Tozer D, Ramani A, Barker G J, Davies G R, Miller D H, Tofts P S
NMR Research Unit, Department of Neuroinflammation, Institute of Neurology, University College London, London, UK.
Magn Reson Med. 2003 Jul;50(1):83-91. doi: 10.1002/mrm.10514.
Quantitative analysis of magnetization transfer images has the potential to allow a more thorough characterization of the protons, both bound and free, in a tissue by extracting a number of parameters relating to the NMR properties of the protons and their local environment. This work develops previously presented techniques to produce estimates of parameters such as the bound proton fraction, f, and the transverse relaxation time of the bound pool, T(2B), for the whole brain in a clinically acceptable imaging time. This is achieved by limiting the number of data collected (typically to 10); to collect 28 5-mm slices with a reconstructed resolution of 0.94 x 0.94 mm. The protocol takes 82 sec per data point. The fitting technique is assessed against previous work and for fitting failures. Maps and analysis are presented from a group of seven controls and 20 multiple sclerosis patients. The maps show that the parameters are sensitive to tissue-specific differences and can detect pathological change within lesions. Statistically significant differences in parameters such as T(2B) and f are seen between normal-appearing white matter, multiple sclerosis lesions, and control white matter. Whole-brain histograms of these parameters are also presented, showing differences between patients and controls.
通过提取一些与质子的核磁共振特性及其局部环境相关的参数，磁化传递图像的定量分析有潜力更全面地表征组织中结合态和游离态的质子。这项工作改进了之前提出的技术，以便在临床可接受的成像时间内，对全脑的参数进行估计，如结合质子分数f和结合池的横向弛豫时间T(2B)。这是通过限制采集的数据数量（通常为10个）来实现的；采集28个5毫米厚的切片，重建分辨率为0.94×0.94毫米。该方案每个数据点需要82秒。将该拟合技术与之前的工作进行了对比评估，并分析了拟合失败的情况。展示了一组7名对照者和20名多发性硬化症患者的图谱及分析结果。图谱显示，这些参数对组织特异性差异敏感，能够检测病变内的病理变化。在正常外观的白质、多发性硬化症病变和对照白质之间，观察到T(2B)和f等参数存在统计学上的显著差异。还展示了这些参数的全脑直方图，显示了患者与对照者之间的差异。
