Virtual CT morphometry of lower limb long bones for estimation of the sex and stature using postmortem Japanese adult data in forensic identification.

The application of computed tomography (CT) is useful for the documentation of whole-body anatomical data on routine autopsy, virtual reconstruction of skeletal structure, objective measurements, and reassessment by repetitive analyses. In addition, CT data processing facilitates volumetric and radiographic density analyses. Furthermore, a recently developed automated analysis system markedly improved the performance and accuracy of three-dimensional (3D) reconstruction. The present study investigated virtual CT morphometry of lower limb long bones, including the femur, tibia, fibula, and first metatarsus, to estimate the sex and stature using postmortem CT data of forensic autopsy cases of Japanese over 19 years of age (total n = 259, 150 males and 109 females). Bone mass volumes, lengths, and total CT attenuation values of bilateral femurs, tibias, and fibulas correlated with the stature; however, the mean CT attenuation (HU) values showed age-dependent decreases. Correlations with the stature were similar for the lengths and mass volumes of the femur, tibia, and fibula (r = 0.77-0.85) but were higher for the mass volume of the first metatarsus (r = 0.77 for right and r = 0.58 for left). In addition, the ratio of the bone volume to the length of each bone showed the most significant sex-related differences (males > females with accuracy of 75.8-98.1 %). These findings indicate the usefulness of virtual CT morphometry of individual lower limb long bones, including volumetry, to estimate the sex and stature in identification.

Efficacy of automated three-dimensional image reconstruction of the femur from postmortem computed tomography data in morphometry for victim identification.

Besides conventional radiology, postmortem computed tomography (PM-CT) is nowadays widely used for victim identification in forensic routines to detect anatomical characteristics and specific pathologies as well as to estimate the stature and sex. A major advantage of PM-CT is virtual reconstruction of skeletal structures independent of the status of recovered remains. The present study investigated the efficacy of a recently provided automated analyzer to reconstruct three-dimensional (3-D) images using CT data for skeletal morphometry, measuring the whole bone mass volume of the femur (60 bones in 30 cases) as an index of reproducibility. Manual cursoring could reconstruct bilateral femurs with high reproducibility, showing mass volume fluctuations by repetition and between two independent observers of 0.2-2.1% and 3.5-6.7%, respectively, partly depending on the data analysis system, but was time-consuming, while automated reconstruction was very rapid and highly reproducible virtually without detectable fluctuation; there was a high correlation between bone mass volumes reconstructed by manual and automated procedures (r=0.9976, p<0.0001). The reproducibility of the automated procedure was 98.64-100.81% in 5 cases scanned twice under the same CT conditions. Preliminary analysis showed a substantial correlation of the whole femur mass volume with the body height and a significant sex-related difference in the femur mass volume/body height ratio (males>females). These findings indicate the accuracy and practical feasibility of the automated procedure to reconstruct single bone 3-D CT images for virtual skeletal morphometry in victim identification.