正常胰腺扩散加权成像不同方向扩散梯度表观扩散系数直方图分析

Histogram analyses of apparent diffusion coefficients with different diffusion gradients in diffusionweightedimaging of normal pancreas

目的探讨3.0-TMR I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(x2=-9.84,/>=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。

Objective T o in v e s tig a te th e c h a r a c te r is tic s o f h isto g ra m a n a ly s is a n d d if fe r e n c e s o f a p p a r e n t d iffu s io n c o e f f ic ie n t(A D C)fo r n o rm a l p a n c r e a s w ith d iffe re n t d iffu sio n g r a d ie n ts o f d iffu s io n w e ig h te d im a g in g(D W I)a t 3.0 T.Methods T h re e u n id ire c tio n a l d iffu sio n g ra d ie n ts(X,Y o r Z d i r e c t i o n)a n d th r e e o rth o g o n a l d iffu s io n g r a d ie n t D W I d a ta o f 21 v o lu n te e r s w ith n o rm a l p a n c r e a s w ere r e tro s p e c tiv e ly a n a ly z e d.T h e h isto g ra m p a r a m e te r s o f m e a n A D C,p e r c e n t i l e,s k e w n e s s,p e a k a n d th e lik e w e re m e a s u re d b a s e d o n h o m e m a d e D W I p o s t-p r o c e s s in g so f tw a r e,a n d th e d iffe re n c e s o n h isto g ra m p a r a m e te r s o b ta in e d fro m 4 d iffe re n t d iffu s io n g r a d ie n ts w e re c o m p a re d by u s in g K r u s k a l W a llis te s t.Results T h e re w a s n o s ig n if ic a n t d iffe re n c e o n th e m e a n A D C,s k e w n e s s,p e r c e n tile a n d th e lik e fo r n o rm a l p a n c r e a s a m o n g 3 u n id ir e c tio n a l d iffu sio n g r a d ie n ts a n d tr i-o rth o g o n a l d iffu s io n g r a d ie n t D W I s,b u t th e r e w as sig n ific a n t d if fe r e n c e o n th e m e a n k u rto s is v a l u e(X:3.16±1.44,Y:4.72±2.26,Z:4.47±2.1,t r i-o r t h o g o n a l:3.69±1.82;x 2=-9.84,0.02).F u r th e r a n a ly s e s r e s u lts sh o w ed th a t th e A D C k u r to s is o f n o rm al p a n c r e a s o b ta in e d fro m X-d ire c tio n a l d iffu s io n g r a d ie n t D W I w a s sig n ific a n tly s m a lle r th a n th a t o f th e d ire c tio n o f Y o r Z,a n d th e d if fe r e n c e w as s ta tis tic a lly sig n if ic a n t(P<0.05).Conclusions T h e A D C k u rto sis o f n o rm a l p a n c r e a s is r e la te d to th e d ir e c tio n o f d iffu s io n g r a d ie n t in D W I,a n d th e A D C k u r to s is o f n o rm a l p a n c r e a s o b ta in e d b y X-d ire c tio n d iffu s io n g r a d ie n t is th e s m a lle s t.