Is Radiology Ready?
The efficacy of forensic postmortem computed tomography is no longer in dispute. What is still in question is whether radiologists proficient at interpreting clinical imaging of the living can be expected to be equally adept at rendering precise postmortem forensic findings without special training. There are major differences in the interpretation of postmortem and clinical imaging, yet no postmortem radiologic subspecialty exists.
Without special training, postmortem CT interpretations can easily be inaccurate. “A radiologist embarking on interpretation of postmortem CT or MRI is immediately aware that postmortem imaging is simply not the same as clinical imaging,” said Chris O’Donnell, MD, a radiologist at the Victorian Institute of Forensic Medicine, in Southbank, Victoria, Australia. Victoria is the world leader in postmortem CT usage. CT has been employed at the Institute over 10,000 times in the past five years.
There are many distinctions between imaging the dead and imaging the living. O’Donnell said established techniques of oral and intravenous contrast administration are not possible with the deceased, thus interpretation of thoracic and abdominal cavities is problematic.
“Also, bodies are often not positioned orthogonally on the scan table due to rigor, anatomy can change dramatically in shape due to lack of blood pressure, blood elements sediment out after circulation ceases, and lividity and intravascular clot is seen as a normal change after death,” he said.
The process of decomposition and putrefaction leading to abnormal gas formation can be confusing and lead to incorrect diagnosis if not fully understood, he said. There is still debate about the origin and distribution patterns of this gas and the contributions of trauma, cardiopulmonary resuscitation, and putrefaction to the presence of such gas.
“Pathologies rarely seen in the living are commonplace to the forensic pathologist and must also be recognized by the radiologist,” O’Donnell said. In addition, forensic pathological terminology differs from that used in the clinical field. Radiologists and forensic pathologists also approach injury cause and effect from different directions.
“The clinical radiologist is very much concerned with the visceral effects of trauma, such as identifying sites of tissue disruption and hemorrhage in order for appropriate treatment to be instituted, whereas issues of causation are paramount to the forensic pathologist, who must decide how injury has occurred and the mechanisms of that injury, as well as the ultimate effect,” O’Donnell said.
The bottom line is, clinical radiologists seldom exposed to postmortem cross-sectional imaging are at risk of misinterpreting postmortem findings, particularly if they adhere to the rules of clinical radiological analysis.