Fetal age estimation using MSCT scans of the mandible

Fetal facial bone growth: Post-mortem CT analysis

OBJECTIVE

To describe and model the normal growth of fetal facial bones and angles.

MATERIAL AND METHODS

A total of 118 fetal CT scans obtained at 19 to 41 weeks gestation after in utero fetal death or late miscarriage were analyzed. CT scan was followed by autopsy and pathological examination and only fetuses free from brain disease or abnormal craniofacial development were included. The measurements were taken using software for frontal, sagittal and 3D reconstruction from native axial sections. The optimal plane for bone analysis was chosen and the measurements made by multiplanar reconstruction.

RESULTS

There was a statistically significant increase (P<0.001) in all measurements regardless of gestational age (GA) except those of the mandibulo-fronto-maxillary angle (P=0.412), the naso-mandibulo-maxillary angle (P=0.828) and mandibular width (P=0.86). There was no significant difference according to fetal sex. Based on these results, the corresponding growth curves were created. The anteroposterior mandibular diameter (APD) was very strongly correlated with GA (R=0.926, P<0.001). The following equation: GA=(8.187×APD)+4.257 can be used to estimate GA with a confidence interval (CI) of±2.42. The same applies to maxillary width (MW) (R=0.922; P<0.001). The equation GA=(11.059×MW)+7.571 can be used to estimate GA with a CI of 2.17.

CONCLUSION

The growth of the mandible, maxilla, zygomatic bone and orbits was measured and the corresponding growth curves were established. Several measurements were strongly correlated with gestational age.

PECULIARITIES OF THE SOURCES OF ORIGIN AND MORPHOGENESIS OF THE HUMAN MANDIBLE

OBJECTIVE

The aim: To determine the sources and terms of origin, developmental peculiarities and dynamics of ossification of the mandible during the prenatal period of human ontogenesis.

PATIENTS AND METHODS

Materials and methods: The research was carried out on the specimens of 30 embryos, 30 pre-fetuses and 60 human fetuses at the period from the 9th to the 12th weeks of the intrauterine development, which were studied by microscopic examination. Three-dimensional computer reconstructions of the human pre-fetal head were made.

RESULTS

Results: During the 7th week of development the maxillary processes maximum approach the lateral and medial nasal ones; in pre-fetuses 20,0 mm of PCL they join the frontal spindle forming the facial structures (upper jaw and lip, vestibule of the oral cavity, rudiments of dental laminas, and rudiments of dental buds in its distal portions). Osteogenous islets, rudiments of the mimic and masticatory muscles, blood vessels are formed. During the 8th week of development the osseous tissue of the mandible is formed, the alveolar processes are formed. The oral and nasal cavities are isolated in 9-10-week pre-fetuses, the mass of the osseous tissue increases in both jaws, the enamel organs are detached, the angles and rami formed by the hyaline cartilaginous tissue of the mandible are determined, the rudiments of the temporomandibular joints are already seen. During the 11th week of development the osseous base of both jaws become formed. Till the end of the 12th week the osseous tissue begins to replace the hyaline cartilage of the mandibular rami, and the articular heads are formed in the portion of their proximal ends.

CONCLUSION

Conclusions: The mandible in its development is known to be characterized by intra-cartilaginous formation of the bone which starts from the ends of the cartilage gradually displaced by the osseous tissue. It is indicated that both jaws in pre-fetuses 37,0 and 42,0 mm of PCL are presented by the typical cartilaginous tissue, and in pre-fetuses 45,0-50,0 mm of PCL the osseous tissue is already available replacing the cartilaginous one.

Age estimation of immature human skeletal remains from mandibular and cranial bone dimensions in the postnatal period

Age estimation is one of the crucial first steps in the identification of human skeletal remains in both forensic and archeological contexts. In the postnatal period, age is traditionally estimated from dental development or skeletal growth, typically long bone diaphyseal length. However, in many occasions other methods are required. This study provides alternative means of estimating age of juvenile remains from the size of several cranial bones and the mandible. A sample of 185 identified juvenile skeletons between birth and 13 years of age from two European collections were used (Lisbon and Spitalfields). Measurements of the frontal, occipital-lateralis, occipital-basilaris, occipital-squamous, zygomatic, maxilla, and mandible were used to calculate classical calibration regression formulae for the sexes combined. The sample was divided into three age groups birth-2 years, 2-6 years, and 2-12.9 years, depending on bone and its growth trajectory. For all the bones, measurements of the youngest age groups yielded the most precise age estimates. The vault bones on average yielded the best performing models, with the frontal bone having the most precise of all. The mandible performed on par with the best performing cranial bones, particularly in individuals under the age of 2 years. This study provides one of the most comprehensive approaches to juvenile age estimation based on bones of the skull, providing a resource that potentially can help estimate age of juvenile skeletons from a variety of circumstances.

CT Scan Imaging of the Human Fetal Labyrinth: Case Series Data Throughout Gestation

OBJECTIVES

The inner ear in humans reaches its final configuration and its adult size during fetal life. According to the literature, this occurs between 18 and 25 weeks of amenorrhea (WA). Our goal is to clarify the course of inner ear size development.

METHODS

Using computed tomography (CT) scanner, we studied 13 measurements in the inner ear of a collection of 153 fetuses from 21 to 40 WA.

RESULTS

We found no side-related differences or sexual dimorphism in the measurements. Cochlear and vestibular bone measurements did not show growth from 21 to 40 WA, with the exception of the lateral semicircular canal (LSCC) bony island, which grows until 25 WA. Internal auditory canal (IAC) and cochlear aqueduct (CA) growth are correlated with gestational age. As our cochlear measurements are similar to those of infants and adults, in accordance with the literature we conclude that the cochlea has reached its adult size before 21 WA. The continuous growth of the IAC and CA is linked to petrous ossification that continues during fetal gestation and after birth.

CONCLUSION

We confirm that the cochlea reaches its adult size during the second trimester of fetal life.