Center for Biomedical Engineering, Department of Electronic Science and Technology, University of Science and Technology of China, Hefei, China.
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.
Magn Reson Med. 2019 Jan;81(1):533-541. doi: 10.1002/mrm.27419. Epub 2018 Sep 9.
Diffusional kurtosis imaging (DKI) measures the deviation of the displacement probability from a normal distribution, complementing the data commonly acquired by diffusion MRI. It is important to elucidate the sources of kurtosis contrast, particularly in biological tissues where microscopic kurtosis (intrinsic kurtosis) and diffusional heterogeneity may co-exist.
We have developed a technique for microscopic kurtosis MRI, dubbed microscopic diffusional kurtosis imaging (µDKI), using a symmetrized double diffusion encoding (s-DDE) EPI sequence. We compared this newly developed µDKI to conventional DKI methods in both a triple compartment phantom and in vivo.
Our results showed that whereas conventional DKI and µDKI provided similar measurements in a compartment of monosphere beads, kurtosis measured by µDKI was significantly less than that measured by conventional DKI in a compartment of mixed Gaussian pools. For in vivo brain imaging, µDKI showed small yet significantly lower kurtosis measurement in regions of the cortex, CSF, and internal capsule compared to the conventional DKI approach.
Our study showed that µDKI is less susceptible than conventional DKI to sub-voxel diffusional heterogeneity. Our study also provided important preliminary demonstration of our technique in vivo, warranting future studies to investigate its diagnostic use in examining neurological disorders.
扩散峰度成像（DKI）测量位移概率从正态分布的偏差，补充扩散 MRI 通常采集的数据。阐明峰度对比的来源很重要，特别是在微观峰度（固有峰度）和扩散异质性可能共存的生物组织中。
我们使用对称双扩散编码（s-DDE）EPI 序列开发了一种微观峰度 MRI 技术，称为微观扩散峰度成像（µDKI）。我们在三重隔室模型和体内将新开发的 µDKI 与传统 DKI 方法进行了比较。
我们的结果表明，虽然传统的 DKI 和 µDKI 在单球珠隔间中提供了相似的测量值，但 µDKI 测量的峰度在混合高斯池隔间中明显小于传统 DKI 测量的峰度。对于活体脑成像，µDKI 在皮质、CSF 和内囊区域的测量值略小，但显著低于传统 DKI 方法。
我们的研究表明，µDKI 比传统 DKI 对亚体素扩散异质性的敏感性更低。我们的研究还在体内对我们的技术进行了重要的初步演示，值得进一步研究以调查其在检查神经疾病中的诊断用途。
