Department of Pathophysiology, Second Faculty of Medicine, Charles University, Praha 5, Czech Republic.
Physiol Res. 2023 Dec 29;72(S5):S573-S585. doi: 10.33549/physiolres.935250.
Magnetic Resonance Imaging (MRI) has revolutionized our ability to non-invasively study the brain's structural and functional properties. However, detecting myelin, a crucial component of white matter, remains challenging due to its indirect visibility on conventional MRI scans. Myelin plays a vital role in neural signal transmission and is associated with various neurological conditions. Understanding myelin distribution and content is crucial for insights into brain development, aging, and neurological disorders. Although specialized MRI sequences can estimate myelin content, these are time-consuming. Also, many patients sent to specialized neurological centers have an MRI of the brain already scanned. In this study, we focused on techniques utilizing standard MRI T1-weighted (T1w) and T2 weighted (T2w) sequences commonly used in brain imaging protocols. We evaluated the applicability of the T1w/T2w ratio in assessing myelin content by comparing it to quantitative T1 mapping (qT1). Our study included 1 healthy adult control and 7 neurologic patients (comprising both pediatric and adult populations) with epilepsy originating from focal epileptogenic lesions visible on MRI structural scans. Following image acquisition on a 3T Siemens Vida scanner, datasets were co registered, and segmented into anatomical regions using the Fastsurfer toolbox, and T1w/T2w ratio maps were calculated in Matlab software. We further assessed interhemispheric differences in volumes of individual structures, their signal intensity, and the correlation of the T1w/T2w ratio to qT1. Our data demonstrate that in situations where a dedicated myelin-sensing sequence such as qT1 is not available, the T1w/T2w ratio provides significantly better information than T1w alone. By providing indirect information about myelin content, this technique offers a valuable tool for understanding the neurobiology of myelin-related conditions using basic brain scans.
磁共振成像(MRI)极大地提高了我们非侵入性地研究大脑结构和功能特性的能力。然而,由于常规 MRI 扫描中髓鞘的间接可见性,检测髓鞘仍然具有挑战性。髓鞘在神经信号传递中起着至关重要的作用,与各种神经状况有关。了解髓鞘的分布和含量对于深入了解大脑发育、衰老和神经紊乱至关重要。虽然专门的 MRI 序列可以估计髓鞘含量,但这些序列耗时较长。此外,许多送往专门神经科中心的患者已经进行过脑部 MRI 扫描。在这项研究中,我们专注于利用标准 MRI T1 加权(T1w)和 T2 加权(T2w)序列的技术,这些序列通常用于脑成像方案。我们通过将 T1w/T2w 比值与定量 T1 映射(qT1)进行比较,评估了 T1w/T2w 比值在评估髓鞘含量方面的适用性。我们的研究包括 1 名健康成年人对照和 7 名患有癫痫的神经科患者(包括儿科和成人患者),他们的癫痫起源于 MRI 结构扫描可见的局灶性致痫性病变。在 3T 西门子 Vida 扫描仪上获取图像后,使用 Fastsurfer 工具箱对数据集进行配准和分割为解剖区域,并在 Matlab 软件中计算 T1w/T2w 比值图。我们进一步评估了个体结构的半球间体积差异、它们的信号强度以及 T1w/T2w 比值与 qT1 的相关性。我们的数据表明,在没有专门的髓鞘敏感序列(如 qT1)的情况下,T1w/T2w 比值比单独使用 T1w 提供了更好的信息。通过提供有关髓鞘含量的间接信息,该技术为使用基本的脑部扫描来理解与髓鞘相关的条件的神经生物学提供了一个有价值的工具。
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