Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Magn Reson Imaging. 2009 Nov;30(5):1101-9. doi: 10.1002/jmri.21938.
To evaluate the feasibility of applying the shells trajectory to single-phase contrast-enhanced magnetic resonance angiography.
Several methods were developed to overcome the challenges of the clinical implementation of shells including off-resonance blurring (eg, from lipid signal), aliasing artifacts, and long reconstruction times. These methods included: 1) variable TR with variable readout length to reduce fat signal and off-resonance blurring; 2) variable sampling density to suppress aliasing artifacts while minimizing acquisition time penalty; and 3) an online 3D gridding algorithm that reconstructed an 8-channel, 240(3) image volume set. Both phantom and human studies were performed to establish the initial feasibility of the methods.
Phantom and human study results demonstrated the effectiveness of the proposed methods. Shells with variable TR and readout length further suppressed the fat signal compared to the fixed-TR shells acquisition. Reduced image aliasing was achieved with minimal scan time penalty when a variable sampling density technique was used. The fast online reconstruction algorithm completed in 2 minutes at the scanner console, providing a timely image display in a clinical setting.
It was demonstrated that the use of the shells trajectory is feasible in a clinical setting to acquire intracranial angiograms with high spatial resolution. Preliminary results demonstrate effective venous suppression in the cavernous sinuses and jugular vein region.
评估在单相对比增强磁共振血管造影中应用壳轨迹的可行性。
为了克服壳轨迹在临床应用中的挑战，开发了几种方法，包括离共振模糊（例如，来自脂质信号）、混叠伪影和长重建时间。这些方法包括：1）可变 TR 和可变读出长度以减少脂肪信号和离共振模糊；2）可变采样密度以抑制混叠伪影，同时最小化采集时间惩罚；3）在线 3D 网格算法，重建 8 通道、240（3）个图像体积集。进行了体模和人体研究，以建立该方法的初步可行性。
体模和人体研究结果证明了所提出方法的有效性。与固定 TR 壳采集相比，具有可变 TR 和读出长度的壳进一步抑制了脂肪信号。当使用可变采样密度技术时，通过最小化扫描时间惩罚来实现图像的混叠减少。快速在线重建算法在扫描器控制台中在 2 分钟内完成，在临床环境中提供及时的图像显示。
在临床环境中，使用壳轨迹来获取高空间分辨率的颅内血管造影是可行的。初步结果证明了在海绵窦和颈静脉区域有效抑制静脉。
