Abstract:
Forensic pathologists commonly use computed tomography (CT) images to assist in determining the
cause and manner of death as well as for mass disaster operations. Even though the design of the CT
machine does not inherently produce distortion, most techniques within anthropology rely on metric
variables, thus concern exists regarding the accuracy of CT images reflecting an object’s true dimensions.
Numerous researchers have attempted to validate the use of CT images, however the comparisons have
only been conducted on limited elements and/or comparisons were between measurements taken from
a dry element and measurements taken from the 3D-CT image of the same dry element.
A full-body CT scan was performed prior to autopsy at the Office of the Chief Medical Examiner for the
State of Maryland. Following autopsy, the remains were processed to remove all soft tissues and the
skeletal elements were subject to an additional CT scan. Percent differences and Bland–Altman plots
were used to assess the accuracy between osteometric variables obtained from the dry skeletal elements
and from CT images with and without soft tissues. An additional seven crania were scanned, measured by
three observers, and the reliability was evaluated by technical error of measurement (TEM) and relative
technical error of measurement (%TEM).
Average percent differences between the measurements obtained from the three data sources ranged
from 1.4% to 2.9%. Bland–Altman plots illustrated the two sets of measurements were generally within
2 mm for each comparison between data sources. Intra-observer TEM and %TEM for three observers and
all craniometric variables ranged between 0.46 mm and 0.77 mm and 0.56% and 1.06%, respectively. The
three-way inter-observer TEM and %TEM for craniometric variables was 2.6 mm and 2.26%, respectively.
Variables that yielded high error rates were orbital height, orbital breadth, inter-orbital breadth and
parietal chord. Overall, minimal differences were found among the data sources and high accuracy was
noted between the observers, which prove CT images are an acceptable source to collect osteometric
variables.
