High-resolution intracranial and cervical MRA at 3.OT: Technical considerations and initial experience
High-resolution intracranial and cervical MRA at 3.OT: Technical considerations and initial experience
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DOI：
10.1002/mrm.1282
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发表时间：
2001-11-01
影响因子：
3.3
通讯作者：
Felmlee, JP
中科院分区：
文献类型：
--
作者：
Bernstein, MA;Huston J, III;Felmlee, JP
报告了 3.0T 颅内和颈部 MRA 的初步经验。体模测量（针对松弛效应进行校正）显示相同几何头部线圈中的 S/N (3.0T) = 2.14 +/- 0.08 x S/N (1.5T)。开发了具有高阶自动匀场功能的 3.0T 3DTOF 颅内成像方案，并在 12 名动脉瘤患者中与 1.5T 3DTOF 进行了比较。两位放射科医生的比较显示，3.0T 在动脉瘤的可视化方面明显更好 (P < 0.001)。还检验了 3.0T 颈部和颅内对比增强 MR 血管造影 (CEMRA) 的可行性。当场强从1.5T增加到3.0T时，钆造影剂的弛豫率仅降低约4-7%。在 8 名患者中获得了宫颈 3.0T CEMRA，其中两名患者有可用于直接比较的 1.5T 研究。图像比较表明 3.0T 是颈部 CEMRA 的有利场强。使用单通道发射接收头或颈部线圈、25 mL 钆特醇丸剂以及采样效率为 66% 的 3D 脉冲序列，在 3.0T 下可轻松实现 0.62-0.73 mm(3) 的体素体积（不包括零填充）。这种空间分辨率可以使颅内动脉瘤、颈动脉夹层和包括溃疡在内的动脉粥样硬化疾病可视化。与 1.5T 相比，3.0T MRA 的潜在缺点是 SAR 和 T-2(*) 失相增加。图像比较表明，由于 T-2(*) 相移造成的信号损失不会比 1.5T 造成的问题严重得多。计算并讨论了 CEMRA 的 RIF 功率沉积对 TR 的依赖性。 (C) 2001 Wiley-Liss, Inc.
Initial experience with intracranial and cervical MRA at 3.0T is reported. Phantom measurements (corrected for relaxation effects) show S/N (3.0T) = 2.14 +/- 0.08 x S/N (1.5T) in identical-geometry head coils. A 3.0T 3DTOF intracranial imaging protocol with higher-order autoshimming was developed and compared to 1.5T 3DTOF in 12 patients with aneurysms. A comparison by two radiologists showed the 3.0T to be significantly better (P < 0.001) for visualization of the aneurysms. The feasibility of cervical and intracranial contrast enhanced MR angiography (CEMRA) at 3.0T is also examined. The relaxivity of the gadolinium contrast agent decreases by only about 4-7% when the field strength is increased from 1.5 to 3.0T. Cervical 3.0T CEMRA was obtained in eight patients, two of whom had 1.5T studies available for direct comparison. Image comparison suggests 3.0T to be a favorable field strength for cervical CEMRA. Voxel volumes of 0.62-0.73 mm(3) (not including zero-filling) were readily achieved at 3.0T with the use of a single-channel transmit-receive head or cervical coil, a 25 mL bolus of gadoteridol, and a 3D pulse sequence with a 66% sampling efficiency. This spatial resolution allowed visualization of intracranial aneurysms, carotid dissections, and atherosclerotic disease including ulcerations. Potential drawbacks of 3.0T MRA are increased SAR and T-2(*) dephasing compared to 1.5T. Image comparison suggests signal loss due to T-2(*) dephasing will not be substantially more problematic than at 1.5T. The dependence of RIF power deposition on TR for CEMRA is calculated and discussed. (C) 2001 Wiley-Liss, Inc.