Deoni Sean C L
Centre for Neuroimaging Research, Institute of Psychiatry, King's College London, London UK.
J Magn Reson Imaging. 2007 Oct;26(4):1106-11. doi: 10.1002/jmri.21130.
To investigate an alternative approach to correct for flip angle inaccuracies in the driven equilibrium single pulse observation of T1 (DESPOT1) T1 mapping method.
While DESPOT1 is a robust method for rapid whole-brain voxelwise mapping of the longitudinal relaxation time, the approach is inherently sensitive to inaccuracies in the transmitted flip angle, defined by the B1 field, which become more severe with increased field. Here we propose an extension of the DESPOT1 technique, involving the additional acquisition of an inversion-prepared SPGR image alongside the conventional multiangle DESPOT1 data. From these combined data both B1 and T1 may be determined with high accuracy and precision. The method is evaluated at 3T with phantom and in vivo imaging experiments, with derived T1 estimates compared with values calculated from multiple inversion time inversion recovery data.
The method provides robust correction of flip angle variations, with less than 5% error compared with reference values for T1 between 300 msec and 2500 msec.
The described approach, dubbed DESPOT1-HIFI, permits whole-brain T1 mapping at 3T, with 1 mm(3) isotropic voxels, in a clinically feasible time (approximately 10 minutes) with T1 accuracy greater than 5% and with high precision.
研究一种校正驱动平衡单脉冲T1观测法（DESPOT1）T1映射方法中翻转角不准确的替代方法。
虽然DESPOT1是一种用于全脑纵向弛豫时间快速体素映射的稳健方法，但该方法对由B1场定义的传输翻转角的不准确固有敏感，随着场强增加这种情况会变得更严重。在此，我们提出一种DESPOT1技术的扩展方法，即在传统多角度DESPOT1数据采集的同时额外采集反转准备的扰相梯度回波（SPGR）图像。从这些组合数据中可以高精度和高准确度地确定B1和T1。该方法在3T条件下通过体模和体内成像实验进行评估，将推导得到的T1估计值与从多个反转时间反转恢复数据计算得到的值进行比较。
该方法能稳健校正翻转角变化，与300毫秒至2500毫秒T1的参考值相比，误差小于5%。
所描述的方法，称为DESPOT1-HIFI，允许在3T条件下以1立方毫米各向同性体素进行全脑T1映射，在临床可行的时间内（约10分钟），T1准确度大于5%且精度高。
