X-ray detectives turn images into evidence

Eight years ago, nationalist Bosnian Serb forces entered the town of Srebrenica, a United Nations "safe area." Serbian troops separated men living in the Bosnian town from their mothers, wives, and children, who then fled to Muslim-controlled areas of Bosnia to await their relatives' eventual return. But as the weeks and months passed, the expected reunions never happened. Over 7500 former inhabitants of Srebrenica had simply disappeared.

The horror of what had happened in Srebrenica, and other towns like it, began to become clear with the discovery of mass graves, followed by a series of exhumations and lengthy postmortem examinations. Now evidence provided in part by radiologists is helping these families face the future equipped with knowledge of what happened to their loved ones.

Through cases obtained not only in the Balkans but in Africa, Central America, and the Middle East, forensic imagers are building a collection of diagnostic signs that point to a range of fatal and nonfatal types of violence.

BALKANS MISSION

Mark Viner, radiology services manager for Barts and the London NHS Trust in the U.K., has taken the lead in organizing radiographic services for the U.N.'s International Criminal Tribunal for the former Yugoslavia (ICTY). His involvement with the ICTY dates back to a chance phone call in 1996 from a former colleague and member of Physicians for Human Rights. The Boston-based group had been asked to initiate forensic examinations of war crimes in Bosnia and Croatia.

"They were using fluoroscopy and had managed to get some U.S. technologists (radiographers) and one radiologist to go over, but they were having real difficulty getting people," Viner said. "I just put up a notice for our radiographers that said: 'Is anybody interested in going?' We ended up with a whole list of people."

Radiographers trained in anatomy and physiology began working in conjunction with specialists collecting archeological, anthropological, and pathological evidence. Viner returned to work with the ICTY forensic teams in Bosnia, Croatia, and Kosovo two or three times a year and coordinated an international team of radiographers for the project until its completion. He has also assisted U.N. peacekeeping troops in Sierra Leone with another forensic investigation and helped fulfill the steady demand from other U.N. organizations for forensic radiographers in Kosovo. Local radiology personnel have been reluctant to get involved with investigations, thwarting attempts to instigate a home-grown forensic radiography workforce.

A key part of Viner's role has involved advising the U.N. on the imaging equipment needed for the temporary mortuaries. Exhumed body bags must first be screened using fluoroscopy, and the precise locations of all artifacts recorded before the remains are sent for autopsy. Skulls found in the opened body bags may then be x-rayed for comparison purposes with missing persons' dental records. Radiographers may also take plain films of body parts and complete corpses, recording previous fractures and medical implants. This again helps with identification and can also provide clues as to the cause of death.

The first year had a steep learning curve for all involved. Radiographers had been provided with lead aprons and thyroid shields, Viner said. He managed to persuade a company to donate a small LCD radiation dosimeter. Imaging equipment borrowed by the U.N. was affected by voltage fluctuations in the local electricity supply, and processing chemicals had to be mixed and heated by hand.

With equipment troubles eventually sorted out and reproducible protocols in place, radiographers have made a valuable contribution to ICTY investigations. Initial fluoroscopy screening of body bags prevented pathologists from harming themselves on unexpected sharp objects-or worse: Forensic radiographers have on rare occasions found unexploded grenades.

Imaging has also helped establish the cause of death and determine who was responsible. Bullets or shrapnel detected on x-rays can be located, retrieved, and matched to known weaponry. The shape of wounds and pattern of fragments left by ammunition can also indicate how an individual died. But when the bodies have been buried for many years, exhumed, and then reburied with other corpses, finding this evidence is not easy.

"If all you've got left is a bag of bones, you're probably not going to find a bullet, even if it was in the soft tissues at the time of burial," Viner said. "You can usually tell if there is a gunshot wound and determine whether it's an entry or an exit wound, but without the presence of a bullet or bullet fragments it is not easy to demonstrate. Sometimes you can get very minute traces of bullet fragment embedded within the bones. The only way you're going to demonstrate that is on an x-ray."

Problematic cases could actually reinforce the importance of radiological input in the endeavor, said Wayne Hoban, superintendent radiographer at the Royal Free Hospital in London, who has also played an important role in linking U.K. radiographers with U.N. forensic teams in the Balkans. On one occasion, pathologists failed to find a bullet during dissection that had shown up clearly on x-ray.

"I had a look at the x-ray I'd taken, and from that I was able to go to the body and point to where the bullet should be. And they found it exactly where I'd pointed," he said. "They realized that I had expertise that they didn't have, and it was quite rewarding to feel that I was doing something that was actually useful."

Radiographers also had to deal with difficulties arising from the location of their work. Mortuaries in former war zones, for instance, caused certain complications. Toni Meyer, now a lecturer in diagnostic radiography at the University of Hertfordshire in Hatfield, U.K., worked a four-week stint as a forensic radiographer in Kosovo in June 2000, investigating events surrounding the NATO bombing of what turned out to be a civilian tractor convoy. The fighting had ended, but the area was still under military control. U.N. forensic team members were advised to take precautions such as keeping a two-week supply of food and water at their residency, learning emergency evacuation procedures, and adhering to a strict midnight curfew.

"You would have a radio in the house so you could stay in contact with the U.N. There were revenge attacks going on and houses being burned down in the night, but mainly in the town centers. Then there was the huge problem of mines and unexploded ordnance. The day you arrive you go straight to training to learn how to avoid getting injured by a mine," Meyer said.

Extremes of weather posed practical difficulties. Temperatures soared in the summer, making mortuary work wearing a lead apron extremely uncomfortable, and then plummeted in the winter months. Teams of ICTY investigators in Bosnia worked from April to October, although these seasonal boundaries were not followed on all projects.

Nick Crohn, a radiography lecturer-practitioner for the Hull and East Yorkshire NHS Trust in the U.K., arrived in Kosovo in mid-November 2002 and stayed until early December. Electricity was available for just one hour in five, leaving investigators reliant on their own generator, and the mobile image intensifier stopped working in the intense cold.

"The unit was guaranteed for temperatures between 10 degrees and 40 degrees C," Crohn said. "At one point, it was -4 degrees C inside, and the unit wouldn't work until it had warmed up."

Despite these difficulties, radiographers collating material under the auspices of the U.N. recognized the importance of adhering to well-defined procedures. Deviation from proper imaging protocols, errors in official paperwork, or damage to physical evidence could have rendered their evidence worthless. Hoban admits that at times the sheer scale of the task faced by the forensic teams working with mass graves and severely decomposed remains made the radiological evidence seem like mere "window dressing." Feedback received later, however, convinced him that their efforts were worthwhile.

"I knew that the evidence we produced would end up in the international court in The Hague, and that really makes you think. If even one of my x-rays succeeds in convicting someone who is guilty, I would say that is a success," he said.

UNUSUAL EVIDENCE

Prof. Dr. Hermann Vogel, a consultant radiologist at the St. Georg General Hospital in Hamburg, Germany, is similarly aware that radiological evidence can have far-reaching consequences. As the x-ray specialist in maxillary surgery at the Hamburg hospital during the 1980s, he was asked to examine a group of Iranian soldiers who had been fighting in the war with Iraq and required reconstructive facial surgery. During their hospital stay, it became clear from lung x-rays that the group had also been involved in chemical warfare. The Iranian government was effectively trying to use the authority of independent medical records to certify Iraq's use of illegal weaponry, Vogel said.

"You must always look at how the information you furnish will be used by somebody else," he said. "This is a danger when you work in this field. You always have to consider the instrumentalization of your work, your results."

Vogel traces his appreciation of radiology's power as a forensic tool back to a visit he made to Rhodesia (now Zimbabwe) during the mid-1970s. The trip was part of a study tour to collect material for a planned book on tropical diseases. While looking through the x-ray archive at a large hospital in Salisbury (now Harare), however, he observed something strange about the injuries recorded on film.

"I noticed that the x-ray findings did not fit with the information that I had got beforehand from the German embassy, international newspapers, and TV reports. The dates and the facts that were documented by the x-rays didn't match," he said. "I noticed that sitting in the archive of an x-ray department I could get information that hardly anybody else had."

The images revealed patterns typical of high-velocity gunshot wounds, evidence of explosives, and the use of multiple arms, including a tail fin rocket, Vogel said. This contradicted reports of fighting between organized armies during the war against white minority rule that ended in 1979, in which case x-rays would have revealed a different, more uniform set of lesions. Instead, radiological records indicated that injuries were due to civilian combat.

His hunch turned out to be correct. Subsequent discussion with hospital staff revealed that the casualties had been attacked at random while traveling in a convoy through the suburbs of Harare. Encouraged by the results of his radiological detective work, Vogel began to investigate how medical images could clarify, classify, and corroborate acts of violence. Now almost 25 years later, his detailed research has revealed exactly how x-ray, ultrasound, CT, and MRI data can identify differing forms of combat, trace the use of illegal arms, and offer evidence of torture (Brogdon BG, Vogel H, McDowell JD. A radiologic atlas of abuse, torture, terrorism, and inflicted trauma. Boca Raton, LA: CRC Press, 2003).

The highly sensitive nature of this work means that research can be fraught with danger. Publication of articles on Vogel's findings led to a warning for him to stay away from certain countries. Vogel has learned to recognize signs of trouble and avoid situations where his actions may compromise the safety of his contacts. He described a visit to a hospital radiology department in a country that had been embroiled in war for 50 years.

"I had noticed beforehand that every person who wanted to talk to me on a personal matter only did it with the radio turned up to maximum noise," he said. "I didn't pay much attention in the beginning. Then I went to another hospital and the colleague I was speaking to gave me a sheet of paper, on which was written: 'We are overheard. Be careful.'"

The use of radiological evidence in demonstrating war crimes will differ depending on the nature of the illegality, according to Vogel. Some forbidden firearms produce a characteristic x-ray pattern. So-called dum dum bullets, first used by British troops in India and the Sudan during the late 1890s, expand on impact, causing significant internal injuries. But x-ray findings associated with this illegal ammunition should not be confused with those produced by high-speed bullets. These modern-day bullets produce a similar effect in tissue due to hypersonic shock, but they are perfectly legal.

Chemicals and shock

Imaging demonstration of chemical or germ warfare is more problematic. Unusually high incidence of emphysema-type findings could indicate past exposure to chemical agents, Vogel said. Observation of pulmonary edema in patients who had survived a gas attack might also help confirm deployment of chemical agents that penetrate the skin, such as VX gas. DNA and microbiology tests, however, would more likely be used to confirm inhalation of anthrax or plague spores.

Imaging has a significant role to play in cases of torture. The use of falaca, in which victims are beaten on the soles of their feet, is still reportedly practiced in a number of countries. X-rays can detect characteristic bone fractures, blood, and edema in the acute phase. MRI may reveal the resultant tendon thickening and ulcerations when initial signs of injury have disappeared.

MRI has also been used to confirm claims of electric shock torture by identifying signs of tissue damage where electrodes were attached to victims' extremities. Perpetrators of this act, however, have responded to imaging detectives' success by altering their methods. Reports from Turkey indicate that torturers have switched to using electrodes with larger pads to avoid creating localized areas of tissue damage, Vogel said. Yet radiologists may still outwit the torturers. Sophisticated diagnostic imaging techniques might be able to demonstrate muscle ulcerations induced by the electric current if victims are examined shortly after their ordeal.

Evidence of brutality has also surfaced in images captured by forensic radiographers in the Balkans. Most imaging work at the temporary mortuaries followed a predictable routine. On occasion, however, the 2D black-and-white views illustrated the harrowing circumstances in which civilians had died. X-rays revealed bullet holes in knees and elbows, and through the back of the skull. Electric cables and barbed wire, used as crude forms of restraint or garrotes, also showed up clearly on initial imaging. Such findings can leave a lasting impression on even the most experienced healthcare professional.

"I don't think anything can prepare you for this sort of experience," Crohn said. "The best thing to take is an open mind, a willingness to learn from others, and an ability to work as part of a team. We all cried at times, but we were able to laugh as well, and to talk together as part of a team."

Ms. Gould is associate editor of Diagnostic Imaging Europe, a sister publication to Diagnostic Imaging.