Validity of dental findings for identification by postmortem computed tomography.

Postmortem computed tomography (PMCT) images help identify individuals and extract information from corpses. PMCT may substitute for a standard examination when bodies are severely damaged or when resources are limited in a mass fatality incident. In such situations, the dental information revealed by PMCT has the potential to narrow down candidates for identification further. However, the validity of the dental findings obtained from PMCT images remains unclear. In this study, we investigated the validity of dental findings on PMCT images compared to regular dental examinations as the reference standard. We routinely collected PMCT images of 148 unidentified corpses and compared the dental findings of each tooth obtained from PMCT with those of a regular dental examination. The validity of dental findings of PMCT was measured by sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We also evaluated the accuracy of dental findings per corpse using 32 teeth as the denominator. The dental findings with high sensitivity and high specificity were a present tooth (0.96 and 0.97), a missing tooth (0.97 and 0.97), pontic (0.92 and 1.00), a dental implant (1.00 and 1.00), and a root filling (0.94 and 0.99). The mean accuracy of the dental findings per corpse in PMCT was 95.6% (standard deviation: 6.9, minimum ≤ median ≤ maximum: 65.6 ≤ 100 ≤ 100). The number of corpses with 100% accuracy in the dental findings was 81 (54.7%). The information obtained in this study highlights the potential use of PMCT during human identification in several settings with limited resources, such as the number of specialists present and the condition of the corpses.

Age estimation by evaluation of osteophytes in thoracic and lumbar vertebrae using postmortem CT images in a modern Japanese population.

Estimation of age at death is important in forensic investigations of unknown remains. There have been several reports on applying the degree of osteophyte formation-an age-related change in the vertebral body-for age estimation; however, this method is not yet established. This study investigated a method for age estimation of modern Japanese individuals using osteophytes measured on CT images. The sample included 250 cadavers (125 males) aged 20-95 years. The degree of osteophyte formation was evaluated as score O (0-5 points), and the degree of fusion of the osteophytes between the upper and lower vertebrae was evaluated as score B (0-2 points). Age estimation equations were developed using regression analyses with seven variables, determined by scores O and B, and the equation with the smallest standard error of estimate (SEE) was obtained when the number of vertebrae with score O ≥ 2 was used as the explanatory variable. Age estimation with SEE of about 10 years was possible even when partial vertebrae with a high degree of osteophyte formation were used, showing its potential for practical application. The cutoff value for age estimation was established using the receiver operating characteristic curve analysis, wherein good results were obtained for all variables (area under the curve ≥ 0.8). The combination of the estimation equation and the cutoff value can narrow the range of age estimates.

Preparation of dentin standard samples for age estimation based on increased aspartic acid racemization rate by heating.

Age estimation in adults based on aspartic acid racemization (AAR) provides fewer errors and higher precision than that based on bone morphology for the identification of cadavers. The technique has been established in some labs as a routine method. However, as the essential requisites for the technique, a wide age range of teeth of the same type as the target tooth must be collected for calibration for each examination. We investigated whether dentin standard samples could be prepared by increasing the AAR rate via heat. Powdered dentin was prepared from a maxillary first premolar (13 years) and heated for 0-72 h at 110 °C. The extent of AAR increased significantly with heating time and the correlation was strong (r = 0.913; p < 0.01). Similar results were found for a mandibular canine (24 years, r = 0.948; p < 0.01) and a maxillary third molar (20 years, r = 0.944; p < 0.01). We attempted to estimate the age of four maxillary first premolars of persons aged 25-58 years by using the heated samples (18 years, 12 h to 7 days). The differences between the actual and estimated ages were within ±5 years. The stability of the AAR rates in the powdered dentin during storage at 22-25 °C, 4 °C, and -30 °C was examined after 1 year and no significant changes had occurred. We were able to prepare dentin standard samples and created a calibration curve. This is a pilot study that needs to be validated before it can be used in forensic practice.

Estimation of birth year by radiocarbon dating of tooth enamel: Approach to obtaining enamel powder.

Atmospheric radiocarbon (14C) levels increased from 1955 to 1963 due to atmospheric nuclear weapon tests, and then decreased. As 14C accumulates in human tooth enamel while the enamel is being formed, 14C can be used to estimate the birth year of unidentified bodies. Measurement results of 14C content in tooth enamel using accelerator mass spectrometry vary depending on the enamel's sample site. To address this problem, a method for equalizing samples using a pulverizer was considered in this study. Regarding the tube and cone used as the pulverizer, (1) a polycarbonate tube and stainless steel cone, (2) a stainless steel tube and cone, and (3) a tungsten carbide tube and cone, were compared. In (1), the modern carbon ratio was approximately half that of the normal ratio of 100 pMC, with which accurate dating was impossible, and in (2), a high background value was obtained for IAEA-C1, which was pulverized using a reusable tube and cone. In (3), the 14C content for IAEA-C1 pulverized using reusable tube and cone, which was washed with quartz sand, was 0.31 ±â€¯0.01 pMC. This result did not show any problems regarding background value. Therefore, the use of tungsten carbide products and washing with quartz sand is recommended for 14C measurement of pulverized teeth.

Sex estimation based on femoral measurements using multidetector computed tomography in cadavers in modern Japan.

We aimed to reproduce the anthropometrical measurements of femoral dimensions using multi-planar reconstruction (MPR) computed tomography (CT); to assess the feasibility of sex estimation using femoral measurements through this approach, and to establish the corresponding sex estimation thresholds in the modern Japanese population. We used data on 224 cadavers (116 male and 108 female) that were subjected to postmortem CT and subsequent forensic autopsy at our department between October 2009 and July 2016. Four femoral measurements were obtained. Receiver operating characteristic (ROC) curve analysis was performed to test the overall ability of the variables in sex estimation, while the accuracy of the sex estimation was measured by the area under the ROC curve (AUC). The femoral bicondylar breadth showed the largest AUC values (left; 0.973, right; 0.974), followed by the maximum head diameter (left; 0.951, right; 0.955), and maximum femoral length (left; 0.885, right; 0.887). To the best of our knowledge, this is the first report to assess sex estimation based on femoral measurements, using MPR CT images.

Stature estimation based on femoral measurements in the modern Japanese population: a cadaveric study using multidetector computed tomography.

We aimed to reproduce the anthropometrical measurement of femoral dimensions using multi-planar reconstruction computed tomography (CT), assess the correlation between stature and femoral measurements obtained by this approach, and establish a regression equation for estimating stature in the modern Japanese population. We used data regarding 224 cadavers (116 males, 108 females) that were subjected to postmortem CT and subsequent forensic autopsy at our department between October 2009 and July 2016. To simulate the placement of the femur on the osteometric board using reconstructed CT images, we defined a virtual horizontal plane (VHP) based on the three most dorsal points of the femur (lateral condyle, medial condyle, and greater trochanter). Five femoral measurements including the maximum femoral length (MFL) were obtained. The correlations between stature and each femoral measurement were expressed in terms of the coefficient of determination (R2). On regression analysis, MFL provided the lowest value for the standard error of the estimation (SEE); the SEE values in all subjects, males, and females, respectively, were 3.783 cm (R2 = 0.832), 3.850 cm (R2 = 0.653), and 3.340 cm (R2 = 0.760) for MFL on the left side and 3.747 cm (R2 = 0.835), 3.847 cm (R2 = 0.650), and 3.290 cm (R2 = 0.687) for MFL on the right side. Multiple regression equations using MFL and femoral epicondylar breadth were slightly superior to simple regression equations in males and in all subjects (SEE = 3.44-3.55 cm), whereas no effective equation could be obtained in females. To our knowledge, this is the first multiple regression equation for stature estimation using only femoral measurements.

Sex assessment based on clavicular measurements in a modern Japanese population using multidetector computed tomography.

Accurate sex estimation from unknown human remains is crucial as an integral and foremost step toward individual identification. The aims of this study were to assess sexual dimorphism of the clavicle and develop discriminant equations for sex estimation in a modern adult Japanese population based on clavicular measurements using three-dimensional (3D) computed tomographic (CT) images. A total of 300 cadavers (150 males, 150 females) of known age and sex that underwent postmortem CT and subsequent forensic autopsy were obtained. Four measurements were performed using 3D CT reconstructed images that extracted only bones based on the CT values, as follows: the linear distances between the medial superior margins of the left and right sternal facets to the lateral points of the left and right acromial ends, and the linear distances between the medial superior margins of the left and right sternal facets to the tips of the left and right conoid tubercles. The mean values of all measurements were significantly greater for male subjects than female subjects. Univariate discriminant function analysis (DFA) provided correct sex prediction rates of 88.3-92.2%. Stepwise DFA for the left and right clavicles yielded sex classification accuracy rates of 92.2% and 91.0%, respectively. In conclusion, clavicular measurements using 3D CT images of a contemporary Japanese population may be useful for sex estimation in forensic contexts.

Postmortem angiography revealing traumatic rupture of the intracranial internal carotid artery.

Diagnosis of traumatic subarachnoid hemorrhage (SAH), although relatively rare, is important in forensic medicine. It is mostly associated with rupture of the vertebrobasilar artery. Traumatic aneurysm of the intracranial part of the internal carotid artery (ICA) is also rare but has been reported in several studies. It is thought that the intracranial ICA is injured by blunt force to the head, neck, and chest. However, traumatic SAH with fatal acute course resulting from rupture of the ICA is especially uncommon: only two fatal cases without an associated aneurysm have been reported in the English-language literature. Although detecting the arterial lesion is required to make a precise diagnosis, this is sometimes impossible by macroscopic examination at autopsy or by investigation after formalin-fixation according to the position of the lesion. We report a rare case of fatal traumatic SAH associated with intracranial ICA rupture. Postmortem computed tomography angiography was useful to confirm the lesion.

Stature estimation in a contemporary Japanese population based on clavicular measurements using multidetector computed tomography.

The aims of this study was to assess the correlation between stature and clavicular measurements in a contemporary Japanese population using three-dimensional (3D) computed tomographic (CT) images, and to establish regression equations for predicting stature. A total of 249 cadavers (131 males, 118 females) underwent postmortem CT scanning and subsequent forensic autopsy between October 2011 and May 2016 in our department. Four clavicular variables (linear distances between the superior margins of the left and right sternal facets to the anterior points of the left and right acromial ends and between the superior margins of the left and right sternal facets to the left and right conoid tubercles) were measured using 3D CT reconstructed images that extracted only bone data. The correlations between stature and each of the clavicular measurements were assessed with Pearson product-moment correlation coefficients. These clavicular measurements correlated significantly with stature in both sexes. The lowest standard error of estimation value in all, male, and female subjects was 3.62cm (r2=0.836), 3.55cm (r2=0.566), and 3.43cm (r2=0.663), respectively. In conclusion, clavicular measurements obtained from 3D CT images may be useful for stature estimation of Japanese individuals, particularly in cases where better predictors, such as long bones, are not available.

Incidence of three-rooted mandibular first molars among contemporary Japanese individuals determined using multidetector computed tomography.

PURPOSE: The purpose of this study was to determine the incidence of three-rooted mandibular first molars in a contemporary Japanese population using multidetector computed tomography (MDCT) and examine whether this characteristic root form may be useful for identification purposes. METHODS: Prior to their forensic autopsies, we obtained MDCT scans of 365 cadavers (255 males, 110 females) with mandibular first molars on both sides. Altogether, 730 mandibular first molars were examined morphologically on reconstructed CT images, and the incidence of three-rooted molars was recorded. The results were analyzed statistically to determine sex and left-right differences using the chi-square test. RESULTS: In all, 189 (25.9%) of the 730 mandibular first molars had three roots: 79 (31.0%) in the 255 males and 35 (31.8%) in the 110 females. No statistically significant difference was found between the sexes. In the 39 individuals who had unilateral three-rooted mandibular first molars, 7 (17.9%) were on the left side and 32 (82.1%) were on the right side, indicating a statistically significant predominance on the right side. CONCLUSIONS: The incidence of three-rooted mandibular first molars in contemporary Japanese individuals was 25.9%, with no statistically significant sex difference, but in the case of unilateral three-rooted teeth, with a statistically significant predominance on the right side. Our study found that Japanese and northeastern Asians have a high incidence of the three-rooted mandibular first molars among individuals of Mongolian origin; this finding may be a useful screening tool for identification of unknown individuals.

A rare autopsy case of traumatic rhabdomyolysis associated with intermittent assault.

Traumatic rhabdomyolysis generally occurs after severe blunt trauma and is acute in onset, associated with severe disease, and potentially lethal. Accordingly, diagnosis of traumatic rhabdomyolysis in patients without massive subcutaneous or intramuscular hemorrhage is difficult, especially in the postmortem period, which is limited in terms of the availability of biochemical examination tools and accurate history of illness. To the best of our knowledge, there are no previous reports of death from traumatic rhabdomyolysis among individuals who did not pursue medical consultation. A previously healthy man in his early sixties had been punched and kicked several times in the previous 2months, but he had not gone to a hospital. He suddenly lost consciousness at his workplace approximately 5days after the most recent assault, and cardiopulmonary arrest occurred when the emergency service arrived. He died the same day, and a medicolegal autopsy was performed. Although several sites of minor subcutaneous and muscle hemorrhage were observed, the cause of death was unclear upon macroscopic assessment. Immunohistochemical staining revealed acute renal failure caused by rhabdomyolysis. We herein report a rare case of fatal traumatic rhabdomyolysis, seemingly associated with minor and apparently nonlethal muscle injury.

Sexual determination based on multidetector computed tomographic measurements of the second cervical vertebra in a contemporary Japanese population.

Accurate sex estimation is important in forensic investigation to determine the identity of unknown individuals. The aim of this study was to investigate the accuracy of sex assessment based on measurements of the second cervical vertebra (C2) using computed tomographic (CT) images in a Japanese population and to develop discriminant function formulae. The data were collected from 224 Japanese cadavers (112 male subjects, 112 female subjects) on which postmortem CT scanning and subsequent forensic autopsy were performed. Nine CT measurements of the C2 were performed for CT images of each subject. The measurements were assessed using descriptive statistics and discriminant function analyses (DFA). All of the measurements demonstrated significant sexual dimorphism. Multiple DFA with stepwise variable selection resulted in multivariable models; a five-variable model reached an accuracy rate of 92.9%. Our results suggest that metric analysis based on CT images of the C2 can accurately determine the sex from the human skeletal remains in a contemporary Japanese population and may be useful for sex estimation in forensic anthropology.

Sex estimation based on scapula analysis in a Japanese population using multidetector computed tomography.

Accurate sex estimation based on measurements of dimorphic dimensions in human unknown remains is important as the first step toward making individual identification. The purpose of this study was to assess the sexual dimorphism of the scapula and to quantify the accuracy of sex estimation in a contemporary Japanese forensic sample using scapular measurements based on three-dimensional (3D) computed tomographic (CT) images. A total of 218 cadavers (109 males, 109 females) that underwent postmortem CT and subsequent forensic autopsy were used. Ten scapular measurements were performed on 3D CT reconstructed images that extracted only bone data, and were analyzed using descriptive statistics and discriminant function analyses (DFA). All measurements were dimorphic in terms of sex differences. Univariate DFA provided sex classification accuracy rates of 75.7-91.3%. Stepwise DFA yielded sex prediction accuracy rates of 93.1-94.5%. In conclusion, the scapular measurements using 3D CT images of a contemporary Japanese population may be useful for the estimation of skeletal sex in the field of forensic anthropology.

Stature estimation from skull measurements using multidetector computed tomographic images: A Japanese forensic sample.

The aim of this study was to assess the correlation between stature and cranial measurements in a contemporary Japanese population, using three-dimensional (3D) computed tomographic (CT) images. A total of 228 cadavers (123 males, 105 females) underwent postmortem CT scanning and subsequent forensic autopsy between May 2011 and April 2015. Five cranial measurements were taken from 3D CT reconstructed images that extracted only cranial data. The correlations between stature and each of the cranial measurements were assessed with Pearson product-moment correlation coefficients. Simple and multiple regression analyses showed significant correlations between stature and cranial measurements. In conclusion, cranial measurements obtained from 3D CT images may be useful for forensic estimation of the stature of Japanese individuals, particularly in cases where better predictors, such as long bones, are not available.

Morphometric analysis of sex differences in contemporary Japanese pelves using multidetector computed tomography.

Sex estimation of decomposed or skeletal remains is clearly important in forensic contexts. Recently, contemporary population-specific data has been obtained using multidetector computed tomography (MDCT) scanning. The main purpose of this study was to investigate skeletal pelvic dimorphism in a contemporary Japanese forensic sample and to quantify the accuracy of sex estimation using various pelvic measurements obtained from three-dimensional (3D) CT images. This study used a total of 208 cadavers (104 males, 104 females) of which postmortem CT scanning and subsequent forensic autopsy were conducted between December 2011 and August 2014. Eleven measurements of each pelvis were obtained from 3D CT reconstructed images that extracted only bone data. The measurements were analyzed using descriptive statistics and discriminant function analyses. All except one measurement were dimorphic in terms of sex differences. Univariate discriminant function analyses using these measurements provided sex classification accuracy rates of 62.0-98.1%. The subpubic angle was found to contribute most significantly to accurate sex estimation. Multivariate discriminant functions yielded sex prediction accuracy rates of 63.9-98.1%. In conclusion, the pelvic measurements obtained from 3D CT images of a contemporary Japanese population successfully demonstrated sexual dimorphism and may be useful for the estimation of skeletal sex in the field of forensic anthropology.

The effects of racemization rate for age estimation of pink teeth.

Pink teeth is thought to result from the seepage of hemoglobin caused by dental pulp decomposition. We investigated whether racemization can be applied for age estimation in cases of pink teeth where the whole tooth is used. The pink teeth used were three cases and the normal teeth for control were five mandibular canines of known age. Age of the pink teeth was calculated on the basis of regression formula obtained from the five control teeth. Only a slight error was noted between the actual and estimated ages of the pink teeth (R(2) = 0.980, r = 0.990): Cases 1-3 actually aged 23, 53, and 59 years were estimated to be 26, 52, and 60 years. Based on our results of testing pink teeth of known age, we suggest that racemization techniques allow for the age estimation of pink teeth using the same methods for normally colored teeth.

Estimation of sex in Japanese cadavers based on sternal measurements using multidetector computed tomography.

This study assessed the sex-discrimination potential of the sternum in a Japanese population using three-dimensional (3D) computed tomographic (CT) images. A total of 200 cadavers (100 males, 100 females) who underwent postmortem CT and subsequent forensic autopsy between December 2011 and June 2014 were used. Five measurements of each sternum were performed on 3D CT reconstructed images that extracted only bone data, and two sternal dimensions and three indices were calculated. Univariate discriminant function analyses using these linear measurements and calculated sternal dimensions and indices yielded sex classification accuracy rates of 62.5-84.0%, and 63.0-90.5%, respectively. The results of this study indicate that sternal measurements may be useful for the forensic assessment of sex in Japanese individuals, particularly in cases where better predictors, such as the pelvis or skull, are unavailable.

Stature estimation in Japanese cadavers based on scapular measurements using multidetector computed tomography.

This study assessed the correlation between stature and scapular measurements in a Japanese population, using three-dimensional (3D) computed tomographic (CT) images, and derived regression equations for predicting stature. A total of 194 cadavers (100 males 94 females) underwent postmortem CT (PMCT) and subsequent forensic autopsy in our department between May 2011 and April 2014. Left and right longitudinal scapular lengths (LLSL and RLSL, respectively) and left and right transverse scapular lengths (LTSL and RTSL, respectively) were measured on 3D CT reconstructed images that extracted only scapular data. The correlation between stature and each of the scapular measurements were analyzed using Pearson product-moment correlation coefficients. The four variables correlated significantly with stature, regardless of sex. The LLSL measurement had the lowest standard error of estimation value among all subjects (4.22 cm) and among all females (4.37 cm), whereas the RLSL measurement had the lowest standard error of estimation value among all males (3.75 cm). The results of this study indicate that scapular measurements may be useful for the forensic estimation of the stature of Japanese individuals, particularly in cases where better predictors, such as long bone lengths, are unavailable.

Stature estimation in Japanese cadavers based on the second cervical vertebra measured using multidetector computed tomography.

The purpose of this study was to assess correlations between measurements of the second cervical vertebra (C2) and stature using multidetector computed tomography (MDCT) images, and to develop regression equations for estimating stature in a Japanese population. Measurements were performed on 216 Japanese subjects (116 males and 100 females) who underwent postmortem CT between May 2011 and November 2013. Sagittal images through the center of the C2 were used for assessment. The length from the top of the dens to the anteroinferior point of the vertebral body (DA), the length from the anteroinferior point of the vertebral body to the posterior point of the spinous process (AS), and the length from the top of the dens to the posterior point of the spinous process (DS) were measured. The correlation between stature and each parameter (DA, AS, and DS) was assessed using Pearson product-moment correlation coefficients and regression analysis was performed for stature estimation. All measurements of the C2 were positively correlated with stature regardless of sex. The highest correlation was observed for the DA in all cases, and the lowest correlation was observed for AS in all cases. However, the standard errors of estimate were large. Thus, our study concludes that the size of the C2 as measured with MDCT images may be useful for stature estimation only when better predictors, such as long bones, are unavailable.

Stature estimation in Japanese cadavers based on pelvic measurements in three-dimensional multidetector computed tomographic images.

The aim of this study was to examine the feasibility of stature estimation by measuring the pelvic bones of Japanese cadavers using three-dimensional (3D) computed tomography (CT). We assessed 3D reconstructed images of 210 Japanese subjects (108 males, 102 females) who had undergone postmortem CT between May 2011 and November 2013. We defined the linear distance from the anterosuperior margin of the left and right anterior superior iliac spines (ASIS) to the posterior margin of the left and right ischial spines as the LSS and RSS, respectively. We also defined the linear distance from the anterosuperior margin of the left and right ASIS to the anteroinferior margin of the left and right ischial tuberosities as the LST and RST, respectively. The correlation between the cadaver stature (CS) and each parameter (LSS, LST, RSS, and RST) was evaluated using Pearson product-moment correlation coefficients and regression analysis was performed for stature estimation. All four parameters correlated significantly with stature independent of sex, suggesting that they can be used as a tool for stature estimation. The LST had the closest correlation with stature in both sexes.