Jonathan Ford

Virtual Determination of Sex: Metric and Nonmetric Traits of the Adult Pelvis from 3D Computed Tomography Models

Abstract:  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.

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 FBIs ReFace) and two manual reconstructions (completed by FBIs Neville and Faraut) were completed using a skull from a known individual. A living individuals 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.

A simple method of nose tip shape validation for facial approximation

Despite numerous papers relating to the prediction of nose projection for the purposes of facial approximation, there is little guidance for nose tip shape that has been evaluated on a known data set. This study presents a novel, simple technique for validation of the reconstructed nose tip shape based on methods used in actual approximation practice. The data set was comprised of 25 full-head computed tomography (CT) patient scans. In 22 of the 25 patients across all age and sex groups, when the head is tilted so that soft tissue pronasale is superimposed on hard tissue rhinion, the curvature of the nose tip was found to mimic the curvature of the superior portion of the nasal aperture. This occurs when the head is tilted dorsally by approximately 60° (55.87±5.91). Individuals with snub noses presented a much wider tip curvature. The method was highly repeatable and was evaluated through inter- and intra-observer studies (error=3.15%).

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.

Management of 3D Image Data

Previous chapters in this text have demonstrated some of the applications of three-dimensional (3D) imaging capture methods including medical imaging (X-ray/CT/MRI), 3D surface or laser scanning, 3D photography, and microscopy. This chapter will discuss what exactly 3D data is filewise and what information is embedded in those files. It will also make recommendations as to how to efficiently manage 3D image data and store it. Additionally, forensic researchers and practitioners will be made aware of some of the security issues they may face when working with sensitive 3D image files.

Anastomotic Airway Complications After Lung Transplant: Clinical, Bronchoscopic and CT Correlation.

The purpose of this article is to review the normal appearance and common complications of the airway anastomosis in lung transplant patients with emphasis on computed tomography images with bronchoscopic correlation. The spectrum of complications will be presented as early (<1 mo after transplant) or late (>1 mo). Variations in surgical technique as well as presentation and management options for airway complications will also be discussed.