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2 Alien objects exact location can be determined by DVR. Localization of a knife in a suicide (Fig. 2A) and in a murder case (Fig. 2B).

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Virtual Autopsyin Forensic MedicineThe methodology of autopsy has not undergone any major transformationsince the 19th century. But new radiological imaging methods such asmulti detector computed tomography (MDCT) and magnetic resonanceimaging (MRI) have the potential to become the main diagnostic toolsin forensic pathology.

By Prof. Anders Persson, MD, PhD

Center for Medical Image Science and Visualization (CMIV), Department of Radiology,

Linköping University Hospital, Linköping, Sweden

In forensic cases, the autopsy can pro-vide vital information in criminal investi-gations. A recent addition to routineautopsy workflow is CT postmortem 3Dimaging also known as Virtual Autopsy(VA). Excellent results are obtained usingMDCT, DSCT or MRI data from scans ofcadavers with direct volume rendering(DVR) 3D techniques1. The foundation of

VA development is the modern imaging

modalities that can generate large, high-quality data sets with sub-millimeterprecision. Interactive visualization ofthese 3D data sets can provide valuableinsight and enables non-invasive diag-nostic procedures.Several studies have shown the great po-tential of VA in forensic investigations 2–5.There are many reasons for increasing

interest in VA, for instance, they are time

saving and can complement standardautopsies enabling broader and moresystematic examinations. With VA, thebody remains intact, avoiding objectionsby family members or religious commu-nities and permitting additional analysisby other forensic pathologists on thesame body, in effect, second or thirddiagnoses/opinions. Images and results

of VA are understandable for jurors in

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1 Overview of the forensic autopsy procedure at CMIV. Virtual autopsy activities, shownin red, are added to the traditional workflow and enable an iterative approach. This gives theinvestigators time to complete the crime scene investigation before the physical autopsy.The procedure is based on a continuous interaction between the forensic pathologist, theradiologist, and the police.

3 Small metal fragments in a burned victim (blue color, Fig. 3A). Bul let in the neck region (arrow, Fig. 3B), shot through the oral cavity.

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criminal cases. Furthermore infectionsthat pose serious health risks for coro-ners, pathologists, and medical examin-ers can be avoided. And finally VArecords can easily and conveniently be

stored indefinitely.

The Virtual Autopsy Procedure

Autopsy procedures at the Center forMedical Image Science and Visualization(CMIV) in Sweden have been developedin collaboration with the Swedish Na-tional Board of Forensic Medicine. Theseprocedures are now routinely used forforensic examinations and have beenapplied in over 200 (mostly murder) cas-es. The research and development has

focused on the efficient workflow forpost-mortem CT and on developing soft-ware that can visualize full-body data-sets that could previously be viewedonly in separate parts with limited inter-activity 8.A SOMATOM® Sensation 16-slice con-figuration was initially used. Since Sep-tember 2006 a Dual Source CT scanner(SOMATOM® Definition) has been inservice with even better results.The workflow of the forensic procedureat CMIV is summarized in Fig. 1. The

traditional autopsy is supplemented by

adding the VA information shown in red.In most cases, the forensic pathologistcomes to the crime scene and overseesthe handling of the cadaver, which isplaced in a sealed body bag before being

transported to the forensic departmentand put into cold storage. The followingmorning, a full-body DSCT scan is per-formed in a few seconds. The radiologistand the forensic pathologist quicklyobtain a clear survey of the entire bodyand can use volume rendering transferfunctions (TF) to select aspects of thebody, such as the skeleton to localizefractures. The full-body procedure per-

mits fast localization of foreign objectssuch as metal fragments or bullets (Figs.2A–2B, 3A–3B). This can provide essen-tial information in the early part of thepolice investigation. Another important

aspect is the high resolution of the datathat allows details, such as dental infor-mation to be extracted for identificationpurposes. Another important feature isthat the captured DSCT data are digitallystored, which enables the information tobe re-examined as often as necessary.Frequently findings during the physicalautopsy lead to new questions that theVA can answer 9–14. Moreover, in crime

A 3B

Police Radiology Forensics

Crime sceneinvestigation

DSCT DVRvisualization

Interpretation Conventionalautopsy


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4 An Ex-vivo DSCT angiography of the heart with DVR can give an excellent anatomic visualization of the coronary arteries. Vascular patholo-gies such as calcification, stenosis and soft plaques can be detected. In this case iodine contrast has been injected through plastic tubes insertedinto the coronary arteries. Vessel wall plaque can be visualized with Dual Energy imaging.

scene investigations, new findings mayrequire other hypotheses to be scruti-nized by postmortem imaging. As men-tioned, VA is currently used as a compli-

ment to the standard autopsy proce-dure. The time needed for the DSCT scanand visualization session is short in com-parison to the physical autopsy and canmake the autopsy more efficient be-cause the pathologist has prior knowl-edge of the case before conducting thestandard autopsy. That the cadaver re-mains in a sealed body bag throughoutthe VA procedure also preserves techni-cal evidence, such as fibers and bodyfluids, which in forensic cases are ofgreat importance.

The use of DualEnergy CT for VA.

Dual Energy CT (DECT) with two X-ray

sources running simultaneously atdifferent energy levels, can acquire twodata sets showing different attenuationlevels, thereby obtaining additional in-formation about the elementary chemicalcomposition of the scanned material.Color can then be assigned according tothe value differences between 80 kV and140 kV. Such a color-mapped, dual energyimage can differentiate, for example,between calcifications and Iodine con-trast (Fig. 4). This technique can beused, for instance, for direct subtractionof bone from the CT raw data – withoutpost processing – to better visualizeblood clots in vessels and possible bleed-

ings in soft tissue 15, and to facilitateclassification of different tissue typessuch as tendons and cartilage. DEmakes CT an even more effective VA

tool (Figs. 5–6)15

.

The future forvirtual autopsies?To improve the forensic value of VirtualAutopsy (VA) with CT, a VA workstationneeds to be implemented. Visualizationtools to increase quality and efficiencyof the virtual autopsy procedures needto be developed that specifically addressforensic questions. And designated pro-tocols for the main forensic case catego-ries should be established.Data analysis research includes the im-plementation of computer aided diag-


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References

1 Donchin Y, et al., Journal of Trauma, 37(4):

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2 Ros P. R, et al., Magnetic Resonance Imaging,

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3 Thali M, et al., The American Journal of Forensic

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4 Thali M, et al., Journal of Forensic Sciences,

48:1336–1342, 2003.

5 Thali M, et al., Journal of Forensic Sciences,

48:386–403, 2003.

6 Jackowski C, et al., J Forensic Sci. 2005;50(5):5

5 Dual Energyimages. Hemosid-erin is visualized inred and bleedingcan be seen in theright pleural cavityand to the right ofaorta (arrows).

6 A child shotwith a handgun.Bullet in the neck

region (arrow)(Fig. 6A). The bul-let path visualizedwith Dual Energyimaging (Fig. 6B).

systems around the world must acceptthe admissibility of imaging evidence.And as a new field, postmortem radio-logy will require special training and

knowledge. Radiologists are trained tointerpret images of living patients, butthe dead often look different. For exam-ple, severe trauma or the effects ofdecomposition can displace organs.Understanding these differences will re-quire knowledge and expertise that doesnot exist on a widespread basis today.Invasive autopsies will remain the normfor at least the next few years. But, asknowledge and acceptance increase,traditional autopsy can gradually be re-placed by a non-invasive virtual autopsy,and, when necessary, minimum invasiveimage-guided tissue sampling can betaken. Postmortem VA has the potentialto gain high acceptance in the popula-tion as well as in professional circles,making possible high levels of qualitycontrol in forensic medicine.

7 Jackowski C, et al., J Forensic Sci. 2008, in press.

8 Ljung P, et al., 2006 IEEE T VCG , Proceedings

Visualization 2006, Baltimore.

9 Sylvan E, Master’s Thesis, Linköping University

2005: LiU-IMT-EX--05/410).

10 Oliver W. R, et al., Journal of Forensic Sciences,

40:321–324, 1995.

11 Etlik Ö, et al., European Journal of General

Medicine, Vol. 1, No. 4, 2004, pp. 48-52

12 Jackowski C. Thesis, Institute of Forensic Medi-

cine. O.-v.-G.-University of Magdeburg. 2003.

13 Jackowski C, et al., Forensic Sci Int. 2005 Apr 20;

149(1):11–23.

14 Kerner T, et al., Resuscitation 2003; 56(1):

111–115.

15 Engström E. Master Thesis Project Linköping

University, Sweden 2007.

nostic tools that can, once applied onthe post mortem volume data, help tosearch for relevant forensic findings,characterize them and deliver generalinformation of the deceased individualsuch as body height, weight, sex, majorinjuries, foreign bodies (e.g. projectiles)and likely causes of death in an auto-matically generated, preliminary writtenvirtual autopsy protocol.This would allow for virtual autopsies to

be performed in large numbers withina reasonable time frame to handle inci-dents such as the Tsunami catastrophein Asia 2004, where no autopsies wereperformed at all.For a new era of digital autopsies to trulyemerge, many social, legal, medical andtechnical areas must work in unison.Medical professionals and legal authori-ties must determine standard protocolsfor scanning and storing data. Legal

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virtual autopsy in forensic medicine-00085892

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