Masaryk T J, Ross J S, Modic M T, Lenz G W, Haacke E M
Department of Radiology, University Hospitals of Cleveland, Case Western Reserve University, OH 44106.
Radiology. 1988 Feb;166(2):461-6. doi: 10.1148/radiology.166.2.3336721.
To devise and implement an in-plane magnetic resonance angiography examination of the carotid bifurcation capable of producing high-resolution images, the authors examined 19 normal carotid arteries and 14 patients with angiographically documented disease with two flow-correction techniques: a three-gradient, velocity-refocused technique with spin-echo (SE) and gradient-echo sequences, and a four-gradient velocity- and acceleration-corrected SE technique. With use of three equal gradients in the read direction, velocity-related phase changes were minimized by placing the dephasing gradient after the 180 degree pulse and near the read gradient. Acceleration effects were minimized through the use of short echo times and cardiac gating. Both velocity- and acceleration-produced phase changes were corrected with the four-gradient scheme but at the expense of some limitations in spatial resolution. Both techniques consistently produced satisfactory images of the carotid bifurcation in healthy individuals. However, the results indicate that the present gradient-phase modulation techniques have several drawbacks, including susceptibility to patient motion, overlapping with the jugular vein, and inability to image carotid stenosis accurately due to turbulence.
为了设计并实施一项能够产生高分辨率图像的颈动脉分叉平面磁共振血管造影检查，作者使用两种血流校正技术对19条正常颈动脉和14例血管造影证实患有疾病的患者进行了检查：一种是采用自旋回波（SE）和梯度回波序列的三梯度、速度重聚焦技术，另一种是四梯度速度和加速度校正的SE技术。在读取方向上使用三个相等的梯度，通过将去相位梯度置于180度脉冲之后并靠近读取梯度，使与速度相关的相位变化最小化。通过使用短回波时间和心脏门控，将加速度效应最小化。速度和加速度产生的相位变化都用四梯度方案进行了校正，但代价是空间分辨率存在一些限制。两种技术在健康个体中均能持续产生令人满意的颈动脉分叉图像。然而，结果表明，目前的梯度相位调制技术存在几个缺点，包括易受患者运动影响、与颈静脉重叠以及由于湍流而无法准确成像颈动脉狭窄。
