Bhat Aarti Hejmadi, Corbett Virginia N, Liu Ruolan, Carpenter Nathan D, Liu Nick W, Wu Anna M, Hopkins Graham D, Li Xiaokui, Sahn David J
Oregon Health and Science University, Portland 97239-3098, USA.
J Ultrasound Med. 2004 Sep;23(9):1151-9. doi: 10.7863/jum.2004.23.9.1151.
This study was designed to validate a slow-sweep real-time 4-dimensional (4D) spatiotemporal image correlation method for producing quantitatively accurate dynamic fetal heart images using an in vitro pulsatile balloon model and apparatus.
To model fetal heart chambers, asymmetric double-walled finger stalls (tips of surgical latex gloves) were used and attached to a laboratory-designed circuit that allowed calibrated changes in the inner balloon volume as well as an intermediate gel mass interposed between the 2 layers. The water-submerged model was attached to a small-volume pulsatile pump to produce phasic changes in volume within the inner balloon at a fixed rate. A sonography system with 4D spatiotemporal image correlation (STIC) capabilities was used for 3-dimensional (3D) and 4D data acquisition. Volume data were analyzed by customized radial summation techniques with 4D data analysis software and compared with known volumes and masses.
Fifty-six individual volumes ranging from 2.5 to 10 mL were analyzed. Volume and mass measurements with 4D STIC were highly correlated (R2 > 0.90). The mean percentage error was better (<6%) for volumes exceeding 4 mL and was as low as 0.3% for 6-mL estimations. Measurements in the diastolic phase were the most accurate, followed by mass estimations equivalent to chamber walls. There was a wider range of percentage error in the lowest volumes tested (2.5 mL), which might have arisen from difficulties in spatial resolution or distortions from within the model apparatus itself. Resolution limitations of 4D technology in combination with extremely small volume targets may explain higher error rates at these small volumes.
Four-dimensional STIC is an acceptably accurate method for volume and mass estimations in the ranges comparable with mid- and late-gestation fetal hearts. It is particularly accurate for diastolic estimations, for chamber wall mass measurements, and at volumes of greater than 2.5 mL. This study validates use of 4D STIC technology to overcome the limitations of nongated 3D technology for phasic and quantitative assessments in fetal echocardiography.
本研究旨在使用体外搏动气球模型和装置验证一种慢扫实时四维（4D）时空图像相关方法，以生成定量准确的动态胎儿心脏图像。
为模拟胎儿心脏腔室，使用不对称双壁指套（手术乳胶手套指尖）并连接到实验室设计的电路，该电路允许对内部气球体积进行校准变化，以及在两层之间插入中间凝胶块。将水浸模型连接到小体积搏动泵，以固定速率在内部气球内产生体积的相位变化。使用具有4D时空图像相关（STIC）功能的超声检查系统进行三维（3D）和4D数据采集。通过定制的径向求和技术和4D数据分析软件对体积数据进行分析，并与已知体积和质量进行比较。
分析了56个个体体积，范围从2.5到10 mL。4D STIC的体积和质量测量高度相关（R2>0.90）。对于超过4 mL的体积，平均百分比误差更好（<6%），对于6 mL估计低至0.3%。舒张期测量最准确，其次是相当于室壁的质量估计。在测试的最小体积（2.5 mL）中，百分比误差范围更广，这可能是由于空间分辨率困难或模型装置本身内部的失真所致。4D技术的分辨率限制与极小体积目标相结合，可能解释了这些小体积下较高的误差率。
四维STIC是一种在与妊娠中期和晚期胎儿心脏相当的范围内进行体积和质量估计的可接受的准确方法。对于舒张期估计、室壁质量测量以及大于2.5 mL的体积，它特别准确。本研究验证了使用4D STIC技术克服非门控3D技术在胎儿超声心动图中进行相位和定量评估的局限性。
