Division of Medical and Biological Informatics, German Cancer Research Center, Heidelberg, Germany.
Neuroimage. 2010 May 15;51(1):242-51. doi: 10.1016/j.neuroimage.2010.02.007. Epub 2010 Feb 10.
The quantification of fiber integrity is central to the clinical application of diffusion imaging. Compared to diffusion tensor imaging (DTI), Q-ball imaging (QBI) allows for the depiction of multiple fiber directions within a voxel. However, this advantage has not yet been shown to translate directly to superior quantification of fiber integrity. Furthermore, recent developments in QBI reconstruction with solid angle consideration have led to sharper and intrinsically normalized orientation distribution functions. The implications of this technique on quantification are also unknown. To investigate this, the generalized fractional anisotropy (GFA) from the original and the more recent QBI reconstruction scheme and the DTI derived fractional anisotropy (FA) were evaluated comparatively using Monte Carlo simulations and real MRI measurements of crossing fiber phantoms. Contrast-to-noise ratio, accuracy, independence of the acquisition setup and the relation of single fiber anisotropies to measured anisotropy in crossings were assessed. In homogeneous single-fiber regions at b-values around 1000 s/mm2, the FA performed best. While the original QBI reconstruction does not show a clear advantage even at higher b-values and in crossing regions, the new reconstruction scheme yields superior properties and is recommended for quantification at higher b-values and especially in regions of heterogeneous fiber configuration.
纤维完整性的量化是扩散成像临床应用的核心。与扩散张量成像（DTI）相比，Q 球成像（QBI）允许在体素内描绘多个纤维方向。然而，这一优势尚未被证明能够直接转化为纤维完整性的优越量化。此外，最近在考虑立体角的 QBI 重建方面的发展导致了更清晰和内在归一化的方向分布函数。该技术对量化的影响也尚不清楚。为了研究这一点，使用蒙特卡罗模拟和交叉纤维幻像的真实 MRI 测量，对原始和最近的 QBI 重建方案的广义各向异性分数（GFA）以及 DTI 导出的各向异性分数（FA）进行了比较评估。评估了对比噪声比、准确性、采集设置的独立性以及单纤维各向异性与交叉处测量各向异性的关系。在 b 值约为 1000 s/mm2 的同质单纤维区域，FA 的表现最佳。虽然原始的 QBI 重建即使在更高的 b 值和交叉区域也没有明显的优势，但新的重建方案具有更好的性能，建议在更高的 b 值下进行量化，特别是在纤维结构不均匀的区域。
