Abstract Objective: To investigate the value of MRI in the prenatal diagnosis of abnormal fetal urinary tract. Methods: Forty-six fetuses with suspected urinary anomalies detected by routine ultrasound screening were rescanned by MRI to refine the diagnosis. All examined fetuses are single fetuses. The pregnancy outcome was examined externally by postnatal ultrasonography or MRI. Results: The average gestational age of 46 pregnant women was 28 weeks(range 20~39) and the mean maternal age was 26 years(range 21~40). Among 46 fetuses with congenital urinary system abnormalities, 30 cases had normal amniotic fluid volume(normal amniotic fluid group) and 16 cases had oligohydramnios(oligohydramnios group). The ratio of lung signal intensity to liver signal intensity(LLSIR) of oligohydramnios grpup was assessed by MRI to determine if there was fetal lung dysplasia. MRI diagnosis changed the preceding US diagnosis in 5 cases and added information in 12 cases. MRI confirmed US diagnosis in 4 fetuses. The prenatal US diagnosis was accurate and MRI diagnosis was incorrect in 2 cases, and prenatal US and MRI diagnosis were both not correct in 1 case. MRI showed 93.5%(43/46) accuracy in diagnosis while US showed 73.9%(34/46) accuracy. Oligohydramnios group were all complicated with pulmonary dysplasia and had a mean LLSIR of 1.01～1.87 and was obviously less than that in normal fetuses of similar gestational age(P=0.000<0.05). Conclusion: MRI is valuable in evaluating suspected fetal urinary tract abnomalies, especially when ultrasound is inconclusive owing to oligohydramnios.
SHANG Hong-lei,ZHAO Xin,ZHANG Xiao-an, et al. Application of MRI in fetal urinary system malformation[J]. JOURNAL OF CHINA MEDICAL IMAGING, 2019, 30(7): 499-502.
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