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Postmortem imaging and virtual autopsy

  • Method

CT and MRI of the body, before or instead of the autopsy, show fractures, gas, projectiles and bleeding, but do not replace the autopsy in a suspicious death.

Updated

What it is

Postmortem imaging uses radiology on the dead body: plain X-rays, CT (PMCT), CT with injected contrast to show the vessels (PMCT angiography), MRI (PMMR) and 3D surface scanning. The term 'virtual autopsy' has raised the expectation that a scan can replace the dissection, but the UN Minnesota Protocol says that is still far from true: imaging adds information and does not replace the autopsy in a potentially unlawful death. Its strengths are a fast overview of the whole body, fractures in places the autopsy rarely opens, gas, radiopaque foreign bodies and projectiles, a permanent digital record that others can review, and triage in disasters. Its weaknesses are poor soft-tissue and vessel detail without contrast, no colour and no small skin injuries, and the fact that samples for toxicology, histology and microbiology still require access to the body.

Accuracy and limits

  • In trauma, a systematic review found PMCT agreed with autopsy on the cause of death in 46–100 % of cases and detected 53–100 % of injuries.
  • The same review found injuries on PMCT that the autopsy had missed, so the two are complementary.
  • PMCT alone cannot confirm a cardiac cause of sudden death: it only shows coronary calcification.
  • Gas starts forming within hours of death, so its origin on imaging is hard to interpret.
  • Costly equipment, not widely available; sensitivity and specificity compared with autopsy are not fully studied.

What it is based on

  • X-rays pass through the body in a CT scanner and build cross-sectional images; dense structures (bone, metal) stand out.
  • MRI uses magnetic fields and shows soft tissues better; metal objects are a danger in the scanner.
  • In angiography, contrast is pumped into the vessels through a cannula to show leaks and blockages.
  • Images are stored digitally and can be reviewed by another expert or shown in court as 3D reconstructions.

How it is applied

  1. Scan the body in its bag, before undressing, when the case allows it.
  2. Read the images with a radiologist trained in postmortem changes, before the autopsy starts.
  3. Use the findings to guide the autopsy: where the projectile is, which fractures to expose, where gas lies.
  4. Take samples for microbiology and toxicology before injecting contrast, which can spoil them.
  5. Correlate each imaging finding with the autopsy and state which method showed it.
  6. If the authority decides on no autopsy, document the reasons and the limits of the conclusions.

Next step: what to do and document

  • In a gunshot death, request imaging before the autopsy to locate projectiles and fragments.
  • In child deaths, consider skeletal imaging or CT to look for old and new fractures.
  • Record in the report which imaging was done, when, by whom it was read and what it added.
  • Keep the images as part of the case file so that another expert can review them.
  • Do not issue a cause of death in a violent or suspicious death based on imaging alone.

Common mistakes

  • Reading decomposition gas as air embolism.
  • Reading postmortem clots or lividity in the lungs as disease.
  • Assuming a normal scan rules out an injury: small bruises, abrasions and many soft-tissue lesions are not seen.
  • Injecting contrast before taking samples for microbiology or toxicology.

Test yourself

Think of the answer, then tap the question to see it.

Can postmortem CT replace the autopsy in a potentially unlawful death?

No. According to the Minnesota Protocol it supplements the autopsy; samples and naked-eye findings still need the dissection.

Which imaging method is best for the source of internal bleeding and the coronary arteries?

Postmortem CT angiography, which injects contrast into the vessels.

Which postmortem imaging method is preferred for fetuses and young children?

MRI, because of its soft-tissue detail.

Which two things does postmortem CT not show well?

Small skin injuries and colour (bruises, abrasions) and the detail of soft tissues and vessels without contrast; it also cannot give toxicology or histology.

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Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.

Sources: Modern post-mortem imaging: an update on recent developments (Forensic Sciences Research (Grabherr S et al.), 2017); The value of postmortem computed tomography as an alternative for autopsy in trauma victims: a systematic review (European Radiology (Scholing M et al.), 2009); The Minnesota Protocol on the Investigation of Potentially Unlawful Death (2016) (Office of the United Nations High Commissioner for Human Rights, 2017).

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