Oh Se-Hong, Lee Gawon, Lee Jongho
Department of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Republic of Korea.
Diagnostic Radiology, Diagnostics Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Hum Brain Mapp. 2025 Aug 15;46(12):e70307. doi: 10.1002/hbm.70307.
Measuring myelin concentration in the brain has important implications in basic science and clinical practice. In MRI, myelin water imaging (MWI) has been suggested as a surrogate biomarker that provides high sensitivity and specificity for myelin. However, multi-exponential fitting is ill-conditioned, and it is sensitive to noise and artifacts, particularly in vivo. To overcome the ill-conditioned fitting problem, the two-dimensional ViSTa myelin-weighted imaging technique was proposed, and it provides a substantially improved myelin-weighted image. However, it is based on a two-dimensional single-slice acquisition scheme, and it is a limitation. In this study, a whole brain-covered 3D ViSTa sequence, based on a 3D segmented echo planar imaging (EPI) sequence with a pair of slice selective inversion RF pulses, was proposed. To investigate the 3D ViSTa myelin weighted image, the distribution of myelin content in the white matter of the brain was measured using both conventional MWI and ViSTa MWI. The proposed 3D ViSTa method achieves a whole brain-covered (FOV = 240 × 240 × 128 mm) myelin water-weighted image in less than 8 min (1.5 × 1.5 × 4 mm) and does not require heavy post-processing. Pseudo-quantification (apparent MWF) can be provided by normalizing the ViSTa image with a PD-weighted image. The voxel-wise correlation between the conventional MWI and the 3D ViSTa yielded a mean correlation coefficient of 0.74 ± 0.03 (mean ± standard deviation of the five subjects), demonstrating a high spatial similarity in myelin-weighted contrast between the two maps. The proposed 3D ViSTa with pseudo-quantification may be useful in clinical applications when absolute quantification is not necessary.
测量大脑中的髓磷脂浓度在基础科学和临床实践中具有重要意义。在磁共振成像(MRI)中,髓磷脂水成像(MWI)已被提议作为一种替代生物标志物,它对髓磷脂具有高灵敏度和特异性。然而,多指数拟合是病态的,并且对噪声和伪影敏感,尤其是在体内。为了克服病态拟合问题,提出了二维ViSTa髓磷脂加权成像技术,它提供了显著改进的髓磷脂加权图像。然而,它基于二维单切片采集方案,这是一个局限性。在本研究中,提出了一种基于具有一对切片选择性反转射频脉冲的三维分段回波平面成像(EPI)序列的全脑覆盖三维ViSTa序列。为了研究三维ViSTa髓磷脂加权图像,使用传统MWI和ViSTa MWI测量了大脑白质中髓磷脂含量的分布。所提出的三维ViSTa方法在不到8分钟内(1.5×1.5×4毫米)获得全脑覆盖(视野 = 240×240×128毫米)髓磷脂水加权图像,并且不需要繁重的后处理。通过用质子密度加权图像对ViSTa图像进行归一化可以提供伪定量(表观MWF)。传统MWI与三维ViSTa之间的体素级相关性产生的平均相关系数为0.74±0.03(五名受试者的平均值±标准差),表明两张图之间在髓磷脂加权对比度方面具有高度的空间相似性。当不需要绝对定量时,所提出的具有伪定量的三维ViSTa在临床应用中可能有用。