Ropele S, Stollberger R, Hartung H P, Fazekas F
Department of Neurology, Karl-Franzens-University of Graz, A-8036 Graz, Austria.
J Magn Reson Imaging. 2000 Nov;12(5):749-56. doi: 10.1002/1522-2586(200011)12:5<749::aid-jmri13>3.0.co;2-2.
A new imaging method has been developed for estimating the magnetization transfer rate (MTR) in a biologic two-pool system such as the brain tissue. The transfer rate is calculated from the ratio of the MTR to T(1sat), where T(1sat) is the apparent longitudinal relaxation time under complete saturation of the macromolecular pool. MTR and T(1sat) maps were obtained with a phase acquisition of composite echo (PACE) technique combined with pulsed radiofrequency (RF) saturation. The influences of RF saturation power and frequency offset on quantitative results were investigated with phantom and in vivo measurements. In white matter of seven healthy volunteers we found a mean transfer rate of 1.5 sec(-1), where the highest transfer rate was found in the genu of the corpus callosum (k(f) = 1. 9 sec(-1)). It could be shown that conditions near to complete saturation can also be reached under common restrictions by the specific absorption rate.
已开发出一种新的成像方法，用于估计生物双池系统（如脑组织）中的磁化传递率（MTR）。传递率由MTR与T(1sat)的比值计算得出，其中T(1sat)是大分子池完全饱和时的表观纵向弛豫时间。通过复合回波相位采集（PACE）技术结合脉冲射频（RF）饱和获得MTR和T(1sat)图谱。利用体模和体内测量研究了RF饱和功率和频率偏移对定量结果的影响。在7名健康志愿者的白质中，我们发现平均传递率为1.5秒⁻¹，其中胼胝体膝部的传递率最高（k(f)=1.9秒⁻¹）。结果表明，在特定吸收率的常见限制下，也可以达到接近完全饱和的条件。
