Role of Radiodiagnostic Imaging in Forensic Medicine

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

There has been an increase in the use of MRI in forensics in making a diagnosis when death involved either injury or disease. Stated to be one of the: "main criticisms of the use of MRI as an alternative to conventional autopsy is the lack of validation of this imaging technique." This is due to the mixed results that have been reported related to MRI post mortem examinations in the fields of neuropathology and paediatrics. According to Alderstein et al. (2001) who made comparison of MRI with autopsy results in perinatal cases. The report states: "MRI was not good at detecting major malformations such as cardiac anomalies."

Negative Findings in the use of Radiodiagnostic Imaging in Forensic Medicine

In an investigation in the UK a team researched the use of autopsies using MRI scans. Results stated that: "MRI was not able to accurately assess ischaemic heart disease..." The conclusions however, state that MRI use was "a credible alternative to autopsy....doctors only accurately certify the cause of death in 31-75% of cases, and that MRI autopsies were at least as good as that." Reported as well is by Roberts et al. (2003) were conclusions that the MRI was not able to (1) image coronary artery lesions (2) differentiate thrombus from post mortem clot; and (3) Differentiate pulmonary oedema from pneumonic exudates." Further stated is that "changes associated with decomposition...cause immense interpretive problems for radiologists." Bisset et al. (2002) states: "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."

II. Positive Findings in the use of Radiodiagnostic Imaging in Forensic Medicine

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 for the imaging of these objects in three-dimensional images in 'virtual space'. (Bruschweiler et al., 2003) Examined with this procedure are injuries of skin, soft tissue or bone in a patterned nature that allows matching "potentially incriminated instruments in shape, size and angle." (Bruschweiler et al., 2003)

The 3D imaging is performed through taking photographs in series. Next the computer will calculate the "position in space of certain points on the surface of the objects" (Bruschweiler et al., 2003) and at the same time produces 3D models of the objects being imaged. The pieces can then be manipulated such as in the manner of piecing together a puzzle for analysis and comparison and establishment of possible congruence.

Another technique that is new to forensic science is the application termed "Virtopsy." Virtopsy is used for the ability to image features of wounds and carry out post-image processing in 3D. (Forensic Medicine for Medical Students) It is stated by the Forensic Department at Bern University in Switzerland is: "Virtopsy was created for the purpose of implementation of "new techniques in radiology for the benefit of forensic science." Further stated is that: "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 minimally invasive "virtual" forensic autopsy." (Bern University Dept. Of Forensics, 2005)

Below are Figure 1.0: An example of 3D post processing of multi-slice CT imaging carried out by the Virtopsy team at Berne; and Figure 1.1: Pedestrian vs. car - another Virtopsy example

Source: Forensics Department - Berne Univeristy, Switzerland

Online available at http://www.forensicmed.co.uk/developments.htm]

Thali, et al. (2003) conducted a study through use of "postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI)" in 40 cases through examination with findings "verified by subsequent autopsy." (Thali et al., 2003) Classifications of results are (1) Cause of death; (2) Relevant traumatological and pathlogical findings; (3) Vital reactions; (5) reconstruction of injuries; and (6) Visualization." (Thali, et al., 2003)

47 causes of death (party combined) were stated in the examination of these forensic cases. Of those 25 or 55% causes of death were found through independent means with use of only radiological imaging data. Findings state: "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 in 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." These results, although preliminary in nature, "based on the concept of 'Virtopsy' are considered by the investigative group at Berne to be "promising enough to introduce and evaluate themes radiological techniques in forensic medicine." (Thali, et al., 2003)

Thali, et al. (2000) states in their work entitled "Improved Vision in Forensic Documentations: Forensic 3D/CAD-supported Photogrammetry of Bodily Injury External Surfaces Combined with Volumetric Radiologic Scanning of Bodily Injury Internal Structure" the conclusions that: "In the field of the documentation of forensics-relevant injuries, from the reconstructive point-of-view, the Forensic, 3D/CAD-supported Photometry plays an important role; particularly so when a detailed 3D reconstruction is vital. This was demonstrated with an experimentally-produced 'injury' to a head model, the 'skin-skull-brain model'. The injury-causing instrument, drawn from a real forensic case, was a specifically formed weapon."

The work of Bigler, et al. (2002 entitled "Observation and Identification of Metabolites emerging during postmortem Decomposition of Brain Tissue by Means of In Situ 1H-Magnetic Resonance Spectroscopy" the findings that when investigation of postmortem decomposition of brain tissue through use of 1H-magnetic resonance spectroscopy (MRS) was performed on a sheep head model and selected human cases "the inclusion of spectra of model solutions in the program LC Model confirmed the assignments in situ."

In the work of Thali, et al. (2003) entitled "New Horizons in Forensic Radiology: the 60-second digital autopsy-full-body examination of a gunshot victim by multislice computed tomography" states as its' goal of study being "the full-body documentation of a gunshot wound victim with multislice helical computed tomography for subsequent comparison with the findings of the standard forensic autopsy." (Thali, et al., 2003) Acquisitioned were "complete volume data of the head, neck and truck" (Thali, et al., 2003) in a matter of less than one minute of scanning time. The digital autopsy was quicker even with post-processing time added than the classic forensic autopsy. Findings state that advantages exist in comparison with the forensic autopsy of the tradition form based on the nondestructive approach.

Discussion

While the use of MRI, CAD, and other radiodiagnostic imaging in the filed of forensics medicine may not always be the optimal procedure to use it appears that there are certain procedures that the use of radiodiagnostic imaging has propelled to a new level of efficiency and accuracy in the field of forensic science.

This work has shown examples of procedures that without having the benefit of the use of radiodiagnostic imaging that much would be left to the imagination after the conduction of the traditional autopsy procedure.

This work has also given examples of new models being presently constructed for testing in the field and has shown as well the questions and criticisms that this type of diagnostic tool in forensics has surrounding it.

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 forensics medicine and that this type of diagnostic assistance in the field promises to…