Stokes Ashley M, Quarles C Chad
Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
Magn Reson Med. 2016 Jan;75(1):356-62. doi: 10.1002/mrm.25591. Epub 2015 Mar 5.
In this study, we propose a simplified acquisition and analysis approach for spin and gradient echo (SAGE)-based dynamic susceptibility-contrast MRI (DSC-MRI) data that is free of contrast agent T1 leakage effects.
A five-echo SAGE sequence was used to acquire DSC-MRI data in rat C6 tumors (n = 7). Nonlinear fitting of all echoes was performed to obtain T1-insensitive ΔR2* and ΔR2 time series. The simplified approach, which includes two gradient echoes and one spin echo, was also used to analytically compute T1-insensitive ΔR2* using the two gradient echoes and ΔR2 using all three echoes. The blood flow, blood volume, and vessel size values derived from each method were compared.
In all cases, the five-echo and simplified SAGE ΔR2* and ΔR2 were in excellent agreement and demonstrated significant T1 leakage correction compared with the uncorrected single-echo data. The derived hemodynamic parameters for blood volume, blood flow, and vessel size were not significantly different between the two methods.
The proposed simplified SAGE technique enables the acquisition of gradient and spin echo DSC-MRI data corrected for T1 leakage effects yields parameters that are in agreement with the five-echo SAGE approach and does not require nonlinear fitting to extract ΔR2* and ΔR2 time series.
在本研究中，我们提出了一种基于自旋和梯度回波（SAGE）的动态对比增强磁共振成像（DSC-MRI）数据的简化采集与分析方法，该方法不受造影剂T1泄漏效应的影响。
使用五回波SAGE序列在大鼠C6肿瘤（n = 7）中采集DSC-MRI数据。对所有回波进行非线性拟合以获得对T1不敏感的ΔR2和ΔR2时间序列。还使用包括两个梯度回波和一个自旋回波的简化方法，通过两个梯度回波解析计算对T1不敏感的ΔR2，并使用所有三个回波计算ΔR2。比较了每种方法得出的血流量、血容量和血管大小值。
在所有情况下，五回波和简化SAGE的ΔR2*和ΔR2都非常吻合，并且与未校正的单回波数据相比，显示出显著的T1泄漏校正。两种方法得出的血容量、血流量和血管大小的血流动力学参数没有显著差异。
所提出的简化SAGE技术能够采集针对T1泄漏效应校正的梯度和自旋回波DSC-MRI数据，得出与五回波SAGE方法一致的参数，并且不需要非线性拟合来提取ΔR2*和ΔR2时间序列。
