الفهرس 
HISTORY OF THREE-DIMENSIONAL IMAGINGOnly 14 pages are availabe for public view
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Abstract
Recently, the evaluation of the posterior fossa of the fetal cranium has been accepted as a part of the routine obstetric ultrasonographic examination. With this evaluation, structural anomalies in the central nervous system such as; Arnold-Chian malformations and Dandy-Walker malformations can be detected. Accurate assessment of the fetal organ dimensions by prenatal ultrasound is very crucial in the evaluation of fetal growth and maturation (Chitty et al., 1994a, 1994b, 1994c).
However, using two dimensional U/S to precisely assess the growth of small organs, such as cerebellum, is not an easy task, the fetal cerebellum is scanned now for screening the central nervous system anomaly (Benacerrof et al., 1989; Persutte et al., 1997; Robins et al., 1998) and for calculating the gestational age (Goldstein et al., 1987).
In fact, to measure the accurate “largest” diameter of fetal cerebellum in an attempt to determine the cerebellar transverse diameter in utero is relatively difficult by two-dimensional U/S. Because the fetal cerebellum is a small organ with a unique shape, to measure TCD of cerebellum by 2-D U/S is prone to substantial errors if the accurate plane for the measurement of TCD is not reached (Goldstein et al., 1987).
With the advent of three-dimensional (3-D) U/S, it becomes an easy technique to access any possible views and planes whenever the scanned 3-D volume is obtained (Kelly et al., 1992; Riccabona et al., 1996).
Moreover, precise quantitative measurement of fetal organ dimensions becomes feasible when the 3-D volume is retrieved (Lee et al., 1994; Merze et al., 1995; Ricabonna et al., 1996).
As the size of the fetal cerebellum or TCD is also important because it is a useful biometric parameters in estimating gestational age specially in the second trimesters, and 3-D U/S can overcome the obstacle of 2-D U/S in reaching the accurate plane for measuring fetal cerebellar dimensions; this study was to establish the normal growth charts of fetal transverse cerebellar diameter and cerebellar volume during gestation, using this new modality of 3-D U/S.
The current study was conducted at Ain Shams University Maternity Hospital during the period from September 2009 to August 2010. It was conducted on (125) pregnant women. These patients were between 23-34 years old, the mean age was 28.66 + 3.54 years. The median parity was (range: 0-3; interquartile range 1-2).
The mean gestational age at recruitment was 24.46 + 0.3 weeks (range: 24 + 24.86 weeks).
Obstetric 2D ultrasonography was performed to all included women for measuring fetal biometry including biparietal diameter BPD, head circumference HC, abdominal circumference AC, femur length FL, as well as transverse cerebellar diameter TCD. Fetal weight was estimated using the Hadlock’s formula.
In addition, 3D U/S was performed for all included women for measuring cerebellar volume (using VOCAL method) when this methodology has compared to multiplanar method, it has the advantages of allowing the modification of the outline of the organ, which is of irregular shape; such as fetal cerebellum.
By using the VOCAL (virtual organ computer-aided analysis) the results of this study showed that:
a- The mean cerebellar volume at recruitment was 2.91 + 0.31cm3.
b- Cerebellar volume had a significant positive correlation with both EFW and gestational age.
c- Cerebellar volume had a strong significant positive correlation with each of the fetal biometry measures including BPD, FL, HC, AC, and TCD.
d- All measures of fetal biometry had strong significant positive correlations with both EFW and gestational age.
e- FL, AC &EFW were altered in cases of IUGR as shown in group 1(LBW)