IEEE J Biomed Health Inform. 2022 Sep;26(9):4508-4518. doi: 10.1109/JBHI.2022.3182969. Epub 2022 Sep 9.
Susceptibility tensor imaging (STI) is a promising tool for studying orientation-dependent tissue magnetic susceptibility and for mapping white matter fiber orientations complementary to diffusion tensor imaging (DTI). However, the limited head rotation range within modern head coils for data acquisition makes in vivo STI reconstruction ill-conditioned. Conventional STI reconstruction method is usually vulnerable to noise and requires sufficiently large head rotations to solve this ill-conditioned inverse problem. In this study, based on the recently proposed asymmetric STI (aSTI) model, a new method termed aSTI+ was proposed to improve in vivo STI reconstruction by enforcing isotropic susceptibility tensor inside cerebrospinal fluid (CSF) and applying morphology constraint in white matter. Experimental results showed superior performance of the proposed method with reduced noise, improved tissue contrast and better fiber orientation estimation over previous methods. Thus aSTI+ may promote in vivo human brain STI studies on white matter and myelin-related brain diseases.
磁化率张量成像（susceptibility tensor imaging，STI）是一种很有前途的工具，可用于研究与组织磁化率有关的各向异性，并绘制与弥散张量成像（diffusion tensor imaging，DTI）互补的白质纤维方向图。然而，现代头部线圈在采集数据时头部旋转范围有限，导致体内 STI 重建的条件不佳。传统的 STI 重建方法通常容易受到噪声的影响，并且需要足够大的头部旋转才能解决这个病态逆问题。在这项研究中，基于最近提出的不对称 STI（asymmetric STI，aSTI）模型，提出了一种新的方法，称为 aSTI+，通过在脑脊液（cerebrospinal fluid，CSF）内强制各向同性磁化率张量并在白质中应用形态学约束，来改善体内 STI 重建。实验结果表明，与先前的方法相比，该方法在减少噪声、提高组织对比度和更好地估计纤维方向方面具有更好的性能。因此，aSTI+可能会促进体内人脑 STI 对白质和与髓鞘相关的脑部疾病的研究。
