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Sunday, April 1, 2012

Autopsy without the knife

Autopsies are an unpleasant necessity.  No one likes the thought of having his recently deceased loved one cut open. That's just one reason that Ian Roberts from John Radcliffe Hospital and his colleagues are testing the accuracy of using computed tomography (CT) and magnetic resonance imaging (MRI) scans in lieu of dissection. Unfortunately, it's not quite ready for prime time.

182 cadavers were subjected to both CT and MRI scans.  Radiologists, some generalists and some specialists in brain or cardiac imaging, evaluated each cadaver and gave their opinions as to the cause of death and whether they believed any further autopsy was necessary.  Each of the 182 bodies was then given a full autopsy.

How did the scans fare?  Not so well.  The mismatch between stated cause of death for autopsy and CT scan was 32%.  It was even worse for MRI, with a 43% discrepancy. Using both types of imaging brought the error rate down to 30%.  Of course, these included the cases that the radiologists thought required further autopsy, and thus may have had ambiguous scans.  How about situations when the radiologists were confident enough to say that no traditional autopsy was needed?  The error rate for those cases ranged from 16% to 21%.  I should point out that these figures are for the ‘major discrepancy’ rate.  In other words, at least a sixth of the time, a radiologist would attribute a death to the wrong internal organ. 

I suggest that if you really want to know how and why someone died, you should make sure he gets a full autopsy.  If that isn’t so important, imaging does have advantages.  Aside from being totally non-invasive (a plus for open-caskets), the scans can be saved for future study.