Kjaer L, Thomsen C, Henriksen O
Department of Magnetic Resonance, Hvidovre Hospital, University of Copenhagen, Denmark.
Acta Radiol. 1989 Jul-Aug;30(4):433-7.
Quantitative estimation of individual biologic components in relaxation curves obtained in vivo may increase the specificity of tissue characterization by magnetic resonance imaging. In this study, the potential of biexponential curve analysis was evaluated in T1 and T2 measurements on the human brain at 1.5 tesla. Optimal experimental conditions were carefully observed, including the use of long TR values and a very small voxel size. T1 determination was based on a 12-points partial saturation inversion recovery pulse sequence. T2 determination involved a multiple spin echo sequence with 32 echoes. No genuine biexponentiality was demonstrated in the T1 and T2 relaxation processes of white matter, cortical grey matter, or cerebrospinal fluid. Thus, a monoexponential model seems adequate for description of the relaxation behaviour in these cases. Furthermore, the results suggest that the accuracy of the measurements may not be critically dependent on the voxel size employed.
对体内获得的弛豫曲线中的各个生物成分进行定量估计，可能会提高磁共振成像组织表征的特异性。在本研究中，在1.5特斯拉磁场下对人脑进行T1和T2测量时，评估了双指数曲线分析的潜力。仔细观察了最佳实验条件，包括使用长TR值和非常小的体素大小。T1测定基于12点部分饱和反转恢复脉冲序列。T2测定涉及具有32个回波的多自旋回波序列。在白质、皮质灰质或脑脊液的T1和T2弛豫过程中未显示出真正的双指数特性。因此，单指数模型似乎足以描述这些情况下的弛豫行为。此外，结果表明测量的准确性可能并不严格依赖于所采用的体素大小。
