Wetzel S G, Lee V S, Tan A G, Heid O, Cha S, Johnson G, Rofsky N M
Department of Radiology, New York University Medical Center, 530 First Ave., HCC Basement-MRI, New York, NY 10016, USA.
AJR Am J Roentgenol. 2001 Sep;177(3):703-7. doi: 10.2214/ajr.177.3.1770703.
Real-time interactive duplex MR imaging is a new phase-contrast MR imaging technique that enables the quantification and display of flow velocities in real time without the need for cardiac gating. We investigated the feasibility and reliability of the technique to assess hemodynamic information both in vitro and in vivo in the carotid arteries and in the venous sinuses.
Real-time interactive duplex MR measurements (TR/TE, 53/27; flip angle, 90 degrees; encoding velocity, 100 or 150 cm/sec) were performed in vitro with a steady-flow phantom and in 10 healthy volunteers in whom common and internal carotid artery velocities were measured. In eight volunteers, velocity measurements were also performed in the superior sagittal sinus during both normal breathing and hyperventilation. Time-velocity plots were analyzed qualitatively and quantitatively and compared with findings from conventional segmented k-space phase-contrast MR imaging and Doppler sonography.
Velocity determinations for real-time duplex MR and conventional phase-contrast MR imaging showed an in vitro correlation of 0.99 and an in vivo correlation of 0.83 (carotid arteries) and 0.76 (venous sinus). Velocity measurements in the carotid arteries with real-time MR imaging were significantly lower than those obtained with conventional phase-contrast MR (averaged, 7.8%; p = 0.003) or sonography (23.7%, p < 0.001), likely because of volume averaging. Small but significant velocity changes occurring in the venous sinus during hyperventilation were reliably identified with both MR techniques.
Real-time interactive duplex MR imaging can be effectively applied in neurovascular imaging to obtain hemodynamic information.
实时交互式双平面磁共振成像（MR）是一种新的相位对比MR成像技术，可在无需心脏门控的情况下实时定量并显示血流速度。我们研究了该技术在体外和体内评估颈动脉及静脉窦血流动力学信息的可行性和可靠性。
使用稳流模型在体外进行实时交互式双平面MR测量（重复时间/回波时间，53/27；翻转角，90度；编码速度，100或150厘米/秒），并对10名健康志愿者进行测量，测定其颈总动脉和颈内动脉的血流速度。在8名志愿者中，还在正常呼吸和过度换气期间对上矢状窦进行了血流速度测量。对时间-速度图进行定性和定量分析，并与传统分段k空间相位对比MR成像及多普勒超声检查结果进行比较。
实时双平面MR与传统相位对比MR成像的速度测定结果在体外的相关性为0.99，在体内颈动脉的相关性为0.83，静脉窦的相关性为0.76。实时MR成像测定的颈动脉血流速度显著低于传统相位对比MR成像（平均低7.8%；p = 0.003）或超声检查（低23.7%，p < 0.001），这可能是由于容积平均效应所致。两种MR技术均能可靠地识别出过度换气期间静脉窦内发生的微小但显著的血流速度变化。
实时交互式双平面MR成像可有效地应用于神经血管成像以获取血流动力学信息。
