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TECHNOLOGY advances not only through new inventions, but also by the
imaginative application of old ones. And one of the most ancient forms of
scientific investigation, the post-mortem autopsy, may be ripe for just such a
technological upgrade. According to a paper in this week's Lancet, published by
Ian Roberts of the John Radcliffe Hospital, in Oxford, it may soon be time to
put away the scalpel and the retractor clamp, and to replace them with the body
scanner.
The study of death is never a cheerful topic, but it has gone through a
particularly gloomy patch over the past few decades. A recent tally by America's
Centres for Disease Control and Prevention showed that in 2007 only 8.5% of
deaths in America were investigated by autopsy. In 1972 that figure was 19.3%.
Britain's coroners are more active, but perhaps not more accurate. Twenty-two
percent of deaths in the United Kingdom lead to an autopsy. According to a
government review, however, one in four is of miserable quality. The upshot in
both cases is not just that the cause of individual deaths may be misascribed.
More seriously, data about the processes of disease are lost, and those diseases
are thus not as well understood as they might have been. Squeamish relatives of
the deceased, too, often do not like the idea of bodies being cut up at the
behest of coroners. Britain's health department therefore commissioned Dr
Roberts to study whether scanning dead bodies in the way that is routine for
living ones would help. His conclusion is that it would.
Rather than slicing the body with a knife, scanning slices them with
radiation. Computerised tomography (CT) uses X-rays to collect information from
many angles, and a lot of processing power to convert that information into
cross-sectional images of a body's inner tissues. In forensic cases CT scans are
often used to spot fractures and haemorrhages. Dr Roberts found them adept at
noticing diseased arteries, as well. The other widespread scanning technique,
magnetic-resonance imaging (MRI), uses radio waves and is best suited for
exploring the detail of soft tissues.
Though both of these technologies have been around for a long time, they
have had only limited use in autopsies. America's authorities conduct CT scans
of dead soldiers—but such scans are employed to augment traditional post
mortems, not replace them. Some coroners in England, spurred on by the religious
objections of Jews and Muslims, do allow scans rather than conventional
autopsies in certain cases. But the accuracy of these scans is unknown. Dr
Roberts is the first to provide data on whether scanning might replace
conventional methods.
He and his colleagues examined 182 bodies in Manchester and Oxford.
Radiologists studied CT and MRI scans of these bodies, made diagnoses based on
them, explained their confidence in these diagnoses, and judged whether the
scans might thus preclude the need for a full autopsy. Within 12 hours of each
scan, a pathologist then performed a conventional autopsy, so that Dr Roberts
could compare the new methods with the old.
The scans were far from perfect. The rate of discrepancy between the cause
of death, as determined by radiology and as determined by conventional autopsy,
was 32% for CT scans, 43% for MRI and 30% for a combination of CT and MRI. Most
troubling, the scans had difficulty showing heart disease, a common killer.
However, radiologists were good at identifying which diagnoses were sound and
which needed to be re-evaluated by a full autopsy. When they felt confident in
their diagnoses—which was the case for 34% of CT investigations and 42% of
MRIs—the discrepancy between the results from scanning and those from autopsies
was lower. For CT scans, it was just 16%.
That is still a significant gap, of course. But not all of it is caused
because traditional methods are better. For one body, for example, scanning
revealed a lethal stroke that dissection missed.All this suggests that scans
might play a useful role in determining causes of death. When a radiologist is
confident in the diagnosis from a scan, a traditional autopsy might be
unnecessary. When he is less confident, his scan could still be a useful guide
for the wielder of the knife.
Automating autopsies by using scanners might also make them cheaper, by
speeding the process up. And it could be done with otherwise-redundant machines
that have been replaced for use on live patients with modern devices which give
off less radiation. That would get rid of the need to buy new kit to cope with
the extra demand for scans. A thorough study of the costs of both approaches
would be needed, of course, and traditional autopsies are unlikely to disappear
completely. But for some deaths, a scan will likely prove better than a
scalpel.