A study published Online First by the Lancet shows that post-mortem imaging can identify the cause of death in two thirds of cases referred to the coroner, and that CT is a more accurate imaging technique than MRI for providing a cause of death in adults. However, common causes of sudden death -- such as coronary artery disease -- are frequently missed on CT and MRI, and, unless these weaknesses are addressed, systematic errors in mortality statistics would result if imaging were to replace conventional autopsy. The Article is by Professor Ian S D Roberts, Department of Cellular Pathology, John Radcliffe Hospital, Oxford, UK, and colleagues.
Traditional autopsy has changed little in the past century, consisting of external examination and evisceration, dissection of the major organs with identification of macroscopic pathologies and injuries, and histopathology if needed. In the UK, concerns exist about the large number of autopsies done (22% of deaths), and their adequacy. There is public demand for an alternative to invasive autopsy, particularly from certain faith communities. Non-invasive imaging has potential to address this need, but its accuracy is unknown. In this study, Roberts and colleagues aimed to identify the accuracy of post-mortem CT and MRI compared with full autopsy in a large series of adult deaths.
The researchers assessed 182 unselected cases referred to the coroner. CT and MRI scans were performed prior to full invasive autopsy and each reported independently. Radiologists provided a cause of death for each imaging modality, an indication of confidence in their diagnosis and whether full autopsy would be necessary if this was a routine service. The overall major discrepancy rates between cause of death identified by radiology and autopsy were 32% for CT, 43% for MRI, and 30% for the consensus radiology (CT + MRI) report; 10% lower for CT than for MRI. A major discrepancy was one in which the cause of death provided by radiologist and pathologist reported a completely different type of pathology or organ system involved, for example myocardial infarction vs pulmonary embolism.
Radiologists indicated that autopsy was not needed in 34% of cases for CT, 48% of cases for MRI reports, and 48% of cases for consensus reports. Of these cases, the major discrepancy rates compared with autopsy were 16%, 21%, and 16%, respectively, significantly lower than for those cases in which the radiologists were less confident about cause of death. Among the 182 cases examined, the most common imaging errors in identification of cause of death were ischaemic heart disease (27 cases missed or overattributed), pulmonary embolism (11), pneumonia (13), and intra-abdominal lesions (16).
The authors say: "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 (eg, 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 add: "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."
In a linked Comment, Professor James Underwood, University of Sheffield, UK, says: "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.
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."
Professor Ian S D Roberts, Department of Cellular Pathology, John Radcliffe Hospital, Oxford, UK. T) 44-1865-222889 / 44-1865-220498 (secretary) E) ian.roberts@ouh.nhs.uk
Dr James Underwood University of Sheffield, UK. T) 44-7976-923399 E) jceu@shef.ac.uk
Journal
The Lancet