Prenatal Diagnosis Of Fetal Congenital Urinary Tract Abnormalities By MRI

Objective Magnetic resonance imaging(MRI)and anatomical histology were used to study the sensitivity of MRI in fetal kidney anatomy and the feasibility of quantitative evaluation of fetal kidney development.The qualitative diagnosis of fetal genitourinary abnormalities and quantitative evaluation were also discussed.Materials and Methods 1.Three pregnant sheep were selected from the 28 th to 36 th week of pregnancy.After the anesthesia,MRI were performed to analyze the fetal sheep.The MR showed the structural clarity of each system and organ,and the MRI examination sequences and methods were used for fetal system scanning.The focus is on the application of fetal urinary system.MRI data of 100 normal fetuses(16-38 weeks)were used to measure the length of the coronal and sagittal plane,and calculated the mean ADC value of the renal parenchyma,and the correlation between the length of the kidney and the ADC value with the gestational age was obtained,also the signal ratio of renal parenchyma to renal pelvis.2.Select 182 cases of fetal MRI with confirmed congenital genitourinary abnormalities after birth,and comparing fetal MRI and US with final results.Follow-up diagnosis including postnatal imaging(ultrasound,enhanced CT,MR urography),autopsy or surgery.Statistical analysis was performed using chi-square test and t test.Result 1.The basic contour of the fetal kidney and the structure of the renal hilum can be displayed at 21 weeks of gestation,and the boundary with the surrounding tissue is clear.The fetal RL measured by MRI was 13.52～43.08 mm,which was correlated with pregnancy.The mean ADC value of renal parenchyma was 1.18～3.2mm2/sec,which had a correlation with 16-30 pregnancy,there was no significant correlation between 31 and 38 weeks of pregnancy.2.In 182 cases of genitourinary abnormalities,29 cases had prenatal US diagnosis accuracy and MRI diagnosis was inaccurate,5 cases of US and MRI were not completely correct,US incomplete diagnosis was correct and MRI diagnosis was correct 4 cases,in addition,25 cases of oligohydramnios associated with the fetal lung dysplasia,prenatal US did not suggest.The difference in the accuracy of prenatal US and MRI in the diagnosis of urinary tract abnormalities is statistically significant.Conclusion MRI can better distinguish the structure of the urinary system during the middle and late pregnancy,without interference from maternal and fetal factors,and can dynamically quantify the development of the kidney.Compared with ultrasound,MRI has an advantage in the diagnosis of fetal genitourinary abnormalities,specifically quantifying kidney development and signal intensity.Fetal MRI can diagnose abnormalities earlier and more accurately with the combination of oligohydramnion and other urinary tract abnormalities.