摘要目的 探讨3.0-T MRI不同方向扩散梯度的正常胰腺表观扩散系数(ADC)直方图参数特征及差异.方法 回顾性分析21名胰腺正常的受试者3个单方向扩散梯度(X、Y、Z方向)与同时施加三正交方向扩散梯度的扩散加权成像(DWI)资料,基于自主开发的DWI后处理软件测量胰腺ADC均值、百分位数、偏度及峰度等直方图参数,利用Kruskal-Wallis方法比较4种扩散梯度获得的正常胰腺ADC直方图参数差异.结果 施加3个单方向扩散梯度与三正交方向扩散梯度获得的正常胰腺ADC平均值、偏度、百分位数等差异均无统计学意义,而峰度(X方向:3.16±1.44,Y方向:4.72±2.26,Z方向:4.47±2.1,正交方向:3.69±1.82)差异有统计学意义(χ2=-9.84,P=0.02).进一步分析结果表明X方向扩散梯度获得的正常胰腺ADC峰度小于Y、Z方向,差异有统计学意义(P<0.05).结论 正常胰腺ADC峰度与扩散梯度方向有关,X方向扩散梯度获得的正常胰腺ADC峰度最小.

abstractsObjective To investigate the characteristics of histogram analysis and differences of apparent diffusion coefficient ( ADC) for normal pancreas with different diffusion gradients of diffusion weighted imaging (DWI) at 3. 0T. Methods Three unidirectional diffusion gradients (X, Y or Z direction) and three orthogonal diffusion gradient DWI data of 21 volunteers with normal pancreas were retrospectively analyzed. The histogram parameters of mean ADC, percentile, skewness, peak and the like were measured based on home-made DWI post-processing software, and the differences on histogram parameters obtained from 4 different diffusion gradients were compared by using Kruskal Wallis test. Results There was no significant difference on the mean ADC, skewness, percentile and the like for normal pancreas among 3 unidirectional diffusion gradients and tri-orthogonal diffusion gradient DWIs, but there was significant difference on the mean kurtosis value ( X:3. 16 ± 1. 44, Y:4. 72 ± 2. 26, Z:4. 47 ± 2. 1, tri-orthogonal:3. 69 ± 1. 82; χ2 = -9. 84, P=0. 02). Further analyses results showed that the ADC kurtosis of normal pancreas obtained from X-directional diffusion gradient DWI was significantly smaller than that of the direction of Y or Z, and the difference was statistically significant (P<0.05). Conclusions The ADC kurtosis of normal pancreas is related to the direction of diffusion gradient in DWI, and the ADC kurtosis of normal pancreas obtained by X-direction diffusion gradient is the smallest.