兔肝脏3．0T磁共振弥散加权成像的实验研究

An Experimental Study on Rabbit Liver by 3.0 Tesla Magnetic Resonance Diffusion-weighted Imaging

目的探索正常兔肝脏3.0T磁共振弥散加权成像(DWI)检查方法学及兔正常肝脏DWI特征、量化指标和参考标准。方法雄性新西兰大白兔20只,用速眠新Ⅱ注射液麻醉后,采用不同b值分别行DWI扫描。以表观弥散系数(ADC)值及其最大值与最小值的差值、信号强度(SH)、噪声(SD)、信噪比(SNR)、质量指数(QI)为指标进行统计学分析。结果随着b值的增大,肝实质平均ADC值逐渐变小,差异有统计学意义(P<0.001)。ADC值的最大值与最小值的差值,以b=1000 s/mm2时最小,b=300 s/mm2时最大。SH值随b值的增大而逐渐变小(P<0.001),当b=600、800、1000 s/mm2时三者差异无统计学意义(P>0.05)。SD值随b值的增大而逐渐变小(P<0.001),b=800、1000 s/mm2时两者差异无统计意义(P>0.05)。SNR值随b值的增大而逐渐变小(P<0.001),b=600 s/mm2时分别与b=800、1000 s/mm2时比较,差异无统计学意义(P>0.05)。QI值亦随b值的增大逐渐变小(P<0.001),b=800、1000 s/mm2时两者差异无统计学意义(P>0.05)。结论在兔肝脏3.0T超高场强磁共振DWI中,采用600 s/mm2的b值可以减少扫描时间,并保证一定的弥散权重、较好的图像质量和ADC值测量的稳定性。

To explore the methodology as well as the features, quantificational index, and reference standard of 3.0 Tesla magnetic resonance （MR） diffusionweighted imaging （DWI） on the normal rabbit＇s liver. Methods Twenty New Zealand white rabbits were enrolled and DWI was performed after anesthetics with multib values at 3.0T MR scanner. Apparent diffusion coefficient （ ADC ） values as well asthe difference between maximum and minimum ADC values, signal strength （SH）, noise signal （SD）, signal to noise ratio （ SNR）, and quality index （QI） were recorded and analyzed. Results With b value increased, the ADC values decreased accordingly （P 〈 0. 001 ）. The difference between maximum and minimum ADC values with b = 1000 s/mm2 was the least （good stability）, b = 600 s/mm2 was the second least, and b = 300 s/mm= was greatest （ bad stability）. The SH decreased at the same time （P 〈 0. 001 ）, but the difference among DWI with b = 600, 800, and 1000 s/mm2 was not statistically significant （ P 〉 0.05 ）. The SD decreased at the same time （ P 〈 0.001 ） , but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm2 was not statistically significant （ P 〉 0. 05 ）. The SNR decreased at the same time （P 〈 0. 001 ）, but there were no signif- icant differences between DWI with b = 600 s/mm2 and b = 800 s/mm2 or b = 600 s/mm2 and b = 1000 s/mm2 （ P 〉 0. 05 ）. The SNR of DWI with b = 800 s/mm2 and b = 1000 s/mm2 was lower. The QI decreased at the same time （ P 〈 0. 001 ）, but the difference between DWI with b = 800 s/mm2 and b = 1000 s/mm2 was not statistically significant （ P 〉 0.05 ）. Conclusion When 3.0T MR DWI is applied for rabbit liver, it is better to use b = 600 s/mm2 for reducing scanning time and assuring better diffusion weights, quantity of images, and stability of ADC measurement.