Herment A, Mousseaux E, De Cesare A, Jolivet O, Dumée P, Todd-Pokropek A, Bittoun J
INSERM U 494, CHU Pitié, 75013 Paris, France.
J Magn Reson Imaging. 1999 Nov;10(5):851-60. doi: 10.1002/(sici)1522-2586(199911)10:5<851::aid-jmri34>3.0.co;2-i.
A technique dedicated to spatial regularization of magnetic resonance (MR) velocity data has been implemented to improve flow image quality. It is assumed that neighboring flow-velocity pixels are partially correlated, although large-velocity discontinuities remain possible. Increasing MR signal magnitude due to the in-flow effect also is used to enhance further reliability of the estimated velocity. By using an eight-step Fourier-encoding approach, 162 "reference" velocity images acquired in the ascending aorta from six healthy volunteers were compared with "raw" and "regularized" images that were computed from only two gradient steps. The mean square error decreased from 0.12 m(2) x s(-2) to 0.06 m(2) x s(-2) (P < 10-9) for velocity pixel values and from 1929 ml(2) x s(-2) to 1336 ml(2) x s(-2) (P < 0.01) for instantaneous flow rates. The regularization of two-step data sets provides the same velocity image quality as that found after using three-step data sets without regularization. The method can be applied to phase-velocity data sets of any MR technique to reduce velocity noise. J. Magn. Reson. Imaging 1999;10:851-860.
一种专门用于磁共振（MR）速度数据空间正则化的技术已被实现，以提高血流图像质量。假定相邻的血流速度像素存在部分相关性，尽管大的速度不连续性仍然可能存在。流入效应导致的磁共振信号强度增加也被用于进一步提高估计速度的可靠性。通过使用八步傅里叶编码方法，将从六名健康志愿者升主动脉获取的162幅“参考”速度图像与仅从两个梯度步计算得到的“原始”和“正则化”图像进行比较。对于速度像素值，均方误差从0.12 m²×s⁻²降至0.06 m²×s⁻²（P < 10⁻⁹）；对于瞬时流速，均方误差从1929 ml²×s⁻²降至1336 ml²×s⁻²（P < 0.01）。两步数据集的正则化提供了与未正则化的三步数据集相同的速度图像质量。该方法可应用于任何磁共振技术的相速度数据集，以降低速度噪声。《磁共振成像杂志》1999年；10:851 - 860。
