Who is this person? A comparison study of current three-dimensional facial approximation methods.

Facial approximation is a common tool utilised in forensic human identification. Three-dimensional (3D) imaging technologies allow researchers to go beyond traditional clay models to now create virtual computed models of anatomical structures. The goal of this study was to compare the accuracy of available methods of facial approximation ranging from clay modelling to advanced computer facial approximation techniques. Two computerised reconstructions (FaceIT and FBI's ReFace) and two manual reconstructions (completed by FBI's Neville and Faraut) were completed using a skull from a known individual. A living individual's computed tomography (CT) scan was used to create a virtual 3D model of the skull and soft tissue of the face. The virtual skull models were provided to the computer-based approximation specialists. A rapid prototype of the skull was printed and provided to the practitioners who needed physical specimens. The results from all of the methods (clay and virtual) were compared visually to each other and collectively to the actual features of the living individual to compare the results of each. A quantitative study was also conducted to establish the accuracy of each method and the regions of the face that need the most improvement for all of the specialists. This project demonstrates the wide range of variation between commonly used facial identification methods. The benefit of this study was having a living individual to test the strengths and weaknesses of each method while also providing future areas of focus for soft tissue depth data studies.

Third sacral foramina morphometry for sacral neuromodulation.

OBJECTIVE: This study is aimed to define the geometry and location of the human S3 foramen, with respect to bony landmarks visible on ultrasound. METHODS: Computed tomographic (CT) image data from an institutional review board-approved database of de-identified pelvic CT images were analyzed. Points along the S3 foramina and bony sacrum were tagged, and their locations saved. The saved points were mathematically analyzed to determine the geometry and relative location of the S3 foramina with respect to other bony landmarks, specifically the sacral hiatus, and the sacral spinous processes, and the caudad aspect of the bilateral SI joints ("SI line"). Descriptive statistics were used to describe the geometry and aggregate location of the S3 foramina bilaterally. CT data sets were excluded if they had evidence of pelvic bone injury, prior bony fixation, severe osteoporosis, or other deformity. RESULTS: One hundred thirty-three data sets met the inclusion criteria. The SI line was superior to the sacral hiatus for reliable S3 localization. The entire circumference of approximately 14% of the S3 foramina is located cephalad to the SI line. The sagittal angle of trajectory for S3 was approximately 70 degrees relative to the dorsal surface of the sacrum. CONCLUSIONS: Clinical localization of the S3 foramen for sacral neuromodulator needle placement is best obtained when the needle tip is positioned 15 to 25 mm lateral to the sacral spinous processes and 0.0 cm to 25 mm caudad to the SI line, at the level of the dorsal sacrum surface. The findings presented in this study may be applied to improve the efficacy and accuracy of neuromodulator lead placement into the S3 foramen. This study provides rationale for the effectiveness of the crosshair placement technique and demonstrates the best location for needle repositioning when this technique is not initially successful.

Virtual determination of sex: metric and nonmetric traits of the adult pelvis from 3D computed tomography models.

Examination of the adult os coxae and sacrum is one of the most common methods of sex estimation from bone. Medical imaging, such as computed tomography (CT), provides the opportunity for three-dimensional (3D) imaging of the skeleton from clinical scans of known individuals in situ. In this study, a randomly selected subset of abdominopelvic CT-derived models were used to evaluate simple, repeatable metric methods of sex estimation based on a combination of obstetric measurements and the traditionally nonmetric Phenice-derived traits. A four-variable discriminant function for sex estimation was developed based on statistical analyses. Overall, the cross-validated accuracy of this method was 100%, with inter-observer error showing an average of only 2.2%. Comparative analysis was run on the data set using FORDISC 3.0. This study shows that current sex determination standards from the pelvis should be updated to include more in vivo data to increase the accuracy of identification.