Evaluation of Fetal First and Second Cervical Vertebrae: Normal or Abnormal?

Morphometric study of the neural ossification centers of the atlas and axis in the human fetus

Purposes

The knowledge of the developing cervical spine and its individual vertebrae, including their neural processes may be useful in the diagnostics of congenital vertebral malformations. This study was performed to quantitatively examine the neural ossification centers of the atlas and axis with respect to their linear, planar and volumetric parameters.

Methods

Using the methods of CT, digital-image analysis and statistics, the size of neural ossification centers in the atlas and axis in 55 spontaneously aborted human fetuses aged 17–30 weeks was studied.

Results

Without any male–female and right–left significant differences, the best fit growth dynamics for the neural ossification centers of the atlas and axis were, respectively, modelled by the following functions: for length: y = −13.461 + 6.140 × ln(age) ± 0.570 and y = −15.683 + 6.882 × ln(age) ± 0.503, for width: y = −4.006 + 1.930 × ln(age) ± 0.178 and y = −3.054 + 1.648 × ln(age) ± 0.178, for cross-sectional area: y = −7.362 + 0.780 × age ± 1.700 and y = −9.930 + 0.869 × age ± 1.911, and for volume: y = −6.417 + 0.836 × age ± 1.924 and y = −11.592 + 1.087 × age ± 2.509.

Conclusions

The size of neural ossification centers of the atlas and axis shows neither sexual nor bilateral differences. The neural ossification centers of the atlas and axis grow logarithmically in both length and width and linearly in both cross-sectional area and volume. The numerical data relating to the size of neural ossification centers of the atlas and axis derived from the CT and digital-image analysis are considered specific-age reference values of potential relevance in both the ultrasound monitoring and the early detection of spinal abnormalities relating to the neural processes of the first two cervical vertebrae in the fetus.

Digital image analysis of ossification centers in the axial dens and body in the human fetus

Purposes

The detailed understanding of the anatomy and timing of ossification centers is indispensable in both determining the fetal stage and maturity and for detecting congenital disorders. This study was performed to quantitatively examine the odontoid and body ossification centers in the axis with respect to their linear, planar and volumetric parameters.

Methods

Using the methods of CT, digital image analysis and statistics, the size of the odontoid and body ossification centers in the axis in 55 spontaneously aborted human fetuses aged 17–30 weeks was studied.

Results

With no sex difference, the best fit growth dynamics for odontoid and body ossification centers of the axis were, respectively, as follows: for transverse diameter y = −10.752 + 4.276 × ln(age) ± 0.335 and y = −10.578 + 4.265 × ln(age) ± 0.338, for sagittal diameter y = −4.329 + 2.010 × ln(age) ± 0.182 and y = −3.934 + 1.930 × ln(age) ± 0.182, for cross-sectional area y = −7.102 + 0.520 × age ± 0.724 and y = −7.002 + 0.521 × age ± 0.726, and for volume y = −37.021 + 14.014 × ln(age) ± 1.091 and y = −37.425 + 14.197 × ln(age) ± 1.109.

Conclusions

With no sex differences, the odontoid and body ossification centers of the axis grow logarithmically in transverse and sagittal diameters, and in volume, while proportionately in cross-sectional area. Our specific-age reference data for the odontoid and body ossification centers of the axis may be relevant for determining the fetal stage and maturity and for in utero three-dimensional sonographic detecting segmentation anomalies of the axis.