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.