Background: The sudden, unexpected death of young persons from ruptured thoracic aortic dissection is suggestive of Marfan syndrome (MFS), a genetic disorder of fibrillin. Establishing such a diagnosis is important so that the same fate might be avoided in living relatives. MFS diagnosis is difficult in the deceased but the presence of arachnodactyly, a common morphological feature of MFS, can be established by assessing the metacarpal index (MCI). MCI is routinely determined using radiographic techniques including computed radiography (CR). The wider availability of computed tomography (CT) in the forensic environment provides an alternative method. CT is predicted to produce measurements at least as accurate as CR. The aims of this study therefore were to (1) validate MCI measurements by comparing CT and CR with direct measurement using calipers on human skeletonised hands, and (2) compare cadaveric CT and CR MCI measurements.
Methods: The metacarpals of 12 human skeleton hands were measured using CT and CR, and compared with direct measurement using calipers (the "gold standard"). Fifty randomly selected cadavers between 20 and 40 years had the MCI of both hands measured using CT and CR.
Results: CT was found to be more accurate in the measurement of MCI than CR. There were significant differences in the MCIs obtained for CT and CR (females: p=0.01; males: p<0.0001) and between CR and calipers (p=0.004). There were no significant differences between MCIs obtained for CT and calipers (p=0.71). CR was found to consistently overestimate the MCI by an average of 7.97%.
Conclusion: CT is more accurate in determination of the MCI than CR and should provide the basis for future skeletal measurements.