Computed tomography of contrast-filled stab wounds in various tissue types

Abstract

Background Stab wounds are common in homicide cases. Post-mortem multislice computed tomography (MSCT) has proved to be a useful tool in forensic examinations of victims of sharp force trauma. In this study, we have obtained information about the shape of a knife blade by CT scanning contrast-filled experimentally inflicted stab wounds in various types of pig tissue. Method Tissue samples from lung, liver, kidney, spleen and skeletal muscle were mounted on floral foam (oasis) with wooden sticks and stabbed with five different types of knives and a screwdriver. The stab channels were filled with contrast medium and CT-scanned. Two contrast media were used: one was unmodified and easy flowing, and one was made more viscous with polyethylene glycol. Stab channels in ballistic soap were used for comparison. India ink-filled stab channels were investigated histologically to determine the pattern of leakage. Results The shape of the stab wounds on the CT images from lung and muscle tissue did not correspond well to the shape of the inflicting knife. There was a better correspondence in the images obtained from liver, spleen and kidney. The viscous contrast medium was less likely than the thin (easy flowing) contrast medium to spill into to structures outside the stab channel, but some spillage was observed for both types of contrast medium. Air bubbles were only observed in the viscous contrast medium. Conclusion Radiological evaluation of a contrast-filled stab wound in isolated tissue blocks did not permit the positive identification of the inflicting weapon, but in liver, spleen and kidney a rough idea of the shape of the inflicting knife could be obtained and it was possible to differentiate a knife from a screwdriver.