NOISE-REDUCTION IN 3-DIMENSIONAL PHASE-CONTRAST MR VELOCITY-MEASUREMENTS
NOISE-REDUCTION IN 3-DIMENSIONAL PHASE-CONTRAST MR VELOCITY-MEASUREMENTS
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DOI：
10.1002/jmri.1880030407
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发表时间：
1993-07-01
期刊：
影响因子：
--
通讯作者：
PELC, NJ
中科院分区：
文献类型：
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作者：
SONG, SM;NAPEL, S;PELC, NJ
作者开发了一种方法，利用血液不可压缩的特性来降低三维（3D）相对比磁共振（MR）速度测量中的噪声，因此描述其流动的速度场必须是无发散的。通过希尔伯特空间中的投影运算结合无散度条件。将三维相衬磁共振成像得到的速度场投影到无散度的速度场空间。由于投影运算消除了非发散性的噪声成分，因此实现了噪声的降低。信噪比（S/N）增益约为15%-25%。这种降噪的直接效果体现在高质量的相衬磁共振血管成像中。另外，信噪比增益可以换取成像时间的减少和/或空间分辨率的提高。
The authors have developed a method to reduce noise in three-dimensional (3D) phase-contrast magnetic resonance (MR) velocity measurements by exploiting the property that blood is incompressible and, therefore, the velocity field describing its flow must be divergence-free. The divergence-free condition is incorporated by a projection operation in Hilbert space. The velocity field obtained with 3D phase-contrast MR imaging is projected onto the space of divergence-free velocity fields. The reduction of noise is achieved because the projection operation eliminates the noise component that is not divergence-free. Signal-to-noise ratio (S/N) gains on the order of 15%-25% were observed. The immediate effect of this noise reduction manifests itself in higher-quality phase-contrast MR angiograms. Alternatively, the S/N gain can be traded for a reduction in imaging time and/or improved spatial resolution.