Scanning the Dead

Even though his story is like something out of a procedural crime drama – one of those long-running, ensemble whodunits like “Law & Order” or “CSI” – Barry Daly, MD, doesn’t have much time for television.

“They cut a few corners when it comes to the science,” Daly says, “although there’s a certain amount of artistic license involved.”

A professor of radiology at the University of Maryland (UM) School of Medicine in Baltimore, Daly’s chief area of research is the emerging field of forensic imaging, or virtual autopsy.

And he likely doesn’t have time for David Caruso and Sam Waterston because his investigations aren’t scripted with fulminating courtroom confrontations, teary confessions or alleyway “gang-banger” gun battles. In the world of virtual autopsy, professionals can generate results within 30 minutes – and without the interruption of commercial breaks.

A Century-Long Legacy

Daly’s career in radiology began in Dublin, Ireland, in 1983, when techniques, such as ultrasound and nuclear medicine, revealed the emerging promise of the field. Although Daly had always had a passing curiosity for forensics, he hadn’t known its relationship to his chosen profession is as old as radiology itself.

A lecture by Byron G. Brogdon, MD, distinguished professor emeritus of radiology at the Mobile-based University of South Alabama Health System, illuminated for Daly the years that had been devoted to the marriage of medical imaging and detective work. Brogdon’s book, Forensic Radiology (CRC Press, 1998) was a further inspiration to Daly’s own research in pairing medical inquiry and imaging techniques.

“[Brogdon] gave a tremendous account of the history of forensic radiology that dated back to the time of [Wilhelm] Roengten himself,” says Daly. “Within a year of Roentgen’s discovery in 1895, X-rays were being taken in the United States to identify foreign bodies and ballistics reports. [Brogdon’s] book collects some wonderful stories about how radiology was used to determine whether diamonds were false or real, that sort of thing,” says Daly.

Whereas Brogdon’s historical accounts demonstrated a fundamental connection between the forensic and radiological sciences that spans more than 100 years, Daly’s specific interest – using CT and MR techniques to help autopsy a body – is a tradition that originated about 20 years ago in Europe.

According to Daly, although CT and MR modalities have been used intermittently for the past two decades “as a kind of one-off” for identifying a body or locating foreign objects, the University of Bern in Switzerland was the first to undertake a systematic study of CT forensics.

The driving force behind these formalized virtual autopsy techniques was Michael Thali, MD, now the managing director for the University of Bern’s Institute of Forensic Medicine. Thali’s work demonstrated that an interdisciplinary approach among radiology and forensics experts could create a flourishing virtual autopsy program.

These systems laid the groundwork for Daly’s own partnership with David Fowler, MD, the chief medical examiner for the state of Maryland. Daly says Fowler’s “enthusiastic, progressive work” made him believe he could bring stateside the forensic radiology begun in Bern. It also didn’t hurt that Fowler’s office is located in Baltimore, near the UM campus where Daly works.

Together, they developed a pilot study of 20 cases that compared the results of virtual autopsy conducted with CT or MR scans with conventional autopsy methods.

“Our initial work so far has been to apply CT imaging in the setting of blunt accidental trauma in the investigation of deaths,” Daly says. “We only started in December 2006, but in that space of time, we’ve done approximately 55 studies, most of which are CT total-body scans.”

Tech Specs

Typically, Daly scans the entire body with a 40-slice scanner at 1.0 mm sections, which are then reconstructed at 0.5 mm and overlapped to improve the reconstruction appearance. In an average scan, Daly gathers 3,000 to 4,000 images, which are stored on a server supplied by San Mateo, Calif.-based TeraRecon for as long as a month. The images are then reconstructed using volume-rendered techniques, such as multiplanar reconstructions of the spine, torso, and other regions.

“We can do from the top of the head through the thighs and then scan the lower limbs separately – you can’t do them all in one go unless it’s a child,” he says.

Of course, unlike with typical CT patients, “breathing is not an issue.”

According to Daly, CT is most useful for analyzing major blunt force trauma injuries, such as those sustained by passengers killed in serious car crashes, by penetrating wounds, or by other forms of accidental death. In such situations, he claims 3-D reconstruction produces results that are equally as useful as those turned up by autopsy. In cases of wrongful death, homicide or deaths of unknown causes, the law still requires autopsy for the sake of gathering evidence.

Even then, Daly says, CT can accelerate the effectiveness of traditional autopsy. “Autopsy is mandatory in gunshot wound deaths, for example,” Daly says, “but CT can help speed up that process for things like locating ballistic fragments.”

In fact, Daly’s team was able to locate the same number of major ballistic fragments recovered by conventional autopsy in his pilot study. Overall, Daly’s studies demonstrate that the evidence-gathering performance of virtual autopsy techniques is widely comparable to that of conventional methods. For instance, in 19 of the 20 cases, his results matched the medical examiner’s findings. Additionally, another benefit of CT scans is the fact they’re noninvasive and, therefore, do not destroy evidence.

CT saved time, as well, conducting and interpreting full-body scans in half an hour. Considering that 4,000 full autopsies were conducted in the state of Maryland in 2007, virtual techniques could realize a considerable cost savings over surgical autopsies – provided, of course, that radiologists are available to read and interpret them, and that dedicated scanning equipment is available for that purpose.

Expanded Applications

As Daly acknowledges, the program is still growing, and he hasn’t had the opportunity to truly broaden its scope. For now, he’s had to operate during hospital downtime, and that limits his access to the machines. Obviously, there are concerns about wheeling dead bodies into the hospital imaging facilities during normal hours.

“Our research, to some extent, has been limited by scan time and access in the hospital,” Daly says. “But even though we’ve not managed to scan as many bodies as we’d like, it only takes about five to 10 minutes for a typical, full-body scan.”

In addition to CT imaging, Daly has also made use of MRI technology in his conduct of virtual autopsies. MR is more sensitive for subtle injuries, such as damage done to soft tissue, brain injuries, and microfractures. The size of the equipment limits its use, however, to scanning individual organs or small children killed in cases of suspected non-accidental injury.

“The only time you can do an entire body scan with an MRI is if you’re dealing with a young child,” says Daly. “They take a long time, so if we’re doing an MRI, we would only do that for a small infant.”

In 2007, Daly and his team were awarded a $292,000 grant from the National Institute of Justice to study potential victims of elder abuse. They will evaluate 80 cases in two years to see whether they can detect instances of wrongful death and abuse of the elderly using CT and MRI, instead of surgical autopsy.

“Nobody’s quite sure how prevalent this type of crime is,” says Daly, “but this might be a good use of CT, especially for investigating situations where people die in residential care and assisted-living facilities.”

Another potential application of virtual autopsy that Daly anticipates is forensic dental radiology. Dentistry is a normal component of traditional forensic analysis, but it’s a painstaking and delicate procedure that requires hundreds of incisions to accomplish. The same jaw force that is required to create a bitewing X-ray may be impossible to coax from bodies damaged by fire, chemicals or decomposition, Daly says.

“One of the good things about the CT scan is that you can avoid dental X-rays,” he says. “Getting access to the jaw and teeth of a burned or decomposed body can be very difficult. Doing CT can avoid all the major, surgical processes involved in accessing the mouth in such cases.”

Virtual autopsy also bears the added benefit of being culturally and emotionally sensitive to the families and survivors of victims analyzed by the technique. Several religious and cultural groups, such as Muslims, Orthodox Jews, and American Indians, are quite opposed to autopsy for its destruction to the body, Daly says.

Although the Office of the Chief Medical Examiner is legally allowed to determine whether a conventional autopsy is necessary in every case, virtual autopsy could present a more compassionate alternative that provides comparable technical results.

“Families dealing with the trauma of the sudden death of a loved one have a difficult enough thing to deal with,” says Daly. “The thought of an autopsy is an additional stress that I think many of them would prefer to do without. Once this technique becomes more widely accepted, it would be an option that we would like to be in a position to offer,” he says.

— Matthew N. Skoufalos is a New Jersey-based freelance writer. Questions and comments can be directed to editorial@rt-image.com.