Abstract：
Direct imaging of semi-solid lipids, such as myelin, is of great interest as a noninvasive biomarker of neurodegenerative diseases. Yet, the short T2 relaxation times of semi-solid lipid protons hamper direct detection through conventional magnetic resonance imaging (MRI) pulse sequences. In this study, we examined whether a three-dimensional ultrashort echo time (3D UTE) sequence can directly acquire signals from membrane lipids. Membrane lipids from red blood cells (RBC) were collected from commercially available blood as a general model of the myelin lipid bilayer and subjected to D2O exchange and freeze-drying for complete water removal. Sufficiently high MR signals were detected with the 3D UTE sequence, which showed an ultrashort T2* of ∼77-271 µs and a short T1 of ∼189 ms for semi-solid RBC membrane lipids. These measurements can guide designing UTE-based sequences for direct in vivo imaging of membrane lipids.
摘要：
半固体脂质的直接成像，如髓磷脂，作为神经退行性疾病的非侵入性生物标志物非常感兴趣。然而，半固体脂质质子的短T2弛豫时间阻碍了通过常规磁共振成像（MRI）脉冲序列的直接检测。在这项研究中,我们检查了三维超短回波时间（3DUTE）序列是否可以直接从膜脂质获取信号。从市售血液中收集来自红细胞（RBC）的膜脂质作为髓磷脂脂质双层的一般模型，并进行D2O交换和冷冻干燥以完全去除水。使用3DUTE序列检测到足够高的MR信号，这表明半固体红细胞膜脂质的超短T2*为77-271µs，短T1为189ms。这些测量可以指导基于UTE的序列的设计，用于膜脂质的直接体内成像。
