Galjee M A, van Rossum A C, Doesburg T, van Eenige M J, Visser C A
Department of Cardiology, Free University Hospital Amsterdam, The Netherlands.
Circulation. 1996 Feb 15;93(4):660-6. doi: 10.1161/01.cir.93.4.660.
Previous studies have demonstrated the high sensitivity and moderate specificity of standard magnetic resonance (MR) spin-echo (SE) and gradient-echo (GE) techniques in predicting the patency of coronary artery bypass grafts. These techniques, however, do not provide quantitative information. Therefore, the objectives of this study were first to investigate whether MR cine GE images, performed in addition to standard SE images, have additional value for the assessment of graft patency and second to assess the graft function by measuring the flow pattern and flow rate with MR phase velocity imaging.
Forty-seven patients with previous histories of coronary artery bypass grafting underwent angiography and MR SE and cine GE phase velocity imaging. SE and GE images were evaluated by three independent observers blinded to the angiographic results. The spatial mean velocity and volume flow were measured and repeated for each image at consecutive 50-millisecond intervals throughout the cardiac cycle. The 47 patients had 98 proximal aortotomies, of which 60 were single and 38 sequential grafts. Seventy-three grafts were patent; 25 were occluded. Eighty-four grafts (86%) were eligible for comparison of the results of SE and GE images. Assessment of patency was inconclusive on SE images in 7 grafts (5 occluded by angiography) and on GE images in 7 grafts (2 occluded). A comparison of the results of contrast angiography and SE and GE MR imaging techniques showed that both techniques had a high sensitivity (both 98%) and somewhat lower specificity (85% and 88%, respectively) for graft patency. Combined analysis of the SE and GE images did not improve the accuracy. The strength of the interobserver agreement on GE images was good (kappa = 0.66), whereas on SE images the agreement was moderate (kappa = 0.51). Adequate MR phase velocity profiles were obtained in 62 (85%) of the 73 angiographically patent grafts. Graft flow was characterized by a balanced biphasic forward flow pattern. The volume flow of sequential grafts to 3 regions (136 +/- 106 mL/min) was significantly higher than in single grafts (63 +/- 41 mL/min, P < .01).
Considering the good interobserver agreement and the 85% success rate of quantitative flow measurements, cine GE phase velocity mapping is a promising clinical tool in the noninvasive assessment of graft patency and function.
先前的研究已证明标准磁共振（MR）自旋回波（SE）和梯度回波（GE）技术在预测冠状动脉搭桥移植血管通畅性方面具有高敏感性和中等特异性。然而，这些技术无法提供定量信息。因此，本研究的目的首先是调查除标准SE图像外进行的MR电影GE图像对于评估移植血管通畅性是否具有额外价值，其次是通过MR相速度成像测量血流模式和流速来评估移植血管功能。
47例有冠状动脉搭桥移植病史的患者接受了血管造影以及MR SE和电影GE相速度成像检查。由三位对血管造影结果不知情的独立观察者对SE和GE图像进行评估。在整个心动周期中，以连续50毫秒的间隔对每个图像测量并重复测量空间平均速度和容积流量。47例患者有98处近端主动脉吻合口，其中60处为单支移植血管，38处为序贯移植血管。73支移植血管通畅；25支闭塞。84支移植血管（86%）符合SE和GE图像结果比较的条件。7支移植血管（血管造影显示5支闭塞）的SE图像和7支移植血管（2支闭塞）的GE图像对通畅性的评估不明确。对比血管造影与SE和GE MR成像技术的结果显示，两种技术对移植血管通畅性均具有高敏感性（均为98%）和略低的特异性（分别为85%和88%）。SE和GE图像的联合分析并未提高准确性。观察者间对GE图像的一致性强度良好（kappa = 0.66），而对SE图像的一致性为中等（kappa = 0.51）。在73支血管造影显示通畅的移植血管中，62支（85%）获得了足够的MR相速度剖面图。移植血管血流的特征为平衡的双相正向血流模式。向3个区域的序贯移植血管的容积流量（136±106 mL/分钟）显著高于单支移植血管（63±41 mL/分钟，P <.01）。
考虑到观察者间良好的一致性以及定量血流测量85%的成功率，电影GE相速度成像在无创评估移植血管通畅性和功能方面是一种有前景的临床工具。
