Radiodiagnostic Imaging in Forensic Medicine: Role & Uses

Introduction

The objective of this paper is to evaluate the role of radiodiagnostic imaging in forensic medicine and to critically appraise its use in forensic investigation.

There has been an increase in the use of MRI in forensics for making a diagnosis when death involves either injury or disease. One of the main criticisms of MRI as an alternative to conventional autopsy is the lack of validation of this imaging technique. This concern arises from the mixed results that have been reported in MRI post-mortem examinations in the fields of neuropathology and paediatrics. Alderstein et al. (2001) compared MRI with autopsy results in perinatal cases and reported that "MRI was not good at detecting major malformations such as cardiac anomalies."

Negative Findings in the Use of Radiodiagnostic Imaging

In a UK investigation, a research team studied the use of autopsies using MRI scans and found that "MRI was not able to accurately assess ischaemic heart disease." The conclusions, however, stated that MRI was "a credible alternative to autopsy," noting that "doctors only accurately certify the cause of death in 31–75% of cases, and that MRI autopsies were at least as good as that."

Roberts et al. (2003) concluded that MRI was not able to: (1) image coronary artery lesions; (2) differentiate thrombus from post-mortem clot; or (3) differentiate pulmonary oedema from pneumonic exudates. It was further noted that "changes associated with decomposition cause immense interpretive problems for radiologists."

Bisset et al. (2002) stated: "In cases of non-suspicious death, magnetic resonance imaging is a credible alternative to invasive autopsy. General practitioners and hospital doctors accurately certify only 31–75% of deaths; the six cases examined by both magnetic resonance imaging and autopsy suggest that imaging is at least as accurate."

Positive Findings in the Use of Radiodiagnostic Imaging

3D/CAD-supported photogrammetry is used in forensics (FPHG) as a method of "recording and documenting the surface of small objects" (Bruschweiler et al., 2003). This method allows injuries of skin, soft tissue, or bone to be imaged as three-dimensional models in virtual space. The patterned nature of these images allows for matching "potentially incriminated instruments in shape, size and angle" (Bruschweiler et al., 2003).

The 3D imaging process involves taking photographs in series, after which the computer calculates "the position in space of certain points on the surface of the objects" (Bruschweiler et al., 2003) and simultaneously produces 3D models of those objects. The resulting models can then be manipulated — much like assembling a puzzle — for analysis, comparison, and the establishment of possible congruence.

Another technique new to forensic science is "Virtopsy." Virtopsy is used to image the features of wounds and to carry out post-image processing in 3D. The Forensic Department at the University of Bern in Switzerland states that Virtopsy was created for "the implementation of new techniques in radiology for the benefit of forensic science." They further note: "There have been great improvements in MSCT and MRI technology, increasing both contrast and resolution and offering possibilities of 2D and 3D reconstruction. The aim is to establish an observer-independent, objective, and reproducible forensic assessment method using modern imaging technology, eventually leading to a minimally invasive 'virtual' forensic autopsy" (Bern University Department of Forensics, 2005).

Thali et al. (2003) conducted a study using postmortem multislice computed tomography (MSCT) and MRI in 40 cases, with findings verified by subsequent autopsy. Results were classified according to: (1) cause of death; (2) relevant traumatological and pathological findings; (3) vital reactions; (4) reconstruction of injuries; and (5) visualization. Forty-seven causes of death (partly combined) were identified across these forensic cases. Of those, 25 — or 55% — were found independently through radiological imaging data alone.

The study found that "radiology was superior to autopsy in revealing certain cases of cranial, skeletal, or tissue trauma. Some forensic vital reactions were diagnosed equally well or better using MSCT/MRI. Radiological imaging techniques are particularly beneficial for reconstruction and visualization of forensic cases, including the opportunity to use the data for expert witness reports, teaching, quality control, and telemedical consultation." Although described as preliminary, these results "based on the concept of Virtopsy are considered by the investigative group at Berne to be promising enough to introduce and evaluate radiological techniques in forensic medicine" (Thali et al., 2003).

Conclusion

It is the conclusion of this researcher that there is much left to be discovered through investigation and examination of the uses of radiodiagnostic imaging in the field of forensic medicine, and that this type of diagnostic assistance promises to bring about much positive effect in forensic diagnostic procedures. Certainly, more study is needed and worth pursuing in this area. As imaging technology continues to improve in contrast, resolution, and processing capability, its integration into forensic medicine is likely to expand — offering pathologists, investigators, and courts increasingly objective, reproducible, and detailed evidence.