Michael J. Thali

Forensic radiology with cross-section modalities: spiral CT evaluation of a knife wound to the aorta.

We describe the extraordinary case of a penetrating knife wound to the aorta. The localization of the tip of the knife was documented with a Computed Tomography examination and subsequent two- and three-dimensional reconstruction. Based on this case report, the utilization of computed tomography in forensic science and its potential for vizualization are discussed.

Evidential value of postmortem MRI in forensic pathology

We currently evaluate MRI as add-on to dissection. Cases can only build on high evidential values of morphological findings as estimated using Bayesian likelihood-ratios. These values may vary among different cases depending on the quality of the morphology and the discrete hypotheses to be discerned. After scanning 20 bodies using MRI admitted to our institute for autopsy, we reconstructed selected imaging findings from a couple of illustrative cases according to a geometrical model (Pink Box) designed as an object oriented bridging protocol to enable comparison of autopsy and MRI data. Although it appears obvious that three-dimensional imaging yields relevant diagnoses, comparison of selected findings suggests, that the real evidential value of a postmortem scan depends on basic geometrical features of tissue structures examined. (1) Tissue surfaces are difficult to examine in MRI, including surface features of contact wounds in firearm injuries, lacerations of the pleura, or skin needle marks. (2) Specificity and sensitivity of solid tissue block data depend on contrast and resolution. (3) Tunnels or tubes, such as coronary arteries, linear wound tracks or the aorta offer more degrees of freedom for reconstruction, including spatial reconstruction or cross sectioning in different directions. (4) Three-dimensional rendering of complex objects results in spectacular images. Their evidential value is dependent on the way thresholding of 2D slices is validated. We present illustrative examples which suggest that a possible integration of non-invasive imaging methods into Forensic Pathology in fact need to take basic geometry into consideration when discussing evidential value.