婴幼儿肾脏扩散加权成像b值和ADC值研究

Evaluation of B Value and Apparent Diffusion Coefficient by Diffusion Weighted Imaging of Kidney in Infants

目的探讨正常婴幼儿肾脏MRI扩散加权成像(DWI)扫描的最优b值。方法将30例4个月-23个月健康婴幼儿分成4组,分别以4种最大b值500s/mm2、700s/mm2、1000s/mm2和1500s/mm2行肾脏DWI序列扫描。使用随机区组方差分析,对四组肾实质的DWI图像质量评分、肾实质信号强度(SI)、信噪比(SNR)和在ADC图上测量的肾脏ADC值进行比较,P<0.05有统计学意义。结果四组b值下肾脏DWI图像质量、SI、SNR及ADC值的差异具有统计学意义。结论婴幼儿肾脏DWI检查最优b值为700s/mm2,灌注对扩散的影响相对较小,图像质量能够满足诊断要求,此时正常肾实质ADC值为(1.61±0.05)×10-3mm2/s。

Objective To investigate the optimal b value and normal ADC value of healthy infants in the kidney DWI examination. Methods Thirty healthy infants （ 4 months-23 months were examined with renal DWI on a 1.5T MR unit using b values including 500s/ mm^2, 700s/mm^2, 1000s/mm^2 and 1500s/mm^2.The picture quality, signal intensities（SI）, signal-to-noise ratio（SNR） on DWI were compared with the renal ADC value of normal parenchylna using analysis ofvariance（ANOVA）, P〈0.05. Results There was a statistically significant difference in picture quality, SI, SNR and ADC values of DWl among the four groups at different b values. Conclusion In our study, the optimal b values in evaluating the kidney of healthy infants is 700s/mm^2 and the mean ADC values of the normal infants＇ kidneys were（1.61 ± 0.05） × 10^-3mm^2/s at b=700s/mm^2, when b equals 700s/mm^2.