The Virtual Autopsy

Forensic Magazine® | Articles | The Virtual Autopsy: The Doctor Will Scan You Now

The Virtual Autopsy: The Doctor Will Scan You Now Douglas Page August/September 2008 Advanced imaging tools such as MDCT are being used more and more in forensic medicine, sometimes beyond morgue walls. It may be too soon for a television series titled CSI: Radiology, but advanced imaging devices like multidetector computed tomography (MDCT) scanners are already accelerating changes in forensic medical science. MDCT technology is important to forensic investigators because it is fast, non-invasive, can obtain images without destroying the artifact, and can be used when conventional autopsy may not be feasible or where families may forbid conventional autopsy based on religious beliefs. (Multidetector CT scanners are similar in concept to original single-ring CT devices, except MDCT scanners have between 4 and 64 detector rings.) The technology even has wheels. In the first use of mobile MDCT for a mass fatality incident, researchers in England recently found that MDCT can be operational in temporary mortuaries within 20 minutes of arrival. Depending on the nature of the incident, three different imaging modalities may be required at conventional disaster morgues: fluoroscopy to screen victims prior to autopsy; plain x-ray for bone examination; and dental x-ray units to document dentition. MDCT provides an alternative or replacement for fluoroscopy and plain film x-ray within temporary morgues. “Our data suggest that CT may be adequate as the sole imaging investigation within a mass fatality mortuary,” said Guy N. Rutty, MD, of the Forensic Pathology Unit, University of Leicester. Rutty’s unit is the world leader in the area of mobile MDCT. 15-MINUTE PHOTO Rutty recently used a mobile MDCT scanner in a disaster mortuary established after a five vehicle fatal traffic incident. Five out of six bodies were successfully imaged by MDCT in about 15 minutes per body, compared to subsequent full radiological analysis of about one hour per case. http://www.forensicmag.com/Article_Print.asp?pid=220 (1 of 5)6/12/2009 2:31:32 PM

Forensic Magazine® | Articles | The Virtual Autopsy: The Doctor Will Scan You Now

Rutty’s mobile scanner was powered by diesel generators, but can also be plugged into the electrical grid. A truck transported the scanner and imaging suite, which included air conditioning, telecommunications facilities for remote radiology reporting, hard film printing, and CD burners for data storage. Usually, in the primary reception stage in a disaster morgue, fluoroscopy is used first to screen bodies and body parts, followed by further fluoroscopy or x-ray during identification, autopsy, or anthropological stages. “These can be time-consuming, rate-limiting procedures often requiring manual handling of both the bodies and equipment to insure adequate imaging,” Rutty said. Rutty demonstrated that a single CT modality can undertake both of these roles in a single stage, generating both soft tissue and bony images in antero-posterior, lateral, axial, and 3D views within a short time period. The scanner can examine single body bags or multiple fragment bags all at the same time without the bags being opened, which not only shields radiology technicians from disturbing sights, but also tends to maintain evidence continuity. “Since radiation dose is not relevant for the deceased, scanned images were obtained at the highest possible resolution to achieve the narrowest possible reconstructed slice thickness,” Rutty said. High resolution however introduces two potential problems. First, increasing resolution correspondingly increases heat load on the scanner, which can delay imaging while the unit cools. Secondly, high resolution increases the number and size of the image file, which can be an issue if the images are to be transmitted offsite to obtain a remote radiology report. Radiological findings in this incident followed a newly designed forensic CT reporting form that includes review of the muscular-skeletal system, cranium, facial bones, spine, axial, appendicular skeleton, central nervous system, cardiovascular system, respiratory system, airway, abdomino-pelvic organs, including upper GI tract, foreign bodies, and personal effects. “We identified the location of personal possessions and could even collect data related to articles of clothing, such as shoe tread patterns,” Rutty said. “We identified debris both on and in the bodies, which could be of evidentiary value.” Rutty said MDCT correctly identified the potential causes of death in all victims. Fractures were well seen and could be reconstructed in 3D. “In many cases, CT showed additional information not easily obtained by autopsy, such as stable fractures and nonhemmorrhagic brain injury,” he said. BE ALL YOU CAN SEE A 2007 military study found MDCT can also be used either to facilitate or reduce the need for conventional autopsy when drowning is the suspected cause of death. “Determining whether a person found dead in the water has actually drowned is imperative in forensic investigation because becoming submerged in water may be a secondary rather than primary event,” http://www.forensicmag.com/Article_Print.asp?pid=220 (2 of 5)6/12/2009 2:31:32 PM

Forensic Magazine® | Articles | The Virtual Autopsy: The Doctor Will Scan You Now

said COL. Angela D. Levy, MD, of the Department of Radiology, Uniformed Services University of the Health Sciences in Bethesda, Maryland. In Levy’s study, whole-body MDCT was performed immediately prior to routine autopsy in 28 male subjects who died of drowning. The control group was 12 male subjects who died of sudden death from coronary artery disease. Digital images were evaluated for such indications as the presence of fluid and sediment in the paranasal sinuses and airways, mastoid air cell fluid, frothy fluid in the airways, and pulmonary opacity. Image findings were then compared with findings from autopsy reports and photographs. The researchers concluded that MDCT finding of frothy airway fluid or high-attenuation airway sediment is highly suggestive of drowning, and that MDCT findings of pan sinus fluid, mastoid cell fluid, subglottic tracheal and bronchial fluid, and ground-glass opacity within the lung are supportive of drowning in the appropriate scenario. Levy said MDCT may provide support for the diagnosis of drowning when other causes of death have been excluded by a limited autopsy or external examination of the body. In addition to the MDCT-drowning paper, Levy has published studies of the utility of MDCT in gunshot wounds and fire deaths, work that has led many medical examiners to consider adding MDCT to their facilities. “MDCT speeds recovery of projectile and bullet fragments through precise localization of metallic fragments and aids in the detection of occult trauma,” Levy said. Certain areas of neck and deep pelvis are difficult to dissect. MDCT helps guide the forensic pathologist through these areas. “Also, MDCT is very helpful in the depiction and classification fractures in severe skull trauma,” Levy said. PICTURE THIS MDCT has also been shown to be effective in localizing gunshot wound tracks and to aid in forensic autopsies of gunshot wound victims. In forensic investigations of death by suspected projectile injury, plotting the projectile’s entry and exit locations, path, and associated tissue trauma can be important in determining the cause and manner of death. The Armed Forces Institute of Pathology has used MDCT as a non-invasive method to enhance forensic investigation in this area. “MDCT may guide, direct, or limit forensic autopsy in projectile injury cases, thereby eliminating the need for a complete invasive autopsy,” said H. Theodore Harcke, MD, of the Institute’s Department of http://www.forensicmag.com/Article_Print.asp?pid=220 (3 of 5)6/12/2009 2:31:32 PM

Forensic Magazine® | Articles | The Virtual Autopsy: The Doctor Will Scan You Now

Radiologic Pathology. In a 2007 study, Harcke compared MDCT to full-body digital radiography (DR) in the postmortem evaluation of gunshot wound victims. Thirteen consecutive male victims had full-body DR and MDCT prior to routine autopsy. According to Harcke, DR successfully identified all metallic fragments, but MDCT was superior in its ability to precisely determine location because it provided 3D anatomic localization. In all cases, MDCT more accurately assessed organ injuries and wound tracks. PICTURE OF STEALTH MDCT is even finding forensic uses outside of forensic medicine. Swiss researchers, for instance, have devised a way to detect smuggled dissolved cocaine using MDCT scanners. Smuggled dissolved drugs, particularly cocaine, in bottled liquids, is an ongoing problem at international borders. Common fluoroscopy of packages cannot detect contaminated liquids. Smugglers dissolve the drug and hide it in a few bottles of, say, wine, filling the remainder with uncontaminated liquid, making it easier to go undetected since border checks perform only random samples. “Our screening method can test all bottles rapidly and noninvasively,” said Silke Grabherr, MD, of the Institute of Forensic Medicine, University of Lausanne. Grabherr said the technique is suitable for the examination of large cargos or to confirm suspicions without compromising the packaging. Cocaine is a candidate contraband because it shows x-ray attenuation. Attenuation is the reduction in amplitude and intensity of a signal, such as an x-ray. “When a carton of wine bottles contains the same wine, the bottles will have more or less the same mean attenuation on cross-sectional images,” Grabherr said. “It should be considered suspicious when the attenuation of some bottles differs from the rest.” Grabherr said MDCT is applicable to other sorts of smuggling, such as contraband hidden inside small sculptures and hollowed fruit. “Using CT and measuring the mean opacity of the content, differences in hidden drugs can be detected without destroying the carrier,” she said. Grabherr isn’t necessarily recommending that expensive MDCT units be deployed at all border stations. “To employ our method, collaboration between police or customs officials and a medical department is necessary,” she said. Scanning can be performed at any facility with a CT scanner. “If a forensic chemistry department must analyze a confiscated shipment suspected of containing dissolved cocaine or other drug, the screening scan can be helpful to get a first overview to sort our suspicious vessels so more expensive quantitative chemical analysis can be performed on selected items,” Grabherr said. http://www.forensicmag.com/Article_Print.asp?pid=220 (4 of 5)6/12/2009 2:31:32 PM

Forensic Magazine® | Articles | The Virtual Autopsy: The Doctor Will Scan You Now

Douglas Page writes about forensic science and medicine from Pine Mountain, California. He can be reached at [email protected]. Copyright © 2009 Vicon Publishing, Inc.

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