Balleux-Buyens F, Jolivet O, Bittoun J, Herment A
Inserm, U678, Paris, F-75013, France. Faculté de Médecine Pitie-Salpêtrière, Université Pierre et Marie Curie, Paris, F-75013, France.
Phys Med Biol. 2006 Oct 7;51(19):4747-58. doi: 10.1088/0031-9155/51/19/002. Epub 2006 Sep 5.
Many methods have been proposed to extract pressure gradient maps from magnetic resonance (MR) images. They were based on the resolution of the haemodynamic model of Navier-Stokes and needed the flow acceleration to be known. Most used velocity data acquisition and computed acceleration from temporal and spatial derivatives of the velocity field. However, MR sequences have been developed in order to acquire the acceleration field directly. Here we compared direct MR measurements of acceleration field components with those calculated from MR velocity acquisitions. Two experimental phantoms were used to separately evaluate the inertial and convective components of the acceleration. Mathematical simulation of the convective phantom further explained the origin of the noise generated by the spatial and temporal derivatives of the velocity data, and the misregistration artefacts due to MR sequences. We found that direct measurement of the acceleration field generates less noise and fewer artefacts than calculation from velocity derivatives.
已经提出了许多从磁共振（MR）图像中提取压力梯度图的方法。这些方法基于纳维-斯托克斯血流动力学模型的分辨率，并且需要已知流动加速度。大多数方法使用速度数据采集，并根据速度场的时间和空间导数计算加速度。然而，已经开发出了直接获取加速度场的MR序列。在此，我们将加速度场分量的直接MR测量结果与从MR速度采集计算得到的结果进行了比较。使用了两个实验模型分别评估加速度的惯性分量和对流分量。对流模型的数学模拟进一步解释了速度数据的空间和时间导数产生噪声的原因，以及由于MR序列导致的配准伪影。我们发现，与从速度导数计算相比，加速度场的直接测量产生的噪声和伪影更少。
