三维稳态进动快速成像和扩散加权成像评估胎儿肾脏发育状况的价值

Study of MRI with three-dimensional fast imaging employing steady-state acquisition and diffusion weighted imaging in the evaluation of fetal renal development

目的：探讨三维稳态进动快速成像（3D-FIESTA）和DWI评估胎儿肾脏发育状况的价值。方法回顾性分析2014年1月至2015年1月产前超声检查发现异常，并排除泌尿系统异常和MRI禁忌证的单胎妊娠胎儿107例，所有胎儿均行MRI检查，3D-FIESTA序列图像经过MPR重组后，测量胎儿肾脏的长度及厚度；在DWI序列的ADC图上测量ADC值。双肾各测量值采用配对样本t检验进行比较，各测量值与孕周的关系采用一元线性回归分析，并采用配对样本t检验将9例肾积水与相同孕周的正常肾脏各测量值进行比较。结果正常胎儿双肾各测量值差异均无统计学意义。肾脏平均长度（L）和平均厚度（T）分别为（31.09±6.13）、（6.69±1.50）mm。两者与孕周（G）均呈线性正相关，回归方程分别为L（mm）=1.242×G（周）－4.284（R2=0.86，P〈0.01）；T（mm）=0.256×G（周）－0.609（R2=0.62， P〈0.01）。正常胎儿肾脏平均ADC值为（1.48±0.14）×10-3 mm2/s，与孕周呈线性负相关，回归方程为ADC （×10-3mm2/s）=2.175－0.025×G（周）（R2=0.65，P〈0.01）。肾积水胎儿肾脏增大，实质变薄，ADC值高于相同孕周的正常胎儿肾脏，差异有统计学意义（P〈0.01）。结论3D-FIESTA能准确测量胎儿肾脏实质范围，结合DWI的ADC值测量能帮助产前胎儿肾脏异常的诊断。

Objective To explore the value of three-dimensional fast imaging employing steady-state acquisition（3D-FIESTA） and DWI in the evaluation of fetal renal development. Methods From January 2014 to January 2015, 107 consecutive singleton fetuses （gestational age range 21—38 weeks） underwent 1.5 T MRI after exclusion of urinary system malformation using ultrasound . The maximum renal length was measured on oblique sagittal MPR image of 3D-FIESTA sequences, and thickness was measured on axial MPR image. The ADC values were measured on ADC maps. Statistical analysis of measurements in the right and left kidney was performed with paired-samples t-test, and simple linear regression used to evaluate the relationship between the mean values and gestational age. The measurements in 9 hydronephrotic fetuses （gestational age range 21—35 weeks） were compared with those with normal fetal kidneys and the same gestational age by paired-samples t-test. Results No statistically significant differences were observed for all the measurements between the left and right kidney. The average length and thickness of normal kidneys were （31.09±6.13）,（6.69±1.50） mm, respectively. They correlated positively with gestation age. The regression equation for kidney length （L） （mm） and gestational age （G） （w） was L=1.242×G-4.284（R2=0.86,P〈0.01）. The regression equation for kidney thickness （T） （mm） and gestational age （G） （w） was T=0.256×G-0.609 （R2=0.62,P〈0.01）. The mean value of ADC was （1.48±0.14）×10-3 mm2/s and it decreased with gestational age. The regression equations was ADC=2.175-0.025 × G（R2=0.65, P〈0.01）, the enlarged kidneys and thinned parenchyma were detected in hydronephrotic kidneys with ADC values higher than normal kidney significantly（P〈0.01）. Conclusion 3D-FIESTA and DWI can evaluate fetal renal parenchyma and aid the antenatal diagnosis of renal pathology by defining renal size and ADC values.