Lin W, Haacke E M, Smith A S
Department of Radiology, University Hospitals of Cleveland, OH 44106.
J Magn Reson Imaging. 1991 May-Jun;1(3):327-36. doi: 10.1002/jmri.1880010311.
Factors affecting blood vessel lumen definition for two-dimensional and three-dimensional inflow magnetic resonance (MR) imaging methods are considered. Vessel definition is affected (a) by the amount of dephasing of the blood in the vessels, both for uncompensated and velocity-compensated gradients; (b) by the image reconstruction technique (normal Fourier reconstruction when asymmetric echoes are collected or a maximum-intensity projection technique in post-processing); (c) by loss of signal due to T2* dephasing; (d) by misregistration; (e) by vessel wall motion; and (f) by partial-volume effects. The first two factors were found to dominate for resolution on the order of 1 mm3. To overcome these dephasing problems, the authors developed asymmetric echo, velocity-compensated sequences with TEs as short as 4.8 msec. The data were then reconstructed with an iterative partial Fourier algorithm, enabling improved lumen definition to be obtained in phantoms and in vivo.
研究了影响二维和三维流入磁共振（MR）成像方法中血管腔定义的因素。血管定义受以下因素影响：（a）血管内血液的去相位量，包括未补偿梯度和速度补偿梯度的情况；（b）图像重建技术（收集不对称回波时的常规傅里叶重建或后处理中的最大强度投影技术）；（c）由于T2*去相位导致的信号损失；（d）配准错误；（e）血管壁运动；以及（f）部分容积效应。发现前两个因素在约1立方毫米的分辨率下起主导作用。为克服这些去相位问题，作者开发了回波不对称、速度补偿且回波时间短至4.8毫秒的序列。然后用迭代部分傅里叶算法重建数据，从而在体模和体内均能获得改善的管腔定义。
