Svensson Jonas, Leander Peter, Maki Jeffrey H, Stahlberg Freddy, Olsson Lars E
Department of Radiation Physics, Malmö University Hospital, SE-205 02, Malmö, Sweden.
Magn Reson Imaging. 2002 Jan;20(1):49-57. doi: 10.1016/s0730-725x(02)00479-4.
In 3-D contrast-enhanced magnetic resonance (MR) angiography of the lower extremities the goal is most often to enhance arterial structures while keeping veins and surrounding tissue unenhanced. Imaging during steady-state concentration of a blood pool agent or during poor timing of an extra-cellular contrast medium may result in simultaneous venous enhancement, making interpretation of the angiogram difficult. The aim of this study was to develop a post-processing method to separate the arteries from the veins in standard contrast-enhanced MR angiograms. The method was based on the different accumulation of flow-induced phase in the arteries and veins of the lower extremities. The method was tested in both phantom experiments and volunteers undergoing 3-D contrast-enhanced MR angiography using both an extra-cellular contrast medium and a blood pool agent. In the phantom studies, opposite directional flow was successfully separated at mean flow velocities as low as 9 cm/s. In the volunteer studies, the larger veins were successfully extinguished while the larger arteries were left unaffected. In smaller vessels with low flow velocities the separation was less successful. This was most apparent in vessels not oriented superior-inferior. The method developed here is promising for separating arteries from veins in contrast-enhanced MR angiography although the results could be further improved by either a different pulse sequence design or combining this method with other segmentation methods.
在下肢三维对比增强磁共振（MR）血管造影中，目标通常是增强动脉结构，同时使静脉和周围组织不被增强。在血池造影剂稳态浓度期间成像或在细胞外造影剂注射时机不佳时成像，可能会导致静脉同时增强，从而使血管造影的解读变得困难。本研究的目的是开发一种后处理方法，以在标准对比增强MR血管造影中分离动脉和静脉。该方法基于下肢动脉和静脉中血流诱导相位的不同累积。该方法在模型实验和接受三维对比增强MR血管造影的志愿者中进行了测试，使用了细胞外造影剂和血池造影剂。在模型研究中，在平均流速低至9厘米/秒时成功分离了相反方向的血流。在志愿者研究中，较大的静脉被成功消除，而较大的动脉未受影响。在流速较低的较小血管中，分离不太成功。这在非上下方向走行的血管中最为明显。尽管通过不同的脉冲序列设计或将该方法与其他分割方法相结合可以进一步改善结果，但这里开发的方法在对比增强MR血管造影中分离动脉和静脉方面很有前景。
