The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
Magn Reson Med. 2018 Apr;79(4):2014-2023. doi: 10.1002/mrm.26864. Epub 2017 Aug 10.
To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage.
Tissue suppression using velocity-selective saturation (VSS) pulse trains is sensitive to radiofrequency field (B +) inhomogeneity. To reduce its sensitivity, we replaced the low-flip-angle hard pulses in the VSS pulse train with optimal composite (OCP) pulses. Additionally, new pulse sequences for arteriography and venography were developed by placing spatially selective inversion pulses with a delay to null signals from either venous or arterial blood. The VS MRA techniques were compared to the time-of-flight (TOF) MRA in six healthy subjects and two patients at 3T.
More uniform suppression of stationary tissue was observed when the hard pulses were replaced by OCP pulses in the VSS pulse trains, which improved contrast ratios between blood vessels and tissue background for both arteries (0.87 vs. 0.77) and veins (0.80 vs. 0.59). Both arteriograms and venograms depicted all major cervical and intracranial arteries and veins, respectively. Compared to TOF MRA, VS MRA not only offers larger spatial coverage but also depicts more small vessels. Initial clinical feasibility was shown in two patients with comparisons to TOF protocols.
Noncontrast-enhanced whole-brain arteriography and venography can be obtained without losing sensitivity to small vessel detection. Magn Reson Med 79:2014-2023, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
开发具有全脑覆盖范围的血管造影和静脉造影的速度选择（VS）MR 血管造影（MRA）协议。
使用速度选择饱和（VSS）脉冲序列进行组织抑制对射频场（B +）不均匀性敏感。为了降低其灵敏度，我们用最佳复合（OCP）脉冲替换 VSS 脉冲序列中的低翻转角硬脉冲。此外，通过放置具有延迟以消除静脉或动脉血液信号的空间选择性反转脉冲，为血管造影和静脉造影开发了新的脉冲序列。在 3T 下，将 VS MRA 技术与时间飞跃（TOF）MRA 比较了六名健康受试者和两名患者。
在 VSS 脉冲序列中用 OCP 脉冲替换硬脉冲时，观察到静止组织的抑制更加均匀，这提高了血管和组织背景之间的对比度比值，无论是动脉（0.87 对 0.77）还是静脉（0.80 对 0.59）。动脉造影和静脉造影分别描绘了所有主要的颈内和颅内动脉和静脉。与 TOF MRA 相比，VS MRA 不仅提供了更大的空间覆盖范围，而且还描绘了更多的小血管。在两名患者中与 TOF 方案进行比较，初步显示了临床可行性。
在不降低对小血管检测灵敏度的情况下，可以获得非对比增强的全脑动脉造影和静脉造影。磁共振医学 79：2014-2023，2018。© 2017 国际磁共振学会。
