Aim
We purpose in this paper to precise the reliability of femoral and tibial lengths measurement on bi and three dimensional computed tomography reconstructions in fetal age estimation. We also compare the obtained results to determine which type of reconstruction is most reliable in terms of fetal age estimation.
Materiel and methods
Thirty-six female fetuses between 24 and 48 weeks of gestational age were included in our study. All selected fetuses were considered as normal. We realize for all fetuses a transverse computed tomography (CT) slices of 0.2 mm. Amira 4.0 program was used to generate bi- and three-dimensional CT reconstructions (2D/3D). We measure, respectively on 2D and 3D CT reconstruction, femoral and tibial lengths. We made a comparison between the results obtained by every type of realized reconstruction (2D or 3D).
Results
The difference between measures made in 3D and in 2D CT reconstructions is minor (0.87-1.38 mm). This difference is not statistically significant. It exist a good correlation between the measurements taken in 3D and in 2D CT reconstructions (correlation coefficient varies between 0.991 and 0.996). There is an excellent correlation between estimated age using Adalian and al formula and chronological age (correlation coefficient varies between 0.944 and 0.965). The application of Wilcoxon test shows that the median of difference does not exceed in absolute value 1.52 week of gestational age.
Conclusion
Fetal age estimation can be made using 2D or 3D CT reconstruction. However, in practice, taking measures in 3D CT reconstruction is easier by offering a good image for bone studying.