一种方法对功率多普勒图像进行了分析，该方法试图补偿此类不必要的变化，从而得出一种称为分数移动血容量（FMBV）的测量值。共有29例单胎妊娠且胎儿生长正常的孕妇在妊娠35周后接受了评估。为了进行可靠的患者间比较，我们发现始终有必要使用胎儿肺的一个明确界定的区域。因此，所有扫描均在胎儿胸部的横断面上进行，心脏呈四腔心视图，穿过肋间间隙。在12个左肺和17个右肺中定义了ROI（总是检查最靠近换能器的胎儿肺）。左右肺之间在估计的FMBV或MPI方面未发现差异。同样，在收缩期和舒张期采集的图像之间也没有显著差异。FMBV补偿了深度以及功率变化的其他来源，如变异系数所示：FMBV为0.14，MPI为0.24。对测试体模的扫描显示，在有限范围内，以分贝为单位的功率与速度呈线性相关，这表明FMBV可能有助于区分正常和减少的胎儿肺灌注。
