The purposes of this study were to assess the fetal cerebellar volume during normal
gestation using three-dimensional (3-D) ultrasound (US) and to establish a normal
chart of fetal cerebellar volume using Altman's model of statistics. In total, 231
healthy fetuses were studied for assessment of cerebellar volume using a 3-D US volume
scanner. The fetuses to be studied were selected to give a cross-sectional series
(i.e., each fetus was examined only once). Polynomial regression analysis was calculated
to find the best-fit model using gestational age as the independent variable and cerebellar
volume as the dependent variable. Altman's model was used to calculate the age-related
reference centiles for the variance of cerebellar volume. In addition, common fetal
growth indices, such as biparietal diameter, occipitofrontal diameter, head circumference,
abdominal circumference, femur length and estimated fetal weight, were also measured
for the correlation between cerebellar volume and these indices. Our results indicated
that the fetal cerebellar volume was highly correlated with gestational age in normal
pregnancies with the best-fit polynomial regression equation of a second-order (r
= 0.91, p < 0.0001). In addition, fetal cerebellar volume in normal gestation is also
highly correlated with common fetal growth indices, such as biparietal diameter, occipitofrontal
diameter, head circumference, abdominal circumference, femur length and estimated
fetal weight (all p < 0.0001). Following the Altman's model, a normal growth chart
of fetal cerebellar volume was established for clinical reference. In conclusion,
with 3-D US, the assessment of fetal cerebellar volume becomes feasible. We believe
that fetal cerebellar volume assessed by 3-D US may be useful in detecting cerebellar
hypoplasia and relevant syndromes prenatally.