Postmortem CT in Trauma Rathachai Kaewlai, MD

BG Gil Brogdon, MD

It is believed that forensic scientists in other disciplines would find radiologists in their area interested in cooperative efforts

Sharing of interdisciplinary skills and knowledge would

•  Improve the economy and effectiveness of investigative efforts

•  Prevent some false starts and/or reinventions of well-worn wheels, and most important,

•  Expand scientific horizons

Gil Brogdon, MD Father of Forensic Radiology

1929-2014

Outline

Postmortem imaging techniques

Role of PMCT in trauma Normal PMCT findings Traumatic pathologies on PMCT

Current status at Ramathibodi Q & A

Death Investigation

Situation peaceful No injuries

Medical history and ID cleared

Liberation for funeral

Death Investigation

Situation suspicious? Possible malpractice?

Legal inspection for MOD, TOD and triage If cannot answer

Autopsy

(usually head, thorax, abdomen)

Postmortem imaging Radiography CT CT angiography MRI

MOD = mode of death, TOD = time of death

“Virtopsy”

Virtual autopsy

Began in Germany, now settled in Switzerland What it covers: PMCT, PMCTA, PMMR

Biopsy Surface scanning Virtual reconstruction of trauma events

Virtopsy.com

PM Imaging: Filling the Void of Traditional Autopsy Traditional autopsy = reference standard

But Invasive Certain body parts difficult to dissect

Require permission from relatives of trauma victims Religious issue

Focusing on Trauma and PMCT

Very common Every 5s, a person in the world dies from trauma

Major cause of death worldwide 2nd in Thailand 1st in age group of 1-45 years in developing countries

Proven usefulness of PMCT New technology allows fast imaging in seconds 3D reconstruction for visualization

PMCT to Answer ���Key Forensic Questions Identity

Time of death Injuries: Self inflicted or 3rd party, priority, vitality, survival time

Type, severity, instrument, direction Concomitant injuries Reconstruction of events

PMCT: Advantages

To physicians Analysis of organs in situ Info added to autopsy

Less time consuming in certain body parts than autopsy (neck, spine, pelvis)

Stored images for years Trauma care evaluation Education Research

To victims’ relatives Less invasive Less rejection No religious issue

PMCT: Techniques

Coverage

Head/neck Body to knees or lower

No IV contrast

Arms on side High dose for image quality 2D reformations

3D imaging

PMCT: Supporting Evidence

Systematic review in Forensic Science International

Jalalzadeh H, et al. (2015) from The Netherlands 26 studies, 563 trauma victims

“PMCT demonstrated moderate to high-grade injuries and COD accurately”

“PMCT more sensitive than conventional autopsy in detecting skeletal injuries”

Normal PM Changes Seen on CT

Livor mortis

Rigor mortis Algor mortis Decomposition

Putrefaction

Livor Mortis

Seen in all fluid compartments, internal organs, soft tissues of body

Increased attenuation in subcutaneous tissues, lungs, and solid organs with AP gradient in dependent part

Livor Mortis

Separation of components of blood in vascular compartment “Hematocrit effect”

Postmortem Decomposition

Dependent on multiple variables

Early in warmer temperatures and humid conditions Imaging “lag time” = a few hours after death Obvious within 24-48 hours

“Severe decomposition” images from Levy AD et al. Radiology 2007

Autolysis of Brain Parenchyma

Loss of gray-white differentiation (within 6 hrs)

Effacement of sulci

Normal

Putrefaction

Accumulation of air within brain, subQ, internal organs (such as liver, pancreas, kidneys), vessels (mesenteric/portal system, aorta, celiac trunk, SMA)

Putrefactive Hepatic Gas

Most common in portal syst

As early as 4-7 hr after death First seen in nondependent

anterior liver (LL), then diffusely within 24 hours

In hepatic veins, hepatic arteries and biliary tree, air is usually due to trauma or other pathologies

Putrefactive ���Pneumatosis Intestinalis

Intramural bowel wall air –nonspecific sign should not be mistaken for bowel injury

Pathologies: Skeleton

PMCT detects more skeletal injuries than autopsy

Especially better than autopsy for AIS 1-3 injuries

PMCT good for areas not easily accessible for dissection (facial skeleton, pelvis)

Soft Tissues

Hematomas often overlook with PMCT

Autopsy superior to PMCT For soft tissue and vascular injuries Even with AIS 3+ injuries

Exception is abnormal gas collections PMCT far better than autopsy even with under water technique

Calvarial Fractures

PMCT ~ autopsy

Facial and Skull Base Fractures

Facial fractures – PMCT better or equal to autopsy

Skull base fractures – autopsy better

Brain Hemorrhages

In general, brain lesions better with autopsy

Brain hemorrhages – PMCT ~ autopsy But small ones can be missed on PMCT

IVH – PMCT better

SAH, IVH, subgaleal hematomas

PMCT Explanation on Cause of Death in the Brain

Decebration

Traumatic external brain herniation

Crush fractures of skulls Extensive IVH Cerebral venous gas

emboli 2/2 open-skull fractures

External brain herniation

Cerebral Venous Air Embolism

Air in cerebral ven sinuses

Air in supracardiac neck veins Air in right side of heart, PA

and branches

Retrograde air filling in IVC, hepatic veins, renal veins

Images from Panda A et al. Curr Probl Diagnost Radiol 2015

Traumatic Intraocular Hemorrhage

May be a/w orbital and skull base fractures

Potentially missed on autopsy

Right intraocular hemorrhage

Hemothorax

PMCT better, small fluid easily detected with PMCT

Including blood in mediastinum/pericardium Mediastinal shift better with PMCT

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Pneumothorax

Gas-related injuries difficult to detect with autopsy

PMCT better, including gas in mediastinum/pericardium

Mediastinal shift better with PMCT

Tension can be a cause of death and lead to pneumorachis and pneumocephalus, subsequently causing death

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Lung Lesions (in general)

Autopsy better

PMCT problem Hypostasis (normal PM change) Trauma: contusions, lacerations

Non-trauma: aspiration, infective pneumonia, edema Need correlation with time and mechanism of injury

Pulmonary Injuries

Large lacerations may be COD

Pulmonary alveolo-venous fistula formation Systemic arterial gas emboli

Open chest wall injury + lacerations +

Aspiration

Fluid in airways (*), esophagus and stomach

Opacities in dependent portions of lung (*)

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Heart and Mediastinum Lesions

In general, autopsy better

Only large lesions can be seen on PMCT Pneumopericardium – PMCT better Hemopericardium – PMCT ~ autopsy

Vanishing Aorta Sign

Specific PMCT sign for exsanguination (of any origin) as a cause of death

Small and indiscernible aorta

Images from Panda A et al. Curr Probl Diagnost Radiol 2015

Cardiac Clues

Giving clues to nontraumatic cardiac cause of death even in patients with history of trauma and without other obvious signs of injury

Cardiac hypertrophy Atherosclerotic aortic and

coronary calcifications Valvular calcifications

Coronary calcification

Abdomen/pelvis Organ Injuries

Autopsy better than PMCT

Only high-grade injuries may be found at PMCT Poor detection for spleen, kidney injuries

Retroperitoneal hemorrhage

C-spine – PMCT better or ~ autopsy

Dislocations – PMCT ~ autopsy T-spine – PMCT ~ autopsy L-spine – PMCT better or ~ autopsy

Spine Fracture/Dislocation

Spine fracture/dislocation

Pneumorachis

Potential cause of cord compression leading to death

Pneumorachis

Strangulation

Pneumomediastinum and cervical emphysema with abrupt cutoff at level of strangulation

Suggestive of antemortem hanging

Hyoid bone fractures Autopsy better

Cervical soft tissue injuries

Gunshot Wound

Delineate number and location of entry/exit wounds, position, size/number of pellets, trajectory of bullets, internal injuries, likely cause of death

Cause of Death

Few PMCT studies investigated cause of trauma deaths

Exsanguination Central respiratory paralysis Hemopericardium

Concurrent gas embolisms Reports of limited no. of cases – most COD given by

PMCT were correct

Pitfalls

Common in soft tissues, heart, mediastinum, vessels and abdomen (missed diagnosis)

Unable to differentiate causes of pulmonary opacities

Setting up PMCT: Prerequisites

Curiosity

Cooperation between imaging and forensic teams Both physicians and non-physicians Role understanding

Readiness to learn Availability of scanner A little knowledge on forensic pathology, imaging

technique, interpretation and limitations

Summary

PMCT in trauma can detect wide spectrum of injuries

Most useful in detecting craniofacial, cerebral, thoracic and osseous injuries

Complementary to autopsy Can obviate need for autopsy in specific situations Limitations include inability to obtain toxologic samples,

hypothermia/burn as COD, pulmonary and fat emboli, myocardial infarctions, other natural COD