THE HISTORY OF FORENSIC IMAGING
The x-ray was discovered in 1895 and the first forensic application of this technology occurred in the same year when it was used to localize projectiles. Over the ensuing years radiographs were fully integrated into the daily practice of forensic pathology and became required for medical examiner accreditation.
X-ray computed tomography (CT) was developed in 1974 as the progeny of the x-ray and allowed a series of 2-dimensional images to give a 3-dimensional perspective. CT technology advanced rapidly from acquiring sequential slices to complete volumes at high resolution (spiral CT with multiple detectors) that could be reconstructed in multiple planes. Advances in computer processing and data storage embodied in Picture Archiving and Communication Systems (PACS) led to “filmless” technology and allowed for the on-the-fly review of thousands of images including multiplanar and 3-dimensional reconstructions.
Magnetic resonance imaging (MRI) scanners were also developed in the 1970's and became integrated into the practice of medicine in the 1980's. This technology uses a magnetic field created by a strong magnetic coil to align the body’s hydrogen protons and radiowaves to excite the protons so that they emit radio waves. The differences between how the protons in different tissues are excited and emit radiofrequencies create images. These images are also reviewed with PACS workstations.
While clinical medicine was quick to evaluate and adopt these technologies forensic pathology was slower to follow suit largely because of inadequate governmental budgets and a perception that autopsy was the “gold standard.” Nevertheless, both CT and MRI technologies were first applied to forensic autopsy in a limited way in the 1990's and their usefulness continued to be evaluated into the 2000's to the present. However, studies were hampered by small size and limited design (e.g., not blinded and autopsy used as gold standard rather than autopsy + advanced imaging modality). These early studies yielded inconsistent evidence about the utility of postmortem CT in recognizing injuries and identifying the cause of death. At a minimum, however, CT was determined to be a useful adjunct for forensic autopsy. In general, CT is better for evaluating bones and MRI is better for evaluating soft tissues.