Institute of Applied Physics, University of Tsukuba.
Magn Reson Med Sci. 2019 Jan 10;18(1):96-104. doi: 10.2463/mrms.tn.2018-0027. Epub 2018 May 24.
Magnetic resonance fingerprinting (MRF) is a promising framework that allows the quantification of multiple magnetic resonance parameters with a single scan. MRF using fast imaging with steady-state precession (MRF-FISP) has robustness to off-resonance artifacts and has many applications in inhomogeneous fields. However, the spoiler gradient used in MRF-FISP is sensitive to diffusion motion, and may lead to quantification errors when the spoiler moment increases. In this study, we examined the effect of the diffusion weighting in MRF-FISP caused by spoiler gradients. The T relaxation times were greatly underestimated when large spoiler moments were used. The T underestimation was prominent for tissues with large values of T and diffusion coefficients. The T bias was almost independent of the apparent diffusion coefficient (ADC) and T values when the ADC map was measured and incorporated into the matching process. These results reveal that the T underestimation resulted from the diffusion weighting caused by the spoiler gradients.
磁共振指纹成像（MRF）是一种很有前途的框架，可以在单次扫描中定量多个磁共振参数。使用稳态进动快速成像的 MRF（MRF-FISP）对离频伪影具有稳健性，并且在不均匀场中有许多应用。然而，MRF-FISP 中使用的扰断梯度对扩散运动很敏感，当扰断力矩增加时，可能会导致定量误差。在这项研究中，我们检查了扰断梯度在 MRF-FISP 中引起的扩散加权的影响。当使用大的扰断力矩时，T 弛豫时间会被大大低估。对于 T 值和扩散系数较大的组织，T 低估现象更为明显。当 ADC 图被测量并纳入匹配过程时，T 偏差几乎与表观扩散系数（ADC）和 T 值无关。这些结果表明，T 低估是由扰断梯度引起的扩散加权造成的。
