Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
Department of Bioengineering, University of California-San Diego, La Jolla, California, USA.
Magn Reson Med. 2017 Sep;78(3):1174-1186. doi: 10.1002/mrm.26466. Epub 2016 Sep 26.
The diffusion tensor model assumes Gaussian diffusion and is widely applied in cardiac diffusion MRI. However, diffusion in biological tissue deviates from a Gaussian profile as a result of hindrance and restriction from cell and tissue microstructure, and may be quantified better by non-Gaussian modeling. The aim of this study was to investigate non-Gaussian diffusion in healthy and hypertrophic hearts.
Thirteen rat hearts (five healthy, four sham, four hypertrophic) were imaged ex vivo. Diffusion-weighted images were acquired at b-values up to 10,000 s/mm . Models of diffusion were fit to the data and ranked based on the Akaike information criterion.
The diffusion tensor was ranked best at b-values up to 2000 s/mm but reflected the signal poorly in the high b-value regime, in which the best model was a non-Gaussian "beta distribution" model. Although there was considerable overlap in apparent diffusivities between the healthy, sham, and hypertrophic hearts, diffusion kurtosis and skewness in the hypertrophic hearts were more than 20% higher in the sheetlet and sheetlet-normal directions.
Non-Gaussian diffusion models have a higher sensitivity for the detection of hypertrophy compared with the Gaussian model. In particular, diffusion kurtosis may serve as a useful biomarker for characterization of disease and remodeling in the heart. Magn Reson Med 78:1174-1186, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
扩散张量模型假设扩散符合高斯分布，被广泛应用于心脏扩散磁共振成像。然而，生物组织中的扩散由于受到细胞和组织微观结构的阻碍和限制，偏离了高斯分布，可以通过非高斯建模更好地进行量化。本研究旨在研究健康和肥厚心脏中的非高斯扩散。
对 13 只大鼠心脏（5 只健康，4 只假手术，4 只肥厚）进行离体成像。在 b 值高达 10,000 s/mm 的范围内采集扩散加权图像。根据赤池信息量准则对数据进行拟合和排名。
在 b 值高达 2000 s/mm 的情况下，扩散张量模型的排名最高，但在高 b 值范围内对信号的反映较差，最佳模型是非高斯的“β分布”模型。尽管健康、假手术和肥厚心脏之间的表观扩散系数有很大的重叠，但肥厚心脏的板层和板层法向方向的扩散峰度和偏度分别高出 20%。
与高斯模型相比，非高斯扩散模型对检测肥厚有更高的灵敏度。特别是，扩散峰度可能是心脏疾病和重构特征的有用生物标志物。磁共振医学 78:1174-1186, 2017。© 2016 国际磁共振学会。
