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The Virtues of the Virtual Autopsy
Hugh Pickens writes "Maryn McKenna writes in Scientific American that the standard autopsy is becoming increasingly rare for cost reasons, religious objections, and because autopsies reveal medical mistakes, making doctors and hospitals uncomfortable. Researchers in several countries have been exploring the possibility that medical imaging might substitute a 'virtual autopsy' for the more traditional variety. 'So few autopsies are being done now that many medical students get out of school never having seen one,' says Gregory Davis. 'And yet in medicine, autopsy is the most powerful quality-control technique that we have and the reason we know as much as we do about many diseases and injuries.' The process, dubbed 'virtopsy,' combines MRI and CT scanning with computer-aided 3-D reconstruction to prove causes of death for difficult cases, which included drownings, flaming car crashes, and severe injuries to the skull and face. Since 2004 the U.S. military has performed x-rays and CT scans on the bodies of every service member killed where the armed forces have exclusive jurisdiction — that is, not just on battlefields abroad but on U.S. bases as well. 'It allows us to identify any foreign bodies present, such as projectiles,' says Edward Mazuchowski. 'X-rays give you the edge detail of radio-opaque or metallic objects, so you can sort out what the object might be, and CT, because it is three-dimensional, shows you where the object is in the body.' A study conducted among intensive care unit patients in Germany compared diagnoses made before death with the results of both traditional and virtual autopsy in 47 patients and with only virtual autopsy in another 115 whose families refused standard autopsy. Virtual autopsies confirmed 88 percent of diagnoses made before death, not far behind the 93 percent rate for traditional postmortem exams. 'The findings so far are mixed,' says Elizabeth Burton of Johns Hopkins University. Virtual autopsy, she says, 'is better for examining trauma, for wartime injuries, for structural defects. But when you start getting into tumors, infections and chronic conditions, it's not as good, and I doubt it will ever be better.'"
...cost reasons, religious objections, and because autopsies reveal medical mistakes, making doctors and hospitals uncomfortable.
Say what? Does anyone else see that last reason list as completely asinine with regards to not doing an autopsy? Ok, maybe the religious one is a silly objection, but there's no need to go against the religious beliefs of the deceased/close family members, at least as long as foul play isn't a concern. But, because it might reveal the f*ck-ups of the quack that took your tonsils out? Yeah, I'm not getting the point of that one...
Deja Moo: The distinct feeling that you've heard this bull before.
No – it makes complete rational sense. You want other hospitals to do autopsies – you want other people to bear the expense, the time, the embarrassment of mistakes gone wrong (and the potential lawsuits) to do the basic research that will help you.
It is a classic (and I mean classic) of things not getting done because the positive externalities are not captured.
can anyone summarize?
Sure. If you substitute a CAT scan for a real autopsy it works just as well, except when it doesn't.
You are thinking of an MRI.
Potentially by a significant margin. In practice, most of the equipment is tuned to specific requirements of resolution, etc. Some flexibility is possible, for example, the use of mammography film/sensors for x-raying limbs for forensic purposes (usually child abuse cases). Mammography films/sensors have very low sensitivity but exceptional resolution and very high contrast; however, the full benefit cannot be obtained as a micro focus mammography x-ray source has insufficient energy to penetrate bone, so a conventional x-ray source with poorer focus must be used.
CT has greater scope for improving the images quality, because CT image noise limited by photon shot noise in order to keep doses down. With modern scanners, they typically scan at maximum resolution always, but can then resample the images to lower resolution if desired for viewing (usually to reduce noise, or in my hospital's case because their SAN contract means archiving the full resolution data is cost-prohibitive). The technologist instead of controlling scanner parameters directly, merely specifies the desired quantity of noise at a standard resolution.
From a medical perspective, this doesn't actually give much benefit in terms of diagnostic performance. From a practical perspective there are other issues as technologists are often barely trained. I once asked a CT technologist to scan a dry skull for use as an anatomical teaching tool, and asked them to crank up everything on the scanner to maximum; they couldn't do it even when I told them exactly what settings to change. As another example, I was looking at the functionality available on the scanner, which used a "tab page" control for the scan parameters and when I finished, I left the 2nd page visited rather than the first; I got my ass chewed out for that because the technologist couldn't work out what had happened to the scan settings, necessitating delaying an emergency scan and prompting an emergency support call to the scanner manufacturer.
autopsies are very expensive taking many hours of a pathologists time as well as extensive time of technical and assistant staff.
Quite right, it's not really clear who's on the hook to pay. In theory, the cost of autopsies are supposedly covered in the contracts hospitals have with government and private insurance, but often as a hazy "it's included" concept, often with no budget earmarks for the departments that would actually do the work, and no change in funds for increased (or decreased) use of autopsies.
But there are major religions which objections to autopsy as well, including Islam and Judaism, though as usual it seems to depend on the local imam/rabbi.
I'm sure they are out there, but I've never actually known a case of a physician objecting to an autopsy for fear of uncovering their errors. The egotistical among us I suspect feel they would likely be exonerated, and many (perhaps most others in these parts anyway, among my colleagues in the US Pacific Northwest) honestly would want to learn from their mistakes. Nevertheless, it's hard to figure out who funds them, and many families tend to feel it's a final act of violence. Still, it's hard for me to wrap my head around getting a more accurate, cost-effective answer from a CT scan than a old-fashioned postmortem.