According to a study published Online First in The Lancet, two thirds of deaths referred to the coroner can be identified by post-mortem imaging. The study also showed that CT is more accurate than MRI for establishing the cause of death in adults, although common causes of sudden death, such as coronary artery disease are frequently missed on both CT and MRI.
Professor Ian S D Roberts, of the Department of Cellular Pathology at the John Radcliffe Hospital in Oxford, UK, and his team say that unless these weaknesses are addressed, mortality statistics would contain systematic errors should conventional autopsy be replaced with imaging.
In the past century traditional autopsy has barely changed. Bodies undergo external examination and evisceration, and if required, dissection of the major organs with identification of macroscopic pathologies and injuries as well as histopathology.
Concerns have been raised in the UK over the large number of performed autopsies, i.e. in 22% of deaths, and their adequacy.
The public, in particular communities of certain faiths, demand for an alternative to invasive autopsy, and although non-invasive imaging has the potential to address this need, its accuracy is unknown.
Professor Roberts and his team decided to evaluate the accuracy of post-mortem CT and MRI versus a full autopsy in a large series of adult deaths.
They evaluated 182 unselected cases referred to the coroner and performed CT and MRI scans prior to full invasive autopsy. Each case was reported independently, with radiologists providing a cause of death for each imaging modality to support the diagnosis, and to evaluate whether a full autopsy would be required if this was a routine service.
They discovered that in identifying the cause of death the overall largest discrepancy rates between radiology compared with autopsy consisted of 43% for MRI, 32% for CT, and 30% for the consensus radiology (CT + MRI) report, which was 10% lower for CT than for MRI. The biggest discrepancy occurred when the radiologist and pathologist reported a completely different type of pathology or organ system involved, such as myocardial infarction instead of pulmonary embolism.
According to radiologists, an autopsy was unnecessary in 34% of cases for CT as well as in both 48% of cases for MRI- and consensus-reports. When these cases were compared with autopsy, the major discrepancies occurred in 16% of cases for CT, 21% cases for MRI and 16% in consensus-reports, which was substantially less in those cases where radiologists showed less confidence regarding the cause of death.
The researchers discovered that the most prevalent imaging errors in identifying cause of death amongst all 182 cases consisted of 27 cases of ischemic heart disease, which were either missed or over attributed, in 11 cases of pulmonary embolism as well as in 13 cases of pneumonia and 16 cases of intra-abdominal lesions.
According to the authors:
“When radiologists are confident that the cause of death on imaging is definite, the discrepancy rate between the radiological and autopsy diagnoses is lower and might be acceptable from a medicolegal point of view.
The radiologists’ ability to accurately identify cases for which their diagnosis is correct is essential for the safe introduction of a minimally invasive autopsy service… If used as a pre-autopsy screen, imaging might avoid unnecessary autopsies (e.g., for ruptured aortic aneurysm), identify lesions difficult to diagnose by dissection, and help to guide dissection by identification of pathologies needing further investigation. Therefore, imaging could reduce the number of invasive autopsies at the same time as improving their quality.”
They continue saying:
“Practical and clinical governance considerations remain. Where will imaging be done? If clinical facilities are used, providers should ensure that services for living patients are not disrupted. Service providers will need training and assessment in the interpretation of post-mortem imaging. Cost implications are also a concern; MRI in particular is more expensive than is traditional autopsy.
Further development of postmortem imaging is needed and this development must be based on careful consideration of comparisons between radiology and autopsy.”
Professor James Underwood, University of Sheffield, UK, says in a linked comment:
“Post-mortem imaging cannot yet be regarded as a universal substitute for autopsy; it is one of several methods available for determining the cause of death. In some cases, post-mortem imaging might be better than autopsy; in others, imaging augments the autopsy.
Whichever method is chosen, all death investigations should begin with a thorough review of the deceased’s clinical history and meticulous external examination of the body. When indicated, percutaneous needle sampling for histology of internal organs could be sufficient.”
He concludes:
“However, dependent on circumstances, the cause of death is likely to be established most comprehensively and reliably by autopsy with histology, or in carefully selected cases by post-mortem imaging, or by both techniques.”
Written by Petra Rattue