Global illumination rendering versus volume rendering for the forensic evaluation of stab wounds using computed tomography.

We compared three-dimensional (3D) CT images of stabbing victims subjected to volume-rendering (VR) or global illumination-rendering (GIR), a new technique now available for the reconstruction of 3D CT images. It simulates the complete interactions of photons with the scanned object, thereby providing photorealistic images. The diagnostic value of the images was also compared with that of macroscopic photographs. We used postmortem 3D CT images of 14 stabbing victims who had undergone autopsy and CT studies. The 3D CT images were subjected to GIR or VR and the 3D effect and the smoothness of the skin surface were graded on a 5-point scale. We also compared the 3D CT images of 37 stab wounds with macroscopic photographs. The maximum diameter of the wounds was measured on VR and GIR images and compared with the diameter recorded at autopsy. The overall image-quality scores and the ability to assess the stab wounds were significantly better on GIR than VR images (median scores: VR = 3 vs GIR = 4, p < 0.01). The mean difference between the wound diameter measured on VR and GIR images and at autopsy were both 0.2 cm, respectively. For the assessment of stab wounds, 3D CT images subjected to GIR were superior to VR images. The diagnostic value of 3D CT GIR image was comparable to that of macroscopic photographs.