CT divulges clues for forensic investigators
Caren B. Les
Researchers have shown that a “virtual autopsy” performed with multidetector CT can help identify drowning as a primary cause of death. The virtual technique could assist forensic investigators in determining whether the cause of death for a body found in water was drowning or whether the body became submerged in water as a secondary event. The method could complement — or reduce the need for — an autopsy when drowning is suspected. Also, the noninvasive procedure does not damage or destroy forensic evidence.
Dr. Angela D. Levy of the Uniformed Services University of the Health Sciences in Bethesda, Md., the lead author, and scientists from the University of Maryland School of Medicine in Baltimore and from the Armed Forces Institute of Pathology in Washington and Rockville, Md., conducted a study to compare virtual autopsy images with conventional autopsy results.
Multidetector CT images show the upper airway and sinus characteristics of drowning. The transverse image (left) at the level of the mastoid air cells shows patchy fluid within the cells (black arrows) and frothy fluid in the nasopharynx (white arrow). The sagittal image (right) shows frothy fluid filling the posterior nasal cavity, nasopharynx and oropharynx. Images reprinted with permission of Radiology.
They performed total body multidetector CT immediately prior to routine autopsy in 28 male subjects (mean age 24.2 years) who had drowned. Both procedures were performed two to 12 days following death. They also performed imaging and autopsy, two to seven days following death, on a control group of 12 male subjects (mean age 50.8 years) who died suddenly of atherosclerotic coronary artery disease.
All subjects were imaged with a whole-body multidetector CT from GE Medical Systems, using no contrast material. Images were obtained from the skull vertex to distal femur or proximal tibia and fibula and from the distal femur to the toes. The images were evaluated for the presence of fluid and sediment in the paranasal sinuses and airways, for mastoid air cell fluid, for frothy fluid in the airways, for pulmonary opacity, for interlobular septal thickening, and for gastric distension and contents (fluid or sediment).
A transverse multidetector CT of the head (left) shows high-attenuation sediment in the sinuses; a multidetector CT of the chest (right) shows fluid-filled bronchi with sediment (arrows).
The researchers then compared the CT image findings with the conventional autopsy reports and photographs. They determined that finding frothy airway fluid or airway sediment through the multidetector CT method indicates drowning as the primary cause of death, according to Levy. There was no evidence of either substance in the airways of the control subjects. Results also indicated that “virtual autopsy” findings of pansinus fluid, mastoid cell fluid, subglottic tracheal and bronchial fluid, and ground-glass opacity within the lung also may support drowning as the primary cause of death, if the indications are in keeping with the relevant circumstances.
Levy said that the investigators also have found the virtual technique to be useful in traumatic causes of death, such as in gunshot wounds. She added that the group is studying many areas of the CT application to autopsy, including other causes of death and, in general, improving autopsy in anatomic areas that are difficult to assess by dissection.
Radiology, June 2007, pp. 862-868.
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