ABSTRACT
Objective:To explore the value of apparent diffusion coefficient (ADC) and renal volume in assessing fetal kidney development and disease.Methods:From January 2016 to October 2020, 84 fetuses with congenital anomalies of the kidney and urinary tract (CAKUT) were identified with MRI (CAKUT group), and 97 fetuses with no significant abnormalities on MRI or postnatal follow-up (control group) from the Obstetrics and Gynecology Hospital of Fudan University were enrolled and analyzed retrospectively. ADC value and renal volume were measured to compare the two groups, and the relationship was analyzed between these two parameters in the control group with gestational age, location (left or right kidney), and fetal gender. Two independent or paired sample t-tests, and linear correlation analyses, were adopted for the statistical analysis. Results:(1) There were 84 pregnant women in the CAKUT group, including a twin pregnancy, with an average age of (29±4) years old, ranging from 21 to 39 years old. The gestational age at MRI was (26±4) weeks with a range of 21-34 weeks. Of the 85 fetuses, 52 were male (61.2%), and 33 were female (38.8%). The polycystic dysplastic kidney was found in 32 cases (37.6%), hydronephrosis in 29 cases (34.1%), and an isolated kidney in 24 cases (28.2%). There were 97 singleton pregnancies in the control group, including 45 (46.4%) male and 52 (53.6%) female fetuses. The average maternal age was (30±5) years old, with a range of 19-41 years old, and the gestational week at MRI was (27±4) weeks, with a range of 21-34 weeks. (2) In the control group, the mean ADC value and renal volume were (1.255±0.112)×10 －3 mm2/s and (4 747±2 479) mm 3, which were negatively ( R 2=0.30, P<0.01) and positively correlated ( R 2=0.80, P<0.01) with the gestational age, respectively. There was no significant difference between ADC value and renal volume between different fetal gender in the control group. (3) The ADC value and the renal volume of fetuses with polycystic dysplastic kidney [(1.720±0.200) ×10 －3 mm2/s and (8 154±8 337) mm 3] were higher than those in the control group ( t=－13.11 and－3.08, P<0.001 and P=0.004). Compared with the control group, ADC of fetuses with hydronephrosis [(1.333±0.171) ×10 －3 mm2/s] was higher ( t=－3.90, P<0.001); and the renal volume [(7 201±4 460) mm 3] was larger but without statistical significance. The fetuses with an isolated kidney had an increasing trend in renal volume [(5 239±4 244) mm 3] and a decreasing trend in the ADC value [(1.239±0.125) ×10 －3 mm2/s] when compared with the normal fetuses, but neither difference was significant. Conclusions:In normal fetuses, the ADC value decreases, and the renal volume increases with the gestational age. Fetuses with CAKUT may have a larger kidney than normal.