New Page 0

ADVANCES IN FORENSIC MEDICINE – THE USE OF CT SCANNERS ON THE DECEASED

Sunday 9^th 11.55pm

CT scanning has become an integral part of the autopsy process at the Victorian Institute of Forensic Medicine. Although its role is evolving as pathologists become more comfortable with and knowledgeable about its abilities and deficiencies, it has led to a substantial cultural change in the conduct of death investigation. Increasingly publications from overseas groups have heralded the prospect of virtual autopsy i.e. the "scalpel-less" post mortem examination utilising sophisticated imaging and targeted percutaneous sampling of tissue. This is clearly an exciting prospect welcomed by those for whom the autopsy is an anathema and bureaucrats looking for strategies to overcome shortages in medical manpower. We at VIFM do not believe that CT or other more sophisticated imaging for that matter, will in the foreseeable future replace the autopsy rather it will remain an adjunct to it, used by pathologists in formulating reports on the cause of death, a process we would prefer to call CT or imaging assisted autopsy rather than virtual autopsy.

Dr Chris O'Donnell

Chris is a Clinical Radiologist who for the last 5 years has explored the use of advanced Radiological techniques in the forensic environment. In May 2005, a multidetector CT scanner was installed into the VIFM mortuary. Since that time over 5000 deceased persons have been examined. This is by far the largest experience of post mortem CT in the world. Chris’ major research interest is the use of CT to understand changes to the body that occur after death such as decomposition. This interest has spawned a new radiological specialty known locally as "Necro-Radiology"

OVERVIEW

Use Of The Ct Scanner In The Deceased

Dr Chris O’Donnell ‘Necroradiologist" VIFM Director of Radiology, Mornington Peninsula Health

Background

VIFM installed a CT scanner in the mortuary in 2005
Funding for scanner from Office of Emergency Services on basis it could be used to assist in identification of victims of mass disasters
All bodies/tissues referred to coroner in Victoria are scanned (unless physically impossible eg size, unusual posturing 2° rigor mortis)
Approx 4000 bodies per year – to date approx 6000 cases have been scanned

All data stored on a computer – scans can be accessed remotely
Not all CT’s reviewed by radiologist (workload) – pathologists have had some training in CT interpretation

Differences between ante mortem (AM) and post mortem (PM) CT’s

Significant differences exist – no existing data base indicating differences thus this data base prob largest in world
Can’t use oral or IV contrast
Evolving specialty of post mortem CT interpretation
Examples of differences

In PM, aorta looks flat vs round structure in AM

Gas appears in tissues 2° decomposition

Sand in tracheo-bronchial tree seen in drowning – not seen in life!

CT appearance of maggots

Extradural haematomas seen in incinerated bodies

Use of CT scanner at VIFM

Section 29 objection to autopsy – NOK can lodge an objection to autopsy – in this case, pathologist does and external examination and peruses medical notes, circumstances to see if cause of death can be determined. Pathologist can now examine CT scan which may add information.
Examples of obvious causes of death on CT scan

Aortic dissection, Ruptured AAA, Obstructed inguinal hernia

Additionally, may give clues as to suspicious findings in which case pathologist will indicate to coroner that autopsy is necessary

Eg subdural haematoma in body where otherwise nil suspicious external findings

Problems with PM CT’s

False negatives

Cannot diagnose AMI

Cannot differentiate antemortem PE from PM clot in pulmonary arteries

Small bowel may look normal on CT yet autopsy demonstrates infarcted bowel

False positives

PM lividity in the head gave appearance of subarachnoid haemorrhage

Utility of CT in cases where autopsy will be conducted

May assist in dilemma of organ retention

Eg brain is jelly-like and ideal method to section brain is to "fix" in formalin for a period of time, however cannot then be buried with body. CT scanning allows another method of examining brain tissue without having to retain brain

Planning autopsy
Assists where anatomy is complex
Identifies hazards such as sharps (IVC filter) & cavitating TB lesions (infectious hazard)
Acts as a permanent record which can be reviewed

Eg case where an incinerated body exhumed when info led to death being treated as suspicious – issue of whether a fracture on the skull occurred during or before exhumation – area could be reviewed on CT which demonstrated presence of fracture originally

Used in identification of bodies

Eg 2 bodies in plane crash – very disrupted, multiple bags of human tissue retrieved – bags were scanned to allow identification of organs// bones

Possible sexual assault case!

Elderly female living alone found deceased – family objected to autopsy but pathologist noted possible vaginal fb on external inspection. CT scan conducted – foreign body confirmed in vagina thus proceeded to autopsy. Found to have lid of soap dispenser bottle in vagina with chronic reactive inflammatory tissue – postulated pt had self-inserted during dementing process – not suspicious.

Notes by Dr Helen Parker