不同TE对兔肾磁敏感加权成像图像质量的影响

Effect of Echo Time on the Image Quality of Susceptibility Weighted Imaging in Rabbit Kidney

目的:探讨不同回波时间(TE)对兔肾二维(2D)磁敏感加权成像(SWI)的图像信噪比(SNR)的影响,选择适合兔肾SWI实验研究的成像参数。方法:15只健康新西兰大白兔行腹部MRI检查,应用TE为7.70ms、9.92ms、12.24ms三组SWI序列采集左肾图像。由两位放射科医师分析图像,比较三组SWI图像。结果:15只实验兔中2只实验兔因图像伪影明显予以剔除。TE7.70ms组、TE9.92ms组及TE12.24ms组SWI图像中,左肾实质的信号强度分别为399.41±47.63、362.16±48.86、356.21±15.40,三组SWI图像的SNR分别为20.48±2.27、19.12±2.29、16.54±2.36。TE7.70ms组和TE9.92ms组SW I图像的SN R均高于TE12.24ms组(P=0.007,P<0.001),TE7.70ms组与TE9.92ms组SWI图像的SNR之间无显著差异(P=0.140)。结论:应用2D SWI进行兔肾SWI实验研究时,选择适宜的TE为9.92ms可以获得理想的图像质量。

Purpose： To explore the correlation between echo time （TE） and SNR of susceptibility weighted imaging （SWI） in rabbit kidney, and to screen out feasible parameters for susceptibility weighted imaging in the research of rabbit kidneys. Methods： Fifteen healthy New Zealand rabbits underwent abdominal MRI scan and 2D SWI examination with different TEs （7.70ms, 9.92ms, 12.24ms） to acquire the images of the left kidneys of rabbits. Two experienced radiologists analyzed the images of SWI independently, and measured the SNR of the left kidney regions at the renal hilus planes. The intra-class correlation coefficient was used to evaluate the consistency between the two radiologists. The one-way ANOVA and LSD test was utilized to compare the SNR of SWI images among three different groups. Results： The images of two rabbits were rejected for obvious breathing motions. The results of the measurements on the three groups of SWI showed very good agreement between two radiologists （P〉0.800）. When TE=7.70ms was used, signal intensity （SI） of the left kidney on the SWI images was 399.41±47.63, SNR was 20.48±2.27; when TE=9.92ms was used, SI of the left kidney on the SWI images was 362.16±48.86, SNR was 19.12±2.29; and when TE=12.24ms was used, SI of the left kidney on the SWI images was 356.21±15.40, SNR was 16.54±2.36. SNR of the two groups （TE=7.70ms, TE=9.92ms） of SWI images were both higher than the third group （TE=12.24ms） （p=0.007, P〈0.001）. There was no statistically significant differences between the two groups （TE=7.70ms, TE=9.92ms） （p=0.140）. Conclusion： For the research of rabbit kidneys by 2D SWI, TE=9.92ms was feasible to acquire ideal image quality.