VIRTOPSY – The Swiss virtual autopsy approach

Legal Medicine 9 (2007) 100–104 www.elsevier.com/locate/legalmed VIRTOPSY – The Swiss virtual autopsy approach Michael J. Thali *, Christian Jackowski, Lars Oesterhelweg, Steffen G. Ross, Richard Dirnhofer Institute of Forensic Medicine, Center of Forensic Imaging/Virtopsy, University of Berne, Switzerland Abstract The aim of the VIRTOPSY project (www.virtopsy.com) is utilizing radiological scanning to push low-tech documentation and autopsy procedures in a world of high-tech medicine in order to improve scientific value, to increase significance and quality in the forensic field. The term VIRTOPSY was created from the terms virtual and autopsy: Virtual is derived from the Latin word ‘virtus’, which means ‘useful, efficient and good’. Autopsy is a combination of the old Greek terms ‘autos’ (=self) and ‘opsomei’ (=I will see). Thus autopsy means ‘to see with ones own eyes’. Because our goal was to eliminate the subjectivity of ‘‘autos’’, we merged the two terms virtual and autopsy – deleting ‘‘autos’’ – to create VIRTOPSY. Today the project VIRTOPSY combining the research topics under one scientific umbrella, is characterized by a trans-disciplinary research approach that combines Forensic Medicine, Pathology, Radiology, Image Processing, Physics, and Biomechanics to an international scientific network. The paper will give an overview of the Virtopsy change process in forensic medicine.  2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Forensic radiology; Virtopsy; Virtual autopsy; Autopsy imaging 1. Introduction The application of imaging methods for non-invasive documentation and analysis of relevant forensic findings in living and dead persons has lagged behind the enormous technical development of imaging methods. There are only a few textbooks dealing with forensic radiology [1,2]. Most of these textbooks concentrate on classical roentgenographic methods and hardly cover the newer sectional imaging techniques of computed tomography and magnetic resonance imaging in detail. Forensic radiology, including all techniques and their many uses for forensic purposes, now is a rapidly growing interdisciplinary subspecialty of both forensic medicine and radiology. Shortly after the communication of the detection of X-rays by Conrad Roentgen the new non-invasive technique was used for forensic documentation purposes. But modern cross* Corresponding author. Tel.: +41 31 631 84 12; fax: +41 31 631 38 33. E-mail address: michael.thali@irm.unibe.ch (M.J. Thali). URL: www.virtopsy.com (M.J. Thali). section imaging is still underutilized in forensics, mainly due to the unawareness of its potential in forensic science but also to the cost and the limited access to and training for these newer modalities, such as Computer Tomography-CT, including spiral multislice, and Magnetic Resonance Imaging-MRI. 2. The Swiss virtual autopsy project (VIRTOPSY) 2.1. Materials and methods The Institutes of Forensic Medicine and of Diagnostic Radiology of the University of Bern, Switzerland, started a research project in 2000, with the hypothesis that non-invasive imaging might predict autopsy findings and maybe give additional information. The responsible justice department and also the ethics committee of the University of Bern approved the study. In this joint project called ‘‘Virtopsy’’ [11] we used the newest generation of: 1344-6223/$ - see front matter  2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.legalmed.2006.11.011 M.J. Thali et al. / Legal Medicine 9 (2007) 100–104 101 • fracture systems, • pathologic gas collections (whether air embolism, subcutaneous emphysema after trauma, hyperbaric trauma, or decomposition effects), • and it also shows gross tissue injury. Fig. 1. Forensic CT examination of a dead body at the University of Bern. Post-processing on commercial scanning workstation with 3D SSD (Surface Shade Display) and VR (Volume Rendering) can provide useful visualization for court trial (Fig. 2). For example, in gunshot cases the determination of entrance and exit wounds is possible based on the characteristic fracture pattern with inward or outward beveling of the bone respectively. CT and MRI are excellent tools to visualize bullet tracts with hemorrhage (Figs. 2 and 3). Metal artifacts due to the • Multidetector row or Multislice Spiral Computer Tomography (MSCT), • and 1.5 Tesla MR scanner from GE with Spectroscopy software. In special situations bone tissue specimens were examined on a Micro-CT and Micro-MR system. The Micro-CT is developed and built at the Institute of Medical Physics Erlangen, Germany. This Micro-CT scanner can image a 3D volume with an isotropic resolution for resolution ranges from 10 to 100 lm. The system is capable of examining samples with diameters from 4 to 40 mm. The Micro-MR studies were performed on a Bruker DMX spectrometer (Bruker Biospin MRI, Inc., Billerica, MA) coupled to a wide-bore magnet operating at 9.4 T (400 MHz for protons). At the beginning in 2000, all dead bodies were transported by undertakers to the hospital for the CT and MRI scanning. Wrapping the corpses in artifact-free body bags, as requested by the ethics committee, preserved anonymity of the deceased. Since 2005 the Forensic Institute at the University of Bern has its own Siemens MSCT scanner (Siemens high speed type 6 thin-slices at every rotation) for the postmortem scanning. By now, 100 forensic cases have received a full body examination by CT and MRI before autopsy (Fig. 1). The results of CT and MRI were correlated with the findings of autopsy [3,4,7–10], analyzing the indications of each type of exploration depending on the expected pathology. Fig. 2. 3D-MSCT of an gunshot injury. The exit wound is visible by looking through the entrance wound. 2.2. Results The scan times are short from 1 to 10 min. The correlation with the forensic autopsy findings showed: 2.2.1. Computer Tomography-CT The CT depending on the slice thickness and the volume to be covered, have been found a superior tool for 2D and 3D documentation and analysis of Fig. 3. Gunshot injury to the head: MRI is showing bullet wound track in the cerebellum (arrow). 102 M.J. Thali et al. / Legal Medicine 9 (2007) 100–104 bullet can appear on CT images; these effects will be reduced in the near future by metal artifact reduction algorithms. As compared to clinical imaging in trauma or forensic victims, the major drawback of postmortem CT is the lacking availability of intravenous contrast enhancement after circulatory arrest, which makes analysis of parenchyma and vascular injury much more difficult, less sensitive and less specific. 2.2.2. Magnetic Resonance-MR In demonstrating soft tissue injury, neurological and non-neurological organ trauma, and non-traumatic pathology, the MRI (Figs. 4 and 5), compared to CT, clearly had a • higher sensitivity, • higher specificity, and • higher accuracy Studies of child abuse victims confirm the sensitivity of postmortem MRI for contusion, shearing injuries and subdural hematoma. Differences in morphology and signal characteristics between antemortem and postmortem MRI do exist; however, they have not yet been studied systematically. If the results of clinical MRI can be transferred to postmortem analysis, there is a great future for non-destructive analysis of visceral pathology, such as cardiac (including coronary), pulmonary and hepatic disease. 2.2.3. Magnetic Resonance Spectroscopy-MRS Finally, MRS, combined with MRI, has a great potential in documenting pre-terminal and postmortem metabolite concentrations in tissues. Since decomposition continuously changes the concentration of chemical compounds postmortem, MRS might be helpful in determining the time of death [13–15]. 3. Forensic application of radiological micro-imaging – Virtual histology In many cases, the resolution of clinical scanners is not sufficient to answer questions relevant to forensic medicine nondestructively. This favors the idea of using microscoping non invasive imaging methods with their much higher resolution to visualize forensic specimens [4]. We have used microtomography of small object or micro-CT in a forensic case of a knife’s blade inside cortical and trabecular bone to determine the injury pattern and the weapon involved [4,12]. In forensic soft tissue injury, retinal hemorrhage and electric injury to the skin were studied by micro-MR (MR microscopy) [5,6]. We expect these new radiological cross-sectional micro-imaging methods to have a comparable impact on (forensic) histopathology, leading to virtual histology. 4. Data management and teleconsultation Fig. 4. (a) Autopsy image: knife wound injury to the heart (arrow). (b) Corresponding finding in MRI: knife wound to the heart (arrow). The Virtopsy project generates enormeous numbers of digital DICOM data that can easily be archived, transmitted on a network, copied, quantitatively analyzed and postprocessed on a workstation. Digital format not only allows compact digital archiving but also cuts the cost of films, of film handling and of archive space as soon as an institute is prepared for the digital solution (PACS = picture archiving and communication system). M.J. Thali et al. / Legal Medicine 9 (2007) 100–104 103 5. Conclusion and outlook Evidently, imaging techniques are nowadays excellent tools for forensic medicine. Similar to inspection and photography but in contrast to other tools, they are able to freeze the findings at the moment of investigation without causing any damage. Freezing means permanent (analogue or digital) preservation as a document of proof, whether the victim is dead and undergoing postmortem decay or surviving and loosing evidence due to healing. Causing no damage is an essential prerequisite in a living person that is fulfilled indisputably. Even in dead persons, nondestructive documentation is important for two reasons: 1. First, it brings its information without precluding any other conservative or destructive forensic investigation. 2. Second, it can be used in cultures and situations where autopsy is not tolerated by religion or rejected by family members. Whether and to what degree radiological minimally invasive ‘‘virtual autopsy’’ will in defined situations replace the classical dissection technique will be decided in the near future. Two innovative forensic documentation methods are rising at the horizon: 1. the combination of sectional imaging with surface documentation methods, such as photogrammetry and 3D optical scanning, and 2. the combination of noninvasive imaging with minimally invasive image-guided tissue sampling from any body location needed [7–10]. Tissue samples can be used for cytology, histology, chemical, and microbiological analysis. Radiologic virtual autopsy offers other advantages, such as Fig. 5. (a) Autopsy image: rupture of aorta (arrow). (b) Corresponding finding in MRI: aortic rupture (arrow). Postprocessing is another tool that opens new ways of analyzing imaging data. Image contrast can be enhanced, distances, areas and volumes measured, and advanced software programs will help the doctor find tiny pathologic findings. Finally, teleradiology will open new teleconsulting services in the near future. In Switzerland, the aspects of teleconsulting of such forensic data is under discussion No doubt, forensic radiology will similarly share the advances of clinical imaging. 1. an easy examination of bodies contaminated by infection, toxic substances, radionuclides or other biohazards. 2. 2D and 3D postprocessing incredibly helps to visualize the findings to people not present during the examination, e.g., in court. 3. Complete, easily retrievable digital archives and teleconsultation will support the process of quality improvement. To support this process we founded the Technical Working Group Forensic Imaging Methods (www.twgfim.com). Forensic Imaging will be an exciting science in the future. Acknowledgements Thanks go to all the Virtopsy research team members (see [11]). 104 M.J. Thali et al. / Legal Medicine 9 (2007) 100–104 References [1] Brogdon BG. Forensic Radiology. Boca Raton: CRC Press; 1998. [2] Hart BL, Dudley MH, Zumwalt RE. Postmortem cranial MRI and autopsy correlation in suspected child abuse. Am J Forensic Med Pathol 1996;17(3):217–24. [3] Thali MJ, Yen K, Schweitzer W, Vock P, Boesch C, Ozdoba C, et al. Virtopsy, a new imaging horizon in forensic pathology: virtual autopsy by postmortem multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) – a feasibility study. J Forensic Sci 2003;48(2):386–403. [4] Thali MJ, Taubenreuther U, Karolczak M, Braun M, Brueschweiler W, Kalender WA, et al. Forensic microradiology: micro-computed tomography (Micro-CT) and analysis of patterned injuries inside of bone. J Forensic Sci 2003;48(6):1336–42. [5] Thali MJ, Dirnhofer R, Becker R, Oliver W, Potter K. Is ‘virtual histology’ the next step after the ’virtual autopsy’? Magnetic resonance microscopy in forensic medicine. Magn Reson Imaging 2004;22(8):1131–8. [6] Thali M, Potter K, Dirnhofer R. From Virtopsy to Micro-Virtopsy: Virtual Forensic Histology. 81th Annual Congress of the German Forensic Society, in Rostock, Germany, 2003. [7] Thali M, Braun M, Kneubuehl B, Brueschweiler W, Vock P, Dirnhofer R. Improved vision in forensic documentation: Forensic, 3D/CAD-supported photogrammetry of bodily injury external surfaces, combined with volumetric radiologic scaninng of bodily injury internal structures to provide more leads and stronger forensic evidence. Oliver W. 3D visualisation for data exploration and decision making. SPIE 2000:213–21. [8] Thali M, Braun M, Dirnhofer R. Optical 3D surface digitizing in forensic medicine: 3D documentation of skin and bone injuries. Forensic Sci Int 2003;48(6):1356–65. [9] Thali M, Braun M, Wirth J, Vock P, Dirnhofer R. 3D Surface and 3D body documentation in forensic medicine: 3D/CAD photogram- [10] [11] [12] [13] [14] [15] . metry merged with 3D radiological scanning. J Forensic Sci 2003;48(6):1356–65. Thali MJ, Braun M, Buck U, Aghayev E, Jackowski C, Vock P, et al. VIRTOPSY – scientific documentation, reconstruction and animation in forensic: individual and real 3D data based geometric approach including optical body/object surface and radiological CT/MRI scanning. J Forensic Sci 2005;50(2):428–42. www.virtopsy.com. Microphotonics. http://www.microphotonics.com/skymto.html. Ith M, Bigler P, Scheurer E, Kreis R, Hofmann L, Dirnhofer R, et al. Observation and identification of metabolites emerging during postmortem decomposition of brain tissue by means of in situ 1H-magnetic resonance spectroscopy. Magn Reson Med 2002;48(5):915–20. Scheurer E, Ith M, Dietrich D, Kreis R, Husler J, Dirnhofer R, et al. Statistical evaluation of time-dependent metabolite concentrations: estimation of post-mortem intervals based on in situ 1H-MRS of the brain. NMR Biomed 2005;18(3):163–72. Delnomdedieu M, Hedlund LW, Johnson GA, Maronpot RR. Magnetic resonance microscopy – A new tool for the toxicologic pathologist. Toxicol Pathol 1996;24:36–44 Prof. Dr. med. Michael Thali, Executive MBA HSG, is working since 1995 in forensic medicine. He has a two year fellowship in clinical radiology. In 2001/2002 he was a fellow at the Armed Forces Institute of Pathology (AFIP) in Washington DC. He wrote many virtual autopsy papers (see www.virtopsy.com). Since February 2006 he is full professor for forensic medicine at the University of Bern, Switzerland. He is director of the ‘‘Center for Forensic Imaging’’ at the Institute of Forensic Medicine Bern.