Lätt J, Nilsson M, van Westen D, Wirestam R, Ståhlberg F, Brockstedt S
Department of Medical Radiation Physics, Lund University, Lund, Sweden.
NMR Biomed. 2009 Jul;22(6):619-28. doi: 10.1002/nbm.1376.
The aim of this study was to investigate the diffusion time dependence of signal-versus-b curves obtained from diffusion-weighted magnetic resonance imaging (DW-MRI) of sub-acute ischaemic lesions in stroke patients. In this case series study, 16 patients with sub-acute ischaemic stroke were examined with DW-MRI using two different diffusion times (60 and 260 ms). Nine of these patients showed sufficiently large lesions without artefacts to merit further analysis. The signal-versus-b curves from the lesions were plotted and analysed using a two-compartment model including compartmental exchange. To validate the model and to aid the interpretation of the estimated model parameters, Monte Carlo simulations were performed. In eight cases, the plotted signal-versus-b curves, obtained from the lesions, showed a signal-curve split-up when data for the two diffusion times were compared, revealing effects of compartmental water exchange. For one of the patients, parametric maps were generated based on the extracted model parameters. These novel observations suggest that water exchange between different water pools is measurable and thus potentially useful for clinical assessment. The information can improve the understanding of the relationship between the DW-MRI signal intensity and the microstructural properties of the lesions.
本研究旨在探讨中风患者亚急性缺血性病变的扩散加权磁共振成像（DW-MRI）中，信号- b曲线的扩散时间依赖性。在这个病例系列研究中，对16例亚急性缺血性中风患者使用两种不同的扩散时间（60和260毫秒）进行了DW-MRI检查。其中9例患者显示出足够大的无伪影病变，值得进一步分析。绘制病变的信号- b曲线，并使用包含隔室交换的双室模型进行分析。为了验证模型并辅助解释估计的模型参数，进行了蒙特卡罗模拟。在8例病例中，当比较两个扩散时间的数据时，从病变获得的绘制信号- b曲线显示出信号曲线分离，揭示了隔室水交换的影响。对于其中一名患者，基于提取的模型参数生成了参数图。这些新发现表明，不同水池之间的水交换是可测量的，因此可能对临床评估有用。该信息可以增进对DW-MRI信号强度与病变微观结构特性之间关系的理解。
