The MRI Institute for Biomedical Research, Detroit, Michigan, USA.
Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.
J Magn Reson Imaging. 2018 Mar;47(3):621-633. doi: 10.1002/jmri.25809. Epub 2017 Jul 21.
To demonstrate the potential of imaging cerebral arteries and veins with ferumoxytol using susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM).
The relationships between ferumoxytol concentration and the apparent susceptibility at 1.5T, 3T, and 7T were determined using phantom data; the ability of visualizing subvoxel vessels was evaluated using simulations; and the feasibility of using ferumoxytol to enhance the visibility of small vessels was confirmed in three healthy volunteers at 7T(with doses 1 mg/kg to 4 mg/kg). The visualization of the lenticulostriate arteries and the medullary veins was assessed by two raters and the contrast-to-noise ratios (CNRs) of these vessels were measured.
The relationship between ferumoxytol concentration and susceptibility was linear with a slope 13.3 ± 0.2 ppm·mg ·mL at 7T. Simulations showed that SWI data with an increased dose of ferumoxytol, higher echo time (TE), and higher imaging resolution improved the detection of smaller vessels. With 4 mg/kg ferumoxytol, voxel aspect ratio = 1:8, TE = 10 ms, the diameter of the smallest detectable artery was approximately 50μm. The rating score for arteries was improved from 1.5 ± 0.5 (precontrast) to 3.0 ± 0.0 (post-4 mg/kg) in the in vivo data and the apparent susceptibilities of the arteries (0.65 ± 0.02 ppm at 4 mg/kg) agreed well with the expected susceptibility (0.71 ± 0.05 ppm).
The CNR for cerebral vessels with ferumoxytol can be enhanced using SWI, and the apparent susceptibilities of the arteries can be reliably quantified using QSM. This approach improves the imaging of the entire vascular system outside the capillaries and may be valuable for a variety of neurodegenerative diseases which involve the microvasculature.
1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:621-633.
利用磁敏感加权成像（SWI）和定量磁敏感图（QSM）显示用氧化铁进行脑动脉和静脉成像的潜力。
使用体模数据确定 1.5T、3T 和 7T 时氧化铁浓度与表观磁化率之间的关系；使用模拟评估亚体素血管的可视化能力；在 7T 下（剂量为 1mg/kg 至 4mg/kg）对 3 名健康志愿者进行了使用氧化铁增强小血管可视性的可行性确认。由两名评估者评估纹状体动脉和髓质静脉的可视化，并测量这些血管的对比噪声比（CNR）。
7T 时，氧化铁浓度与磁化率呈线性关系，斜率为 13.3 ± 0.2 ppm·mg ·mL。模拟表明，SWI 数据增加氧化铁剂量、更高的回波时间（TE）和更高的成像分辨率可以提高对较小血管的检测。使用 4mg/kg 氧化铁，体素长宽比= 1:8，TE = 10ms，最小可检测动脉的直径约为 50μm。体内数据的动脉评分从 1.5 ± 0.5（预对比）提高到 3.0 ± 0.0（4mg/kg 后），动脉的表观磁化率（4mg/kg 时为 0.65 ± 0.02ppm）与预期的磁化率（0.71 ± 0.05ppm）吻合良好。
使用 SWI 可以增强氧化铁对脑血管的 CNR，使用 QSM 可以可靠地定量测量动脉的表观磁化率。这种方法改善了毛细血管外整个血管系统的成像，可能对涉及微血管的各种神经退行性疾病具有重要价值。
1 技术功效：阶段 1 J. Magn. Reson. Imaging 2018;47:621-633.
