Fetal Age Estimation Using Orbital Measurements: 3D CT-Scan Study Including the Effects of Trisomy 21

Abstract:  This study evaluates a new method of fetal age estimation based on orbital measurement and including the potential trisomy 21 of the fetus. Six orbital and one facial CT-scan measurements were taken on 71 fetuses ranging from 14 to 41 weeks of gestational age. Forty-eight fetuses were "normal" and 23 fetuses presented the Down syndrome (trisomy 21). The anatomy/imagery correspondence was evaluated comparing our results to those obtained by direct bone measurements on the same fetuses and revealed no significant differences between the two kinds of measurements. Moreover, a multiple linear stepwise regression was realized to estimate fetal age and showed that the "trisomy 21 parameter" is not conserved in the final determination model. Therefore, we conclude that the good radio-anatomical correspondence offers an interesting alternative to direct bone measurement (necessitating dissections) and allows a reliable fetal age determination, whatever is the trisomy 21 condition of the fetus.     

Fetal visceral maturation: a useful contribution to gestational age estimation in human fetuses

With regard to the law, estimating fetal age is essential to assess viability (after 20 weeks according to the WHO) and the proposed methods generally use long bone measurements. Here, we evaluated the accuracy of soft tissue maturational stage and compared it with long bone measurements. First, eight kinds of tissues or organs from 448 fetuses with known medical history were studied (macroscopically or histologically). We clearly demonstrated that adrenal glands and skin were very good age indicators, because some characteristics appeared only after 20 weeks. We established a linear regression with a 95% confidence interval of +/- 2.9 weeks. Second, we applied our original formula using femur measurement and we combined soft tissues and bones in a multiparametric regression. The confidence interval was reduced to +/- 2.5 weeks. We conclude that the pathologist must use both histological and anthropometric data to determine fetal age as accurately as possible.     

Sexual Dimorphism of the Fetal Ilium: A 3D Geometric Morphometric Approach with Multislice Computed Tomography

Adult sexual dimorphism is well established. However, data regarding fetuses are sparse with contradictory results. Our study aimed to look for fetal sexual dimorphism. Multislice computed tomography (MSCT) examinations and three‐dimensional (3D) reconstructions were recorded on 93 fetal iliac bones aged between 21 and 40 weeks of amenorrhea (WA). The collection was divided into two age groups, with a cutoff at 30 WA. The 3D geometric morphometric analysis was based on outline analysis. We used elliptic Fourier analysis (EFA) because of the difficulty of landmark positioning. Step‐by‐step reconstructions allowed a better comprehension of the fine shape details. Principal component analysis (PCA) and linear discriminant analysis (LDA) were performed on the two age groups. Results did not show any difference between male and female shapes, in both age groups. We demonstrate the feasibility of outline analysis for immature shapes, but sexual dimorphism has not been established in our collection.     

Age Estimation of Infants Through Metric Analysis of Developing Anterior Deciduous Teeth

This study provides regression equations for estimation of age of infants from the dimensions of their developing deciduous teeth. The sample comprises 97 individuals of known sex and age (62 boys, 35 girls), aged between 2 days and 1,081 days. The age‐estimation equations were obtained for the sexes combined, as well as for each sex separately, thus including “sex” as an independent variable. The values of the correlations and determination coefficients obtained for each regression equation indicate good fits for most of the equations obtained. The “sex” factor was statistically significant when included as an independent variable in seven of the regression equations. However, the “sex” factor provided an advantage for age estimation in only three of the equations, compared to those that did not include “sex” as a factor. These data suggest that the ages of infants can be accurately estimated from measurements of their developing deciduous teeth.     

Validation of a radiographic method to establish new fetal growth standards: radio-anatomical correlation

In forensic medicine, specialists might face difficulties when estimating age at death from fetal remains. Depending on the state of preservation, this age assessment is essentially based on the diaphyseal size of long bones. In a previous work, for the measurement of fetal femoral ossified shafts, we already established a simple and reliable method using a radiographic protocol. Since we previously stated that radiographic measurement values were closer to real anatomical size than ultrasonographic ones, in the present study we decided to check the importance of the difference between radiographic and anatomical measurements. Therefore, we dissected 30 pairs of fetal femurs and compared the difference between the two kinds of measurements (in percentages). This difference seemed to be slight (4.027%), but it was large enough to entail significant differences (p < 0.001). In order to provide a correction factor for radiographic measurements, we established a linear regression formula, which was tested on another sample of 30 pairs of dissected femurs. As a consequence of the good results, we improved the linear regression using a powerful statistical tool: the bootstrap. Finally, we obtained a simple equation that allowed us to figure out the real anatomical size with an R2 of 99% and a mean relative difference of 0.153% (with a standard error of 0.252 mm, and therefore a 95% confidence interval with limits of -0.35 and 0.657 mm). This difference did not entail any significant differences (p = 0.498), and therefore, we concluded that with the proposed correction, radiographic measurements can easily be used by forensic specialists in their daily tasks or to establish new growth standards in order to best fit their population of interest.     

Bidimensional Data Allow for Better Age Estimation on Immature Specimens than Unidimensional Data: A Preliminary Study on the Ilium

Most biometric age estimation methods used in anthropological and forensic science for juveniles are based on unidimensional measurements (length or width). Here, a new method using bidimensional data was tested. A 3D morphometric analysis was performed on 108 CT scans of ilium bone of juveniles (from 20 gestational weeks to 12 years old). The sample was divided into training and validation groups. Best predictors were determined by comparing the efficiency of each variable (length, width, area, and module: a product of length and width). We established linear and polynomial regressions for each parameter for both sides. Applying the equations to the validation sample showed no significant difference between real and predicted ages. For age estimation, the area and module parameters yielded better results than unidimensional measurements. The results from this preliminary study were highly conclusive, and it would be interesting to extend the work, covering larger samples, and other bones.     

Estimation of fetal age from dimensions of atlas and axis ossification centers

The atlas and axis ossification centers of 106 human fetal and neonate skeletons were measured. The skeletons belong to the collection in the Department of Forensic Medicine of the Albert Szent-Gy?rgyi Medical University, Szeged, Hungary. The age of the skeletons ranged from 4 to 10 lunar months. Nine linear measurements on the atlas, seven on the axis neural arches ossification centers and three on each one of the axis centra ossification centers were taken. We did simple and multiple linear regression analysis to estimate the age of fetuses. The results show that it is possible to use regression equations to estimate the fetal body length and age from atlas and axis ossification centers measurements during the whole period of development studied. The study of size and shape of the ossification centers using factorial analysis (principal component analysis) shows that the shape of the dens of the axis might be useful to estimate fetal viability.     

青少年肩关节X线片的骨龄研究

目的探讨青少年肩关节X线影像与年龄间的关系。方法对太原地区267名年龄在12～22岁的青少年拍摄肩关节X线片,根据X线片上的不同年龄特征,筛选出5个与年龄变化密切相关的影像标志点,进行分级评分,提出了肩关节X线片判定年龄的观察指标及分级标准,并使用SPSS包进行数据处理,建立了利用肩关节X线片判定青少年年龄的判别方程。结果判别方程y=9.517+0.518x1+0.913x2+0.465x3+0.436x4经方差分析,F>0.01,回归高度显著。将全部样本进行计算机方程回代检验,符合率为±1S72.01%,±2S96.3%,其结果达到了设计与统计学要求。方程具有实用价值。结论本项研究证实了青少年肩关节X线影像与年龄之间存在相关关系,并为司法鉴定时根据肩关节X线片判断年龄提供依据,同时也为人类学研究积累了资料。     

Postmortem assessment of fetal diaphyseal femoral length: validation of a radiographic methodology

Depending on the general condition of fetal remains, forensic specialists might face difficulties concerning age estimation. Reference tables and regression equations are helpful devices in this task, although they are generally applied for complete fetuses or fetal remains including soft tissues. However, the problem of age estimation stays for osseous remains, both for entire bones and ossified parts, since most of the reference tables come from ultrasonographic measurements, which are not easily reproducible on fetal osseous remains. Furthermore, the ultrasonographic measurements contain slight errors in comparison to the real anatomical ones. This study describes a radiographic protocol and a measurement technique that facilitate and improve bone measurements, and therefore, facilitate age estimation, too. A qualitative criterion, namely a clear-cut bony endplate, was defined and tested. Its reliability (repeatability and reproducibility) turned out to be good, showing nonsignificative differences to the threshold of 0.05, with average errors of 0.26 and 0.44 mm respectively. Moreover, concerning the test of eventual size differences between the right and left femurs showed a P value < 0.0001. The test of the qualitative criterion was based on the comparison of the radiographic in situ femur measurements and the radiographic measurements of the same bones after dissection. The results were satisfactory, since an average error of 0.58 mm was obtained, which did not give any significant differences to the threshold of 0.05. It was concluded that this methodology provides an easy and precise new measurement tool for forensic practice, and can allow us to establish some nonultrasonographic tables, which fit our population.     

Determination of fetal age by immunohistochemical estimation of surfactant-producing alveolar type II cells.

We monitored the immunohistochemically determined amount of surfactant-producing alveolar type II cells in human fetal lung using polyclonal antibodies against apoprotein B and C of human pulmonary surfactant. Lungs of 30 dead-born fetuses without lung affection aged between 15 and 38 weeks of gestation were evaluated and the surface density of surfactant-producing alveolar type II cells was determined by morphometry. In lungs of fetuses with a gestational age less than 22 weeks no relevant number of positively reacting cells could be found. Between the 22nd and 29th week a progressive increase with considerable inter-individual variability was observed. From the 30th week on the number of the type II pneumocytes appeared rather constant without further significant increase. We provide evidence that the immunohistochemical detection of surfactant-producing alveolar type II cells is useful for the determination of the age of unknown and especially fragmented fetuses: The lack of surfactant-producing alveolar type II cells in fetal lungs before the 22nd week allows a rather safe distinction between fetal lungs of higher age from those of lesser age. Between the 22nd and 29th week an age-dependent increase in the number of these cells occurs with wide inter-individual variability allowing only an approximate age determination. In particular, this may be an important piece of information in fragmented fetal corpses. Furthermore, the number of surfactant-producing alveolar type II cells provides additional information on pulmonary maturation and may thus be helpful in the estimation of a theoretical survival chance.     

Probabilistic Classification of Age by Third Molar Development: The Use of Soft Evidence

Abstract: This study introduces a method to classify individuals according to an age threshold, given sex and third molars’ dental maturity measured on the Demirjian scale by expressing uncertainty on dental evidence (soft evidence). We introduced a procedure to learn the parameters of the Naïve Bayes model, and we discussed two classification rules. The model was estimated and tested on 559 Italians aged 16–22. Two experts provided the dental evaluations, and the model was estimated for each of them. We evaluated the coherence of the evidence provided by the experts. Some indexes have been proposed to evaluate the effectiveness of the models, emphasizing how the experts’ ability and the technology affect the results. We introduced two benchmarks, one based on the sample distribution per sex and age: in this case, probability of correct classification increases 22% and the proportion of false adults impressively decreases 80.2%; the other benchmark, obtained by simulating hard evidence, shows how the use of soft evidence increases the proportion of correct classification 3.1% and decreases the crucial proportion of false adults about 20%. Similarly, the proportion of false minors decreases about 5.3%.     

中国人男性硬腭的年龄变化研究

目的探讨腭缝及硬腭骨质年龄变化的规律,建立腭骨年龄判定的方法。方法对268例已知生前确切年龄的中国汉族男性的上腭硬腭腭缝的愈合情况及硬腭表面的骨质情况,进行了观察,将观察结果进行评分分级后,探讨硬腭骨骼特征与年龄的关系。结果将硬腭骨骼特征与年龄进行相关分析,并建立硬腭判定年龄的多组回归方程,判断年龄误差最小的为4.5岁。结论本文提出的硬腭年龄判定的方法,准确性较高,在较大年龄组的个体也可以得到较好的结果,是骨骼年龄判定的一个新的实用、可靠的方法。     

Age estimation in small children: reference values based on counts of deciduous teeth in Finns

The eruption of teeth in the mouth is suitable for age estimations during the period when teeth are actively emerging, in the deciduous dentition phase approximately from the age of 6 months to 2.5 years. Estimations of age can be performed simply by counting the number of teeth in the mouth. Reliability of the estimates depends on the reference data available and each population group should preferably have its own standards. In the present study timing of eruption of successive deciduous teeth was studied longitudinally in 129 Finns. The dates of clinical eruption of deciduous teeth were recorded by mothers and checked by dentists. In 40 of the 129 children emergence ages of at the most the four last teeth were based only on semiannual registrations performed by dentists. The main purpose was to provide normal timetables of tooth eruption in small children in forms that are practical in estimations of dental age. No sexual dimorphism existed in the timing of clinical eruption of successive deciduous teeth. The mean age corresponding to the presence of one tooth in the mouth was 7.1 months (S.D.=1.78) and that corresponding to tooth count 19 was 27.8 months (S.D.=3.99). If the chronological age is known, the presented distributions and means with variations make it possible to estimate the degree of advancement or delay in a child’s dental development. If the age of the child is not known, the mean and median ages can be used for estimations of chronological age. However, estimations of age should not be based only on tooth counts because of marked variation also within this homogeneous group.     

Radiographic evaluation of third molar development in relation to chronological age among Turkish children and youth

A sharp increase in forensic age estimation of living persons has been observed in recent years. However, ethnic populations residing in different countries have been insufficiently analyzed. According to 2004 data compiled by the Essen-based Turkey Research Center, there are 3.8 million Turkish people living abroad, and 3.2 million of them reside in European Union countries. Despite the high number of Turks living abroad, little is known about third-molar development for forensic application in this population. Hence, it was considered worthwhile to determine the developmental stages of the third molar in a group of Turkish population, to assess chronological age estimation based on the developmental stages, and to compare third molar development according to sex, age and location. Orthopantomograms of 1134 Turkish patients, ages 4-20 years were examined and third-molar developmental stages were evaluated based on Demirjian's classifications. Orthopantomograms were scored by two different observers, and Wilcoxon matched-pairs signed-ranks test used to test intra- and inter-observer reliability revealed a strong agreement between both intra- and inter-observer measurements. Linear regression analysis was performed to correlate third-molar development and chronological age, and further statistical analysis was performed to determine the relation between sex, age and location. Results showed a strong linear correlation between age and molar development (males: r(2)=0.57; females: r(2)=0.56). Mineralizations of left and right third molars were compared using Wilcoxon tests, and no statistical differences were found. No significant differences were found in third-molar development between males and females. Mandibular third molar crypt formation was observed in 2.4% of patients at age seven and maxillary third molar crypt formation was observed in 1.3% of patients at age seven. A strong correlation was found between third-molar development and chronological age. Among the Turkish population, third molar crypt formation is observable at as early as 7 years in both the mandible and maxilla. Agenesis can be determined conclusively if no radiolucent bud is present by age 14.     

Fetal gunshot wound characteristics

Firearm injury in pregnant women is reported in the literature; however, no articles to date address the forensic analysis of the wounds sustained by the fetus. This is a report of a 40 weeks gestational age fetus who died following multiple perforating gunshot wounds, while his mother survived. The fetal wounds were atypical, consisting of irregular perforations with radiating linear lacerations and adjacent abrasions. The unusual wound pattern may have been due to the presence of interposed targets, the shoring of the fetus against itself and the uterine corpus, and the intrinsic character of fetal skin.     

On the applicability of secondary dentin formation to radiological age estimation in young adults

The literature provides linear regression formulas for dental age estimation that is based on radiological two-dimensional measurements of the pulp size. The aim of the present study was to explore whether the previously presented regression formulas could lead to statistically sound results and to appropriate repeatability when applied to young individuals. Orthopantomograms (OPGs) of 44 Austrian individuals, aged between 13 and 24 years, were selected at random. In accordance with the reported method, six teeth on each OPG were chosen to carry out the measurements. Statistical analysis was performed in order to assess the difference between the estimated and the true chronological age. The regression formulas reported by Kvaal et al. (1995) led to a consistent underestimation; the regression formulas reported by Paewinsky et al. (2005) resulted in a constant overestimation of age. The statistical analysis of intraobserver and interobserver variation revealed a variation width below 2%, respectively.     

TW2、TW3法腕骨骨龄评价方法的诊断性试验

目的比较TW2法英国人标准、TW2法中国人南方标准和TW3法测定腕骨骨龄对特发性性早熟(IPP)女孩的诊断价值。方法女性IPP患儿55例;对照组83例。回顾性分析初诊左腕X线片,用TW2法、TW2CHC中国人南方标准和TW3法盲法分期,分别测得其腕骨骨龄及其百分位,并分为5个连续性的工作点,即:>P97、>P90、>P75、>P50和、≤P50。结果敏感度(Sen)和特异度(Spe)都比较高的有以下3个工作点:TW2CH“>P90”点,TW3“>P90”点,TW2“>P90”点。结论TW系统3种腕骨骨龄对于IPP女孩都有诊断价值,TW3法和TW2法中国人南方标准诊断价值比较高,TW2法英国人标准的诊断价值为中等。     

Radiographic determination of developmental age in fetuses and stillborns.

The gestational age and/or viability of a fetus can become an important forensic issue. Several investigators have produced linear regression formulas based on crown-heel length (CHL), crown-rump length, or body diameters to determine gestational age. This study re-examines the relationship between fetal long bone length and CHL and tests a method of estimating CHL, and therefore gestational age, from radiographic measurements of the major long bone diaphyses. The results are compared with data based on dry bone measurements. Data from 252 cases confirm a strong correlation between all long bone lengths and CHL (> or = r = .9063; p < 0.01). Long bone length means for each CHL group are presented, as well as regression formulas for estimating CHL from radiographic measurements of the long bone diaphyses. The findings correspond closely with results based on a European sample, thereby validating that reference population as a normative sample for fetal analysis in the United States. The radiographic method can be used in instances where skeletal preparation is impossible or undesirable.