Imaging Findings in Blast Trauma on Post-Mortem CT
Post-mortem CT (PMCT) in blast trauma victims demonstrates a characteristic "peribronchovascular" pattern of lung injury with central ground-glass opacities and consolidation, along with superior detection of skeletal injuries compared to conventional autopsy, though it may miss some soft tissue and vascular injuries that require autopsy confirmation. 1, 2, 3
Primary Pulmonary Findings
Blast lung injury presents with distinctive imaging patterns on PMCT that differ from other thoracic trauma mechanisms:
- Central peribronchovascular distribution of ground-glass opacities and consolidation, historically described as "batwing" or "butterfly" pattern on radiography, but more accurately characterized as peribronchovascular on CT 3
- Ground-glass opacities appear as areas where lung interstitium and vasculature remain visible through the opacity, often with crescentic morphology 3
- Areas of consolidation that do not respect anatomic lobar boundaries, distinguishing blast injury from infectious processes 3
- Pulmonary contusions manifest as patchy, ill-defined, non-segmental consolidations that may show sub-pleural sparing 3
Skeletal Trauma Detection
PMCT demonstrates superior sensitivity compared to conventional autopsy for detecting bone injuries:
- Almost perfect concordance with autopsy for skull fractures, basal skull fractures, facial fractures, vertebral fractures, and pelvic fractures 4
- Detection of fractures in posterior body regions that are difficult to examine during standard autopsy, particularly important for reconstructing blast mechanism 2
- Hyoid bone fractures are reliably identified on PMCT 4
- Rib fractures and flail chest segments are clearly visualized, noting that flail chest occurs four times more frequently in combat casualties than civilian populations 3
Soft Tissue and Vascular Injuries
PMCT has important limitations in detecting certain injury types:
- Intracranial injuries, vascular wounds, and organ injuries show discordance with autopsy, with conventional autopsy detecting more findings than PMCT 4
- Pulmonary lacerations may not be visible immediately and can present 48-72 hours post-injury due to elastic recoil of surrounding parenchyma, appearing similar to contusions initially 3
- Thoracic and abdominal visceral injuries are better detected by conventional autopsy than PMCT 2
Gas and Air Detection
PMCT demonstrates superior sensitivity for detecting air in anatomical cavities:
- Free air detection in body cavities is more readily identified on PMCT compared to autopsy 4
- Pneumothorax and hemothorax are clearly visualized on PMCT 3
Technical Considerations for PMCT
Optimal imaging protocols for post-mortem blast trauma evaluation:
- Multidetector CT (MDCT) with multiplanar reconstructions (MPR) and volume rendering (VR) provides comprehensive assessment 2, 3
- Non-contrast imaging is standard for PMCT, as IV contrast administration is not feasible post-mortem 2, 4
- Whole-body scanning should be performed to capture the full extent of blast injuries 2
Critical Pitfalls to Avoid
Time-dependent changes and interpretation challenges:
- Difficulty differentiating antemortem from postmortem changes is a significant limitation of PMCT that requires correlation with autopsy findings 1
- Delayed appearance of pulmonary lacerations means initial PMCT may underestimate injury severity 3
- Presumed cause of death in trauma has been proven wrong by autopsy in approximately 30% of cases, emphasizing the complementary role of PMCT and autopsy 1
Cause of Death Determination
PMCT effectiveness varies by injury mechanism:
- Highly effective in determining lethal lesions in craniofacial trauma and gunshot wounds 4
- Complementary role with autopsy required for comprehensive assessment, particularly for soft tissue and vascular injuries 1, 2
- Useful for reducing unnecessary autopsies in cases where skeletal trauma clearly explains the cause of death 4