Filli Lukas, Wurnig Moritz, Nanz Daniel, Luechinger Roger, Kenkel David, Boss Andreas
From the *Department of Diagnostic and Interventional Radiology, University Hospital of Zurich, and †Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland.
Invest Radiol. 2014 Dec;49(12):773-8. doi: 10.1097/RLI.0000000000000082.
Diffusion kurtosis imaging (DKI) is based on a non-Gaussian diffusion model that should inherently better account for restricted water diffusion within the complex microstructure of most tissues than the conventional diffusion-weighted imaging (DWI), which presumes Gaussian distributed water molecule displacement probability. The aim of this investigation was to test the technical feasibility of in vivo whole-body DKI, probe for organ-specific differences, and compare whole-body DKI and DWI results.
Eight healthy subjects underwent whole-body DWI on a clinical 3.0 T magnetic resonance imaging system. Echo-planar images in the axial orientation were acquired at b-values of 0, 150, 300, 500, and 800 mm²/s. Parametrical whole-body maps of the diffusion coefficient (D), the kurtosis (K), and the traditional apparent diffusion coefficient (ADC) were generated. Goodness of fit was compared between DKI and DWI fits using the sums of squared residuals. Data groups were tested for significant differences of the mean by paired Student t tests.
Good-quality parametrical whole-body maps of D, K, and ADC could be computed. Compared with ADC values, D values were significantly higher in the cerebral gray matter (by 30%) and white matter (27%), renal cortex (23%) and medulla (21%), spleen (101%), as well as erector spinae muscle (34%) (each P value <0.001). No significant differences between D and ADC were found in the cerebrospinal fluid (P = 0.08) and in the liver (P = 0.13). Curves of DKI fitted the measurement points significantly better than DWI curves did in most organs.
Whole-body DKI is technically feasible and may reflect tissue microstructure more meaningfully than whole-body DWI.
扩散峰度成像（DKI）基于非高斯扩散模型，与传统扩散加权成像（DWI）相比，该模型在解释大多数组织复杂微结构内受限水扩散方面本质上更具优势，传统DWI假定水分子位移概率呈高斯分布。本研究的目的是测试体内全身DKI的技术可行性，探究器官特异性差异，并比较全身DKI和DWI的结果。
8名健康受试者在临床3.0T磁共振成像系统上接受全身DWI检查。在b值为0、150、300、500和800mm²/s时采集轴向平面回波图像。生成扩散系数（D）、峰度（K）和传统表观扩散系数（ADC）的参数化全身图谱。使用残差平方和比较DKI和DWI拟合的拟合优度。通过配对学生t检验对数据组的均值进行显著性差异检验。
可以计算出高质量的D、K和ADC参数化全身图谱。与ADC值相比，D值在脑灰质（高30%）、白质（高27%）、肾皮质（高23%）、肾髓质（高21%）、脾脏（高101%）以及竖脊肌（高34%）中显著更高（每个P值<0.001）。在脑脊液（P = 0.08）和肝脏（P = 0.13）中未发现D和ADC之间的显著差异。在大多数器官中，DKI曲线比DWI曲线对测量点的拟合效果显著更好。
全身DKI在技术上是可行的，并且可能比全身DWI更有意义地反映组织微结构。
