使用相位对比平衡稳态自由进动技术改进脑脊液流动测量。

Improved cerebrospinal fluid flow measurements using phase contrast balanced steady-state free precession.

作者信息

McCormack Erin J, Egnor Michael R, Wagshul Mark E

机构信息

Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8181, USA.

出版信息

Magn Reson Imaging. 2007 Feb;25(2):172-82. doi: 10.1016/j.mri.2006.09.023. Epub 2006 Nov 20.

Abstract

We present a demonstration of phase contrast balanced steady-state free precession (PC-bSSFP) for measuring cerebrospinal fluid (CSF) flow in the brain and spine, and a comparison of measurements obtained with this technique to conventional phase contrast using incoherent gradient echoes (PC-GRE). With PC-GRE sequences, CSF images suffer from low signal-to-noise ratio (SNR), due to short repetition times required for adequate temporal resolution, and the long relaxation time of CSF. Furthermore, CSF flow is often nonlaminar, causing phase dispersion and signal loss in PC-GRE images. It is hypothesized that PC-bSSFP can improve CSF flow measurements with its high SNR and insensitivity to turbulent flow effects. CSF images acquired from the two techniques were compared in 13 healthy volunteers. Three measures were used to objectively evaluate the PC-bSSFP sequence: the CSF flow percentage, defined as the percentage of the total CSF region exhibiting pulsatile flow, net stroke volume and SNR. Images acquired with PC-bSSFP demonstrated pulsatile CSF flow in 35.8% (P<.005), 11.2% (P<.05) and 27.8% (P<.0005) more pixels than PC-GRE in the prepontine cistern, anterior and posterior cervical subarachnoid space (SAS), respectively. Likewise, measurements of stroke volume in these regions increased by 61.6% (P<.05), 16.8% (P<.001) and 48.3% (P<.0001), respectively. Similar comparisons in the aqueduct showed no statistical difference in stroke volumes between the two techniques (P=.5). The average gain in SNR was 3.3+/-1.7 (P<.001) in the prepontine cistern, 5.0+/-0.2 (P<.01) at the cervical level and 2.0+/-0.4 (P<.001) in the aqueduct in PC-bSSFP magnitude images over PC-GRE images. In addition to the obvious advantage of increased SNR, these results indicate that PC-bSSFP provides more complete measurements of CSF flow data than PC-GRE. PC-bSSFP can be used as a reliable technique for CSF flow quantification for the characterization of normal and altered intracranial CSF flow patterns.

摘要

我们展示了用于测量脑和脊柱中脑脊液(CSF)流动的相位对比平衡稳态自由进动(PC-bSSFP)技术,并将该技术获得的测量结果与使用非相干梯度回波的传统相位对比(PC-GRE)进行了比较。使用PC-GRE序列时,由于需要短重复时间以获得足够的时间分辨率,以及脑脊液的长弛豫时间,脑脊液图像的信噪比(SNR)较低。此外,脑脊液流动通常是非层流的,导致PC-GRE图像中的相位色散和信号损失。据推测,PC-bSSFP凭借其高SNR和对湍流效应的不敏感性,可以改善脑脊液流动测量。在13名健康志愿者中比较了两种技术获取的脑脊液图像。使用三种测量方法客观评估PC-bSSFP序列:脑脊液流动百分比,定义为显示搏动性流动的总脑脊液区域的百分比、净搏出量和SNR。与PC-GRE相比,PC-bSSFP获取的图像在前脑桥池、颈前和颈后蛛网膜下腔(SAS)中显示搏动性脑脊液流动的像素分别多35.8%(P<0.005)、11.2%(P<0.05)和27.8%(P<0.0005)。同样,这些区域的搏出量测量值分别增加了61.6%(P<0.05)、16.8%(P<0.001)和48.3%(P<0.0001)。在导水管中的类似比较显示,两种技术之间的搏出量没有统计学差异(P = 0.5)。与PC-GRE图像相比,PC-bSSFP幅度图像在前脑桥池的平均SNR增益为3.3±1.7(P<0.001),在颈椎水平为5.0±0.2(P<0.01),在导水管为2.0±0.4(P<0.001)。除了SNR增加的明显优势外这些结果表明,与PC-GRE相比,PC-bSSFP能提供更完整的脑脊液流动数据测量。PC-bSSFP可作为一种可靠的技术,用于脑脊液流动定量分析,以表征正常和改变的颅内脑脊液流动模式。

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