Eur Radiol (2008) 18: 273–282 DOI 10.1007/s00330-007-0737-4 FORENSIC MEDICINE Stephan A. Bolliger Virtual autopsy using imaging: bridging Michael J. Thali Steffen Ross radiologic and forensic sciences. A review Ursula Buck Silvio Naether of the Virtopsy and similar projects Peter Vock Abstract The transdisciplinary re- addition, is also well suited to the Received: 26 March 2007 Revised: 25 June 2007 search project Virtopsy is dedicated to examination of surviving victims of Accepted: 16 July 2007 implementing modern imaging tech- assault, especially choking, and helps Published online: 18 August 2007 niques into forensic medicine and visualise internal injuries not seen at # Springer-Verlag 2007 pathology in order to augment current external examination of the victim. examination techniques or even to Apart from the accuracy and three- offer alternative methods. Our dimensionality that conventional project relies on three pillars: three- documentations lack, these techniques dimensional (3D) surface scanning for allow for the re-examination of the . S. A. Bolliger (*) M. J. Thali the documentation of body surfaces, corpse and the crime scene even S. Ross . U. Buck . S. Naether Centre for Forensic Imaging and and both multislice computed tomog- decades later, after burial of the corpse Virtopsy, Institute of Forensic raphy (MSCT) and magnetic reso- and liberation of the crime scene. We Medicine, University of Bern, nance imaging (MRI) to visualise the believe that this virtual, non-invasive Buehlstrasse 20, internal body. Three-dimensional or minimally invasive approach will 3012 Bern, Switzerland e-mail: [email protected] surface scanning has delivered re- improve forensic medicine in the Tel.: +41-31-6318411 markable results in the past in the 3D near future. Fax: +41-31-6313833 documentation of patterned injuries and of objects of forensic interest as Keywords Forensic imaging . P. Vock well as whole crime scenes. Imaging Virtopsy . Computed tomography . Department for Diagnostic Radiology, . Inselspital, University of Bern, of the interior of corpses is performed Magnetic resonance imaging 3010 Bern, Switzerland using MSCT and/or MRI. MRI, in Surface scanning Introduction Vogel [4] have mentioned the usefulness of radiology in forensic medicine. Forensic science has experienced revolutionary changes in Although conventional X-rays have found their way into different fields, such as genetics, crime scene investigation daily forensic practice, newer, clinically established meth- methods and toxicology. Forensic pathology, by contrast, ods, such as CT and magnetic resonance imaging (MRI), still utilises the time-old, evidence-based methods intro- seem to lag behind in their forensic implementation. duced centuries ago; namely, the dissection of a corpse, and This conservative attitude towards new technologies is an oral description and written documentation of the surprising in a field in which prosecutors and defence findings obtained [1]; this has been augmented in the past lawyers are, depending on the case circumstances, often decades by photography. eager to test novel methods. With the advance of medical technologies such as Regardless of these obstacles, many different institutions computed tomography (CT) introduced by Hounsfield and have implemented CT in post-mortem forensic investiga- Cormack in the early 1970s, new possibilities became tions. For instance, a group from the Office of the Armed available for forensic pathologists. A first CT scan was Forces Medical Examiner (Armed Forces Institute of performed on a victim of a gunshot injury to the head as Pathology, Washington, D.C., and Dover, Del.), which early as 1977 [2] and authors such as Brogdon [3] and performs CT scans on military personnel killed in combat 274 on a routine basis evaluated the usefulness of CT in the the scanning software ATOS. Thus, a 3D surface can be assessment of high velocity gunshot victims with promis- recalculated. ing results [5]. Groups from the universities of Copenhagen Digital photography of the surface of the object of (Denmark) and Linkoping (Sweden) have started CT interest from different angles with reference markers can, scanning on corpses on a broad scale [6, 7], here again using the TRITOP software, add colour information to the with promising results. According to personal commu- otherwise black-and white 3D surface. nication, every corpse delivered to the Victorian Institute This method is applicable for the true-colour surface of Pathology (Sydney, Australia) undergoes a CT scan documentation of corpses, of objects suspected of having prior to autopsy. Also dedicated to this novel approach, caused an injury, of vehicles and of entire crime scenes. the Society for Autopsy Imaging in Japan was founded in These three-dimensional models can be compared, thus 2003 [8]. CT scanning has also been introduced into allowing for the identification of an object or structure forensic anthropology. A French group actually obtained suspected of having caused the injury [10–12]. superior results when assessing the case of a charred body Another example of the use of 3D surface data is its with respect to anthropological aspects compared with application in complex traffic accidents. A comparison of traditional methods [9]. the injuries sustained by the victim and the corresponding In Switzerland, this revolution in forensic science started structures on the vehicle (Fig. 1) helps reconstruct the off in the mid-nineties, when the Institute of Forensic course of an accident [13]. Medicine of the University of Bern started a project with the Scientific Service of the City Police of Zuerich. The aim was to document body and object surfaces in a three- MSCT dimensional (3D) fashion. A few years later, the Institute of Forensic Medicine again started a joint research project, This is indeed the most frequently used tool in our project. this time with the Institutes of Diagnostic Radiology and At present, over 200 corpses have undergone MSCT Neuroradiology of the University of Bern. This project had scanning prior to autopsy; currently, we use a six-detector- the ambitious aim of detecting forensic findings of corpses row scanner (Emotion 6, Siemens Medical Systems, using multislice CT (MSCT) and MRI, and of comparing Erlangen, Germany). Scans are usually performed with a these results with autopsy findings. 1.25-mm section thickness and a reconstruction increment This was the beginning of the Virtopsy project. Later on, of 0.7 mm. Regions of special interest, such as delicate further methods and tools were added in addition to MSCT fractures or the dentition, are scanned with thinner slice and MRI, so that now the project implements an ever thicknesses and reconstruction increments (0.63 mm and expanding variety of imaging methods. 0.5 mm, respectively). The main tools already implemented in daily forensic The CT images are read by board-certified radiologists practice are: and compared with autopsy findings acquired by board- certified forensic pathologists [14, 15]. – 3D photogrammetry-based optical surface scanning The CT examination has proven to be an invaluable tool – MSCT in three areas of forensic pathology; namely, in the – MRI. detection and demonstration of fractures, the detection of These different tools are discussed separately below. foreign bodies and the detection of gas. Detection of osseous lesions 3D photogrammetry-based optical scanning Osseous injuries obviously play an important role in forensic pathology, be it in the form of fractures, of cuts, or Photography with a reference ruler is the standard docu- of gunshot injuries. Cuts and fractures—and in the case of mentation method of injuries and injury inflicting objects whole body scans, even the fracture distribution and 3D in forensic medicine. The three-dimensionality of these pattern of dislocation—can be visualised easily and structures is reduced to a 2D level by classic photography. presented in a non-bloody form to medical laymen and However, using the TRITOP/ATOS III system (GOM, facilitate their understanding of the case (Figs. 2, 3). Braunschweig, Germany), such surfaces can be document- Furthermore, small fractures at regions of the body which ed in a 3D fashion. are difficult to access and which may be overlooked at This system consists basically of one central projection autopsy can be detected easily. Another advantage is that unit and two digital cameras mounted beside the projector. certain areas of the body not routinely dissected, such as the A fringe pattern is projected onto the surface of the object, face, can be examined with regard to fractures in a non- which is recorded by the two cameras. Based on the destructive fashion (Fig. 4), thus sparing the next of kin principle of triangulation, 3D coordinates are calculated by more psychological trauma. 275 Fig. 1a–d Three-dimensional surface scanning of a traffic accident. the step shown in a, a correctly proportioned model of the corpse is A car allegedly ran into a pedestrian whilst driving backwards. The obtained (b). After scanning the vehicle in question (c), the body man was knocked down, run over and eventually succumbed to fat model obtained in the step described in b was matched to the embolism. The body surface was scanned and fused with the CT damages of the model of the car seen in c (d) data of the skeleton (a). Thanks to the scaled proportions obtained in Detection of foreign bodies body in a 3D manner, thus facilitating the extraction at autopsy enormously. For identification, 3D data can be X-rays are routinely employed in order to detect foreign transformed to 2D projections or tomographic views; one bodies in corpses, be it projectiles [16], knife blades [17]or typical application is the creation of 2D panoramic dental medical implants, etc. (Fig. 5). MSCT has the additional images corresponding to ante-mortem radiographic docu- advantage that it can locate exactly these objects and ments [18]. Another advantage of MSCT over conventional demonstrate their topographic neighbourhood within the X-rays is that MSCT can measure the radiological density 276 MSCT can overcome most of these difficulties easily.