Department of Radiology, University of California, San Diego, La Jolla, CA, USA.
Department of Radiology, University of California, San Diego, La Jolla, CA, USA; Shu Chien-Gene Lay Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
Neuroimage. 2024 Aug 1;296:120666. doi: 10.1016/j.neuroimage.2024.120666. Epub 2024 Jun 1.
Direct imaging of semi-solid lipids, such as myelin, is of great interest as a noninvasive biomarker of neurodegenerative diseases. Yet, the short T 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 DO exchange and freeze-drying for complete water removal. Sufficiently high MR signals were detected with the 3D UTE sequence, which showed an ultrashort T* of ∼77-271 µs and a short T 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.
直接对类脂半固体（如髓磷脂）成像，作为神经退行性疾病的一种非侵入性生物标志物具有重要意义。然而，类脂半固体质子的短 T2 弛豫时间阻碍了通过传统磁共振成像（MRI）脉冲序列进行直接检测。在这项研究中，我们研究了三维超短回波时间（3D UTE）序列是否可以直接采集膜脂的信号。从市售血液中收集红细胞（RBC）的膜脂作为髓磷脂类脂双层的一般模型，并进行 DO 交换和冷冻干燥以完全去除水分。3D UTE 序列检测到了足够高的 MR 信号，对于类脂半固体 RBC 膜，其 T*为约 77-271µs，T1 为约 189ms。这些测量结果可以为基于 UTE 的直接在体成像膜脂的序列设计提供指导。
