Ayaka Sakuma

Application of postmortem 3D-CT facial reconstruction for personal identification.

Abstract:  Postmortem computed tomography (CT) images can show internal findings related to the cause of death, and it can be a useful method for forensic diagnosis. In this study, we scanned a ready‐made box by helical CT on 2‐mm slices in a mobile CT scanner and measured each side of the box to assess whether reconstructed images are useful for superimposition. The mean difference between the actual measurements and the measurements on the three‐dimensional (3D) reconstructed images (3D‐CT images) is 0.9 mm; we regarded it as having no effect on reconstruction for the superimposition method. Furthermore, we could get 3D‐CT images of the skull, which were consistent with the actual skull, indicating that CT images can be applied to superimposition for identification. This study suggested that postmortem CT images can be applied as superimpositions for unidentified cases, and thinner slices or cone beam CT can be a more precise tool.

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.

Evaluation of Computed Tomography as a Screening Test for Death Inquest

Abstract:  The Japanese method of inquest, which depends mostly on external examinations, may misdiagnose a considerable number of accidental deaths and suicides as death by disease. We conducted computed tomography (CT) scans of 80 cases for which police concluded death by disease or natural causes based on police investigations into the circumstances and results from external examinations. The cause of death was clearly determined by CT scan in 17 of 80 cases. Ten cases underwent autopsy after the police suspected criminality based on results of the CT examinations. The results suggest CT scan may be a tool for preventing a number of overlooked crimes and accidents in Japan. However, it cannot be a perfect tool for discerning between death by disease and other causes of death without cooperation from the investigative agencies and subsequent forensic examinations such as autopsy and toxicological tests.

Age estimation by multidetector CT images of the sagittal suture

Closure of cranial sutures progresses with age; therefore, macroscopic assessment of cranial sutures has been used as one method of age estimation. Postmortem computed tomography (PMCT), which many forensic medical departments and institutes have begun to adopt, has the potential to simplify the gathering of information from cranial sutures for both surface and cross-sectional evaluation. To examine the feasibility of age estimation by cross-sectional multidetector computed tomography images of the sagittal suture, PMCT findings of 125 subjects of known age and sex were retrospectively reviewed. The sagittal suture was divided into four segments, and 20 cross-sectional slices from each segment were analyzed. These slices were each categorized by visual evaluation into one of the seven stages defined by Harth et al. according to the degree of closure. The mean stage value of 20 slices was calculated for each segment. We were able to evaluate cross-sectional images of the sagittal suture by PMCT, and a positive correlation between age and closure degree was observed. Despite the prediction interval achieved with this method not being superior to traditional macroscopic or flat-panel CT assessment, multidetector CT is a potentially useful tool, in conjunction with other methods, for age estimation, particularly in adult females and in cases where only a skull is the sole remain.

Stature estimation based on radial and ulnar lengths using three-dimensional images from multidetector computed tomography in a Japanese population

The aim of our study was to evaluate correlations between cadaver stature (CS) and radial and ulnar lengths based on three-dimensional (3D) computed tomography (CT) images, and to develop modern regression equations for estimating CS in a Japanese population. Measurements were performed on 245 Japanese subjects (123 males and 122 females) who underwent postmortem CT between May 2011 and December 2013. A 3D reconstructed image was used for assessment. The linear distances of the left radial (LR) and right radial (RR) lengths were measured as a straight-line distance from the most anteroproximal point of the head to the most distal end of the styloid process. The linear distances of the left ulnar (LU) and right ulnar (RU) lengths were measured as a straight-line distance from the most posteroproximal point of the olecranon to the most distal end of the styloid process. The correlation between CS and each parameter (LR, LU, RR, and RU) was assessed using Pearson product-moment correlation coefficients and regression analysis was performed for stature estimation. There were significant correlations between CS and each parameter regardless of sex, indicating that the radial and ulnar lengths measured on 3D CT images can be predictive of stature estimation. Simple regression equations for stature estimation calculated from LR provided the lowest standard error of estimation (SEE) (all subjects, SEE=4.18 cm; males, SEE=4.09 cm; females, SEE=4.21 cm). In addition, multiple regression equations were more accurate and reliable than the single linear regression equations.

Age Estimation Based on Pulp Cavity to Tooth Volume Ratio Using Postmortem Computed Tomography Images

Pulp cavity size is known to decrease with age and can therefore serve as an indicator for age estimation. Here, we evaluated whether reconstructed images of multidetector‐row computed tomography (MDCT) acquired before forensic autopsy are useful for estimating age at death. Images of 136 mandibular first premolars obtained from bodies of known age at death were analyzed, and the volume of the regions corresponding to pulp cavity and that of the whole tooth were determined using a voxel counting function. The pulp cavity was clearly distinguishable from dental hard tissue on the reconstructed images when using a cutoff value of 1400 Hounsfield units. Regression analysis adjusted for sex showed that estimated age correlated significantly with the pulp cavity to tooth volume ratio (r = 0.76). MDCT is gaining more widespread use in forensic medicine, and analyzing dental images to obtain parameters for age prediction is a practical approach for postmortem identification.

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.

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.

Application of Superimposition‐Based Personal Identification Using Skull Computed Tomography Images

Abstract:  Superimposition has been applied to skulls of unidentified skeletonized corpses as a personal identification method. The current method involves layering of a skull and a facial image of a suspected person and thus requires a real skeletonized skull. In this study, we scanned skulls of skeletonized corpses by computed tomography (CT), reconstructed three‐dimensional (3D) images of skulls from the CT images, and superimposed the 3D images with facial images of the corresponding persons taken in their lives. Superimposition using 3D‐reconstructed skull images demonstrated, as did superimposition using real skulls, an adequate degree of morphological consistency between the 3D‐reconstructed skulls and persons in the facial images. Three‐dimensional skull images reconstructed from CT images can be saved as data files and the use of these images in superimposition is effective for personal identification of unidentified bodies.

Age estimation by quantitative features of pubic symphysis using multidetector computed tomography

Macroscopic assessment of the pubic symphysis is commonly used for age estimation because its surface changes over time. However, postmortem computed tomography (PMCT), a method several forensic medical departments and institutes have begun to adopt, has the potential to simplify the information gathering process from the pelvic bone without requiring soft tissue removal. Some studies have previously evaluated the use of three-dimensional images of the pubic symphysis, but because of variance in the graphics processing among image analysis software packages, certain differences have been observed between these studies. Therefore, in this study, the PMCT findings of 199 subjects of known age and sex were retrospectively reviewed to examine the feasibility of age estimation using planar images of the pubic bones and soft tissue. The coronal and axial sectional images were observed at the center of the symphyseal surface, and the pubic bone length and thickness of the connective tissue of the pubic symphysis were measured at each slice. Our results revealed a significant positive correlation between the length of the pubic bone of the coronal section and age, suggesting that the use of a cutoff value for pubic bone length might be feasible for age estimations. In addition, the thickness of the connective tissue tended to narrow over time. Although the prediction interval range of planar images obtained by PMCT was major and is not usable in practice at this moment, it may still be a useful tool if used in conjunction with other findings obtained by PMCT.