Henk Christine B, Grampp Stephan, Koller Jeanette, Schoder Maria, Frank Herbert, Klaar Ursula, Gomischek Gregor, Mostbeck Gerhard H
Department of Radiology, University of Vienna, Ludwig Boltzmann Institute for Radiological Tumor Diagnosis; Währingergürtel 18-20, 1090 Vienna, Austria.
Eur Radiol. 2002 Jun;12(6):1523-31. doi: 10.1007/s00330-001-1176-2. Epub 2001 Nov 14.
The aim of this study was to evaluate a velocity-encoded cine-MR (VEC-MR) sequence in measuring flow velocities up to two times the velocity encoding value (VENC) in a flow phantom and to validate the method for assessing poststenotic jet velocities in postoperative patients after aortic coarctation. In vitro, a flow phantom was used (0.5T; TR/TE: 51/8 ms, flip angle=30 degrees, FOV=280 mm, 128x256 matrix VENC 40 or 80 cm/s). On binary images, maximum flow velocities (V(max)) were calculated with a region of interest (ROI, 8 pixels). With aliasing, V(max) was calculated by VENC+(V(aliasing)). In vivo, 16 postoperative patients after aortic coarctation underwent double-oblique VEC-MR imaging through the aortic arch (ECG triggering, 16 phases/RR, TR=600-800 ms, flow-encoding cranio-caudal, VENC=2 m/s). Peak systolic velocities were measured and transthoracic Doppler echocardiography (TTDE) was performed. In vitro, there were excellent correlations for MR velocity measurements with and without aliasing ( r=0.99) and for true and MR-derived flow velocities ( r=0.99). In vivo, there was good correlation between VEC-MR and TTDE-assessed V(max) values in the aorta at the former coarctation site ( r=0.90, n=16). Aliasing occurred in 13 patients. VEC-MR is a useful modality for assessing jet velocities in the follow-up of patients after aortic coarctation. Despite of aliasing, accurate velocity measurements up to two times VENC are possible using binary images.
本研究的目的是评估速度编码电影磁共振（VEC-MR）序列在血流模型中测量高达两倍速度编码值（VENC）的流速的能力，并验证该方法在评估主动脉缩窄术后患者的狭窄后射流速度方面的有效性。在体外，使用了一个血流模型（0.5T；TR/TE：51/8 ms，翻转角 = 30度，视野 = 280 mm，128x256矩阵，VENC 40或80 cm/s）。在二值图像上，使用感兴趣区域（ROI，8像素）计算最大流速（V(max)）。存在混叠时，V(max)通过VENC+(V(混叠))计算。在体内，16例主动脉缩窄术后患者通过主动脉弓进行双斜VEC-MR成像（心电图触发，16个时相/RR，TR = 600 - 800 ms，头足向血流编码，VENC = 2 m/s）。测量收缩期峰值流速并进行经胸多普勒超声心动图（TTDE）检查。在体外，有无混叠情况下的磁共振速度测量之间以及真实流速与磁共振衍生流速之间均存在极好的相关性（r = 0.99）。在体内，VEC-MR与TTDE评估的原缩窄部位主动脉V(max)值之间存在良好的相关性（r = 0.90，n = 16）。13例患者出现混叠。VEC-MR是评估主动脉缩窄术后患者随访中射流速度的一种有用方法。尽管存在混叠，但使用二值图像仍可准确测量高达两倍VENC的流速。
