Legal Medicine 11 (2009) 4–9
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Injuries due to sharp trauma detected by post-mortem multislice computed tomography (MSCT): A feasibility study J. Schnider, M.J. Thali, S. Ross, L. Oesterhelweg, D. Spendlove, S.A. Bolliger * University of Bern, Centre for Forensic Imaging and Virtopsy, Institute of Forensic Medicine, Buehlstrasse 20, CH 3012 Bern, Switzerland
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Article history: Received 15 April 2008 Received in revised form 2 July 2008 Accepted 8 July 2008 Available online 23 August 2008 Keywords: Virtopsy Sharp trauma Forensic imaging Post-mortem imaging MSCT
a b s t r a c t Modern cross-sectional imaging techniques are being increasingly implemented in forensic pathology. In order to assess the practicability of such a method, namely post-mortem multislice computed tomography (MSCT) in cases of fatal cut and stab injuries, 12 corpses underwent such an examination prior to forensic autopsy. The questions regarding detection of foreign bodies, wound channels, skeletal and organ injuries, as well as the cause of death were addressed at MSCT and autopsy. The results of the two techniques revealed that post-mortem MSCT a useful tool in the assessment of such injuries. Ó 2008 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Fatal injuries due to sharp trauma are common in everyday forensic practice, be it in a homicidal, a suicidal, or in an accidental setting. The main common denominator of the injury-inflicting objects in sharp trauma is that they can pierce and slice the human body and thus cause internal damage. Death due to this harming of the body’s integrity is manifold; exsanguination by injury of blood vessels is the most frequently encountered form. However, death due to air embolism, haemopericardium, etc. are also encountered regularly. In the assessment of sharp trauma, issues such as the wound morphology, which may help to determine the type of weapon involved, the number and location of the injuries, the wound channel, the injuries inflicted to the soft tissues and the skeleton, as well as the cause of death should always be addressed in order to evaluate a possible third party involvement and to undertake an incident reconstruction. In traditional examination techniques, stab wound directions are examined by painstakingly dissecting layer by layer of the surrounding tissue. This method is excessively time-consuming and can harm previously intact structures in the immediate vicinity of the wound channel, thus complicating the differentiation between perimortal and post-mortal injury. Another method for detecting a stab wound direction consists of inserting a probe or otherwise comparable object into the wound. This method is gen* Corresponding author. Tel.: +41 31 631 84 11; fax: +41 31 631 38 33. E-mail address:
[email protected] (S.A. Bolliger). 1344-6223/$ - see front matter Ó 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.legalmed.2008.07.001
erally regarded as being obsolete, as, besides the possibility of damaging intact structures, there is a great risk of displacing potentially crucial traces into the wound depth. Gas embolism, an often encountered and vital sign in stabbing, is difficult to detect upon opening the body. These problems may be countered by the non-invasive method of post-mortem imaging. The conventional approach involving Xrays is sufficient to detect foreign bodies, gross osseous lesions and gas, but reduces a three-dimensional corpse to a two-dimensional image, thus complicating reconstructive attempts. In the past decade, post-mortem radiology has grown from a simple autopsy-assisting X-ray to a veritable forensic field of its own. With the advance of medical technologies such as computed tomography (CT) introduced by Hounsfield and Cormack in the early seventies, new possibilities became available for forensic pathologists. A first CT scan was performed on a victim of a gunshot injury to the head as early as 1977 [1] and authors such as Brogdon [2], Vogel [3] and Donchin et al. [4] have mentioned the usefulness of radiology in forensic medicine. With the invention of spiral computer tomographs, two-dimensional reconstructions of radiological images in every possible plane or even three-dimensional reconstructions are possible. These multislice computed tomographs (MSCT), which have become everyday clinical standard, have been implemented in forensic pathology by different groups with promising results [5–9], also regarding sharp trauma [10,11] and disaster victim identification [12]. In order to assess the practicability of post-mortem MSCT in assessing the main forensic questions in cases of sharp trauma,
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namely the amount and location of these injuries, the depth, the injuries inflicted to organs and skeletal structures, the wound channel and the cause of death, we performed MSCT prior to forensic autopsy on 12 corpses. 2. Materials and methods Twelve bodies of persons who died due to sharp trauma which were delivered to our institute were included in this study. Apart from one case, which showed slight signs of putrefaction after a post-mortem interval of roughly one week in a forest under cold ambient conditions, no signs of decay were seen. The male:female sex ratio was 7:5. The average age was 42 years. An overview of the case circumstances is shown in Table 1. The corpses were wrapped in artefact-free body bags (Rudolf Egli AG, Bern, Switzerland). MSCT scanning was executed on a Somatom Emotion 6 scanner (Siemens Medical Solutions, D91301 Forchheim, Germany) with 4 1.25 mm collimation. The reconstruction interval was 0.7 mm. This scanning procedure took approximately 10 min. The corpses underwent autopsy by board-certified forensic pathologists after scanning. Using a Leonardo workstation (syngo CT software, Siemens Medical Solutions, D-91301 Forchheim, Germany), two- and three-dimensional (2D and 3D) reconstructions were calculated and assessed retrospectively by two persons, of which one was a radiologist or a forensic pathologist experienced in post-mortem imaging. The duration of the interpretation of the images varied between about half an hour to over an hour, depending on the complexity of the findings. In each case, the following questions were addressed:
Detection of foreign bodies. Wound channel. Organ and skeletal injuries. Cause of death.
Internal injuries were either seen as a direct lesion within an organ or bone, or were assumed to be present in an organ lying on the wound track even if injuries to the organ itself were not visible. The determination of the cause of death was performed based on the internal injuries sustained (e.g. severe cerebral trauma with cerebral oedema or cardiac injury). The finding of a collapsed superior vena cava, main pulmonary artery, or right pulmonary artery was seen as being highly indicative of a fatal haemorrhage, according to Aghayev et al. [13]. Gas within the right cardiac chambers and in the vascular system without cardiopulmonary resuscitation attempts implied a gas (air) embolism as the most likely cause of death [14]. The results of each of the above questions obtained by postmortem MSCT were compared to the results obtained by conventional autopsies performed by board-certified forensic pathologists. Neither the persons assessing the radiological images nor the persons performing the autopsy had information on the findings of the other group. 3. Results 3.1. Detection of foreign bodies Neither MSCT nor autopsy could detect injury related foreign bodies in the examined cases. 3.2. Wound channel (Figs. 1 and 2) Of the total of 101 wound channels seen in all 12 cases at autopsy, 71 (70.3%) were detected by MSCT (Table 2). Of these, superficial lesions were seen by MSCT in only 2 of a total of 22 (9%) superficial injuries. Of the total of 79 deep wounds seen at autopsy, MSCT was able to depict 69 (87.3%). In all cases in which deep stab wounds were missed, the involved stab wounds were closely grouped. 3.3. Organ and skeletal injuries (Figs. 3 and 4)
As the question regarding the wound morphology is best answered by external examination, we refrained from addressing this topic. The wound channel through the body was examined regarding the presence of gas or blood in the soft tissues and/or distinct injuries to cartilage or bones. Foreign bodies were sought for by screening the body with scout images and subsequent 2D and 3D reconstructions.
As shown in Table 3, MSCT missed an injury to the pericardium in one case (case 6), one injury to the stomach (case 7), one to the liver (case 1) and one lesion to the brachial artery (case 3). In one case (case 9), MSCT displayed an injury to cervical vessels, but could not precisely discriminate which vessels were injured. However, MSCT sufficed in detecting lesions to the lungs, the heart, the brain, the spleen and the skeleton.
Table 1 Brief description of the cases included in this study Case no.
Age/sex
Injuries
Circumstances
CPR
PMI
1 2 3 4 5 6 7 8 9 10 11 12
26/f 83/m 30/m 32/m 15/m 23/f 51/m 41/f 76/m 40/m 26/f 61/f
Multiple stab wounds to trunk and head Stab wound to chest Stab wounds to chest and arm Stab wounds to chest Stab wound to chest Stab wounds to chest, cuts to neck Stab wounds to head, chest and abdomen Multiple stab wounds to chest Incised wound to neck Deep stab wound to back Multiple stab wounds to head, neck and thorax Multiple stab wounds to thorax, neck and upper extremities
Homicide Suicide Homicide Suicide Suicide Suicide Homicide Homicide Suicide Homicide Homicide Homicide
No No No No Yes No Yes No Yes Yes Yes No
9 10 15 168* 11 16 5 48 10 13 5 14
CPR stands for cardiopulmonary resuscitation, PMI for post-mortem interval, i.e. time between death and CT scanning in hours. The PMI given was the average of the time since death according to police and medical investigations. The asterisk in case 4 designates that the PMI here (about one week) is only a rough estimate of this corpse found in a cold forest with slight signs of putrefaction.
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4. Discussion
Fig. 1. MSCT, axial image through the chest. The stab channel (arrow) is clearly visible due to the influx of air. A small accumulation of fluid, in this case blood (X) is seen in the left thoracic cavity.
Fig. 2. MSCT, sagittal view of the chest. Here, the stab wound (solid arrow) contrasts well to the lung tissue due to the bleeding into the wound channel. Note also the pneumothorax (dashed arrow) and the blood in the thoracic cavity (X).
3.4. Cause of death (Figs. 5 and 6) Almost all relevant findings noted at autopsy regarding possible causes of death could be detected or at least clearly assumed. Furthermore, in six of the 12 cases, a gas (air) embolism was noted in MSCT but not at autopsy (Table 4). In one case (case 1) MSCT detected signs of extensive, potentially lethal blood aspiration. Although no typical gastric erosions were seen at autopsy in case 4, the additional cause of death ‘‘hypothermia” was postulated due to the findings of adjuvant histology (microhaemorrhages and discoid necrosis of the deep abdominal muscles) and chemical analyses (ketone bodies in the urine). These were missed by MSCT.
Regarding wound channels, MSCT was a valuable tool in detecting deep, potentially dangerous or even lethal stab wounds and their course through the body and the hereby injured structures; 87.3% of such injuries could be detected with MSCT. The missed wound channels had one common feature: they belonged to a series of closely grouped injuries. It is very likely that the close proximity of these lesions sufficed to obscure certain lesions at MSCT and therefore led to the erroneous radiological assumption of there being fewer deep lesions. On the other hand, superficial stab wound channels and cuts were missed frequently. This was especially true in situations of closely grouped lesions such as in hesitation cuts or stabs. This fact may be due to the limited resolution of the CT scanner, a shortcoming that may be countered with more modern, high-resolution CT units. Another reason may be the scanning technique; in post-mortem MSCT, the body is placed in an anatomically neutral position, with the arms placed more or less beside the supine trunk. However, certain superficial findings may be obscured by other structures such as the trunk and may be missed by this static imaging method, which conventional autopsy – during which the body part is placed according to the needs of the examiner – obviously does not have. Nevertheless, post-mortem imaging does not replace an external examination, but rather aims at providing additional information. The MSCTs shortcoming, especially regarding the detection of superficial and externally readily assessable injuries, may be countered by a thorough visual inspection of the corpse. Another aspect is the stab channel depth. In hard structures, such as the skull, MSCT can measure a wound channel accurately and easily. However, great caution should be exerted when measuring the channel depth in soft body regions; due to the elasticity the wound channel may be even longer than the blade involved. In contrast to the shortcoming regarding superficial lesions, most relevant injured structures were detected by MSCT or could be clearly assumed. Although one pericardial injury was missed, the more important cardiac lesions were invariably seen. Regarding the detection of lesions to the cervical vessels, MSCT could not discriminate between arterial and venous injury of case 9 and missed the injury of the brachial artery in case 3. However, MSCT-based post-mortem angiography, as mentioned in recent literature [15,16], may overcome this difficulty and depict the vascular system in a minimally invasive, precise fashion. As lesions to the skeleton may give clues as to the involved weapon type and are comparatively frequent [17,18], it is important that one readily detects these. MSCT detected all skeletal injuries easily. Therefore, by having a certain idea of what to expect, further examinations such as an autopsy can be planned more carefully, thus leading to an improved examination. Regarding the cause of death, MSCT was very efficient. In eight of the 12 cases, MSCT detected a gas embolism, a sometimes tricky diagnosis to be made by traditional autopsy techniques. One conventional method consists of puncturing the heart whilst submerged in water in the pericardial sack; if bubbles rise to the water surface, the presence of gas in the cardiac chamber is confirmed. Another method is the aspiration of intracardial gas by a so-called aspirometer [19]. This method allows for the quantification of gas within the cardiac chambers and allows for a chemical analysis, thus making a discrimination between air and other gases, such as putrefaction gas, possible [20]. With the first rapid method the gas is lost, thus making a precise differentiation between air and putrefaction by chemical analysis impossible. Furthermore, this method will lead to a loss of the intracardial blood for toxicological analysis. The second method is cumbersome and time-consuming and therefore rarely performed routinely.
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J. Schnider et al. / Legal Medicine 11 (2009) 4–9 Table 2 Comparison of the results regarding the detection of wound channels with MSCT and autopsy Case no.
Results of MSCT
Results of autopsy
4
10 deep stab wounds to thorax 2 deep stab wounds to abdomen 1 deep stab wound to mandibula 1 deep stab wound to thorax 1 deep stab wound to arm 1 deep stab wound to thorax 2 deep stab wounds to thorax
5 6
1 deep stab wound to thorax 3 deep stab wounds to thorax
7
3 deep stab wounds to head 2 deep stab wounds to thorax 1 deep stab wound to abdomen 13 deep stab wounds to thorax 1 deep incised wound to neck 1 deep stab wound to thorax 2 subcutaneous stab wounds to head 6 deep stab wounds to thorax 8 deep stab wounds to neck 1 deep stab to neck 7 deep stab wounds to thorax 4 deep stab wounds to arms
10 deep stab wounds to thorax 2 deep stab wounds to abdomen 1 deep stab wound to mandibula 1 deep stab wound to thorax 1 deep stab wound to arm 1 deep stab wound to thorax 2 deep stab wounds to thorax 5 subcutaneous stab wounds to thorax 1 deep stab wound to thorax 3 deep stab wounds to thorax 5 subcutaneous stab wounds to thorax 5 subcutaneous incised wounds to neck 3 deep stab wounds to head 2 deep stab wounds to thorax 1 deep stab wound to abdomen 13 deep stab wounds to thorax 1 deep incised wound to neck 1 deep stab wound to thorax 2 subcutaneous stab wounds to head 9 deep stab wounds to thorax 8 deep stab wounds to neck 1 deep stab to neck 7 deep stab wounds to thorax 11 deep stab and incised wounds to arms 5 subcutaneous stab wounds to thorax
1
2 3
8 9 10 11
12
Fig. 4. Axial MSCT image of a chest. The anterior wall of the left ventricle displays an injury (circle). The arrow designates an emphysema of the chest muscles. Note also the haemothorax on the right (X). Fig. 3. MSCT, 3D bone reconstruction showing lesions to the ribs (arrows).
These problems can easily be overcome by MSCT. The sectional images can depict the presence of gas in a rapid fashion, whilst 3D reconstructions are able to display the amount of the gas reliably [14] as well as the gas distribution in the blood vessels and the cardiac chambers. This distribution, namely whether it is omnipresent such as in putrefaction, or restricted to the right heart and its blood vessels, a finding indicative of a gas embolism, may make a certain differentiation of the nature of the gas – namely putrefaction or other (such as air) possible. The above-mentioned radiological findings do, however, not prove that the involved gas is indeed air. In order to do so, an aspiration of the gas in question with sub-
sequent chemical analysis can be performed after MSCT confirmation of the presence of the gas. Caution should be exerted when interpreting gas in the vascular system in persons who received cardiopulmonary resuscitation. In these cases, air can be forced into and along the vessels, thus mimicking an active embolisation of air. Therefore, after intense resuscitation attempts, air in the vessels can be due to an air embolism, or be a merely peri/post-mortem (resuscitation-caused) phenomenon. CT of cases 9 and 11 both presented gas within the right heart and blood vessels. Although both cases were experienced resuscitation attempts, the jugular vein injury in case 9 makes a gas embolism highly probable. In case 11, the pulmonary lesions may have caused an arterio-venous shunt with gas entering the systemic vascular bed. In this case, it
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Table 3 Comparison of the major injuries seen at MSCT and autopsy concerning different organ systems Case no.
MSCT
Autopsy
1 2 3 4 5 6 7 8 9 10 11 12
Lungs, pneumothorax,liver Heart No organ lesion Lungs Heart Lungs Brain, lungs Lungs, 2 ribs Cervical vessels 1 rib, lungs, heart Sternum, 2 ribs, lungs Lungs, 2 ribs, spleen, kidney
Lungs, liver Heart Right A. brachialis Lungs Heart Lungs, pericardium Brain, lungs, stomach Lungs, 2 ribs Jugular vein 1 rib, lungs, heart Sternum, 2 ribs, lungs Lungs, 2 ribs, spleen, kidney
The amount of lesions per organ and the location is not shown.
Fig. 6. Axial MSCT image of the chest. The pericardial sack is filled with blood (solid arrow), the right cardiac chambers contain gas (dashed arrow) as a sign indicating an air embolism. The left thoracic cavity contains a fluid which has separated to a hyperdense (black X) and a hypodense (white X) layer. This sedimentation is typical for large haemorrhages, in which the more radioopaque corpuscular components of the blood sink, thus giving rise to a hypodense, cell-poor supernatant.
Table 4 Comparison of the causes of death as concluded by MSCT and autopsy Case no. 1 2 3 4 5 6 7 8 9 10 11 12
MSCT
Autopsy
Exsanguination, gas embolism, pneumothorax, (blood?) aspiration Haemopericardium, gas embolism Exsanguination, gas embolism Exsanguination Exsanguination Exsanguination, gas embolism Central respiratory paralysis due to cerebral oedema Exsanguination, gas embolism Exsanguination, gas embolism Exsanguination Exsanguination, gas embolism Exsanguination, gas embolism
Exsanguination, gas embolism, pneumothorax, blood aspiration Haemopericardium Exsanguination Exsanguination, hypothermia Exsanguination Exsanguination Central respiratory paralysis due to cerebral oedema Exsanguination Exsanguination Exsanguination Exsanguination, gas embolism Exsanguination
Fig. 5. MSCT, axial minimum intensity projection image of a head. Note the gasfilled blood vessels corresponding to lethal air embolism. As there was no open oval foramen of the heart, this gas must have entered the systemic vascular bed via stabinduced arterio-venous shunts.
Acknowledgements is not quite clear whether this intravascular gas is a pure ante-mortem or possibly resuscitation-induced (or both) phenomenon. Furthermore, if MSCT is combined with image-guided tissue sampling for histology and chemical analyses, the missed diagnosis ‘‘hypothermia”, which, incidentally was also missed morphologically at autopsy and only detected with adjuvant methods, could have been detected. 5. Conclusions In addition to a thorough external inspection, post-mortem MSCT may be a useful tool in the assessment of sharp trauma casualties. By showing certain regions of interest, autopsy planning may be facilitated and the overall detection frequency of traumatic findings increased. This may be especially true for post-mortem MSCT investigations combined with post-mortem whole-body angiography.
The authors thank Mr. Roland Dorn and Urs Koenigsdorfer for invaluable help during autopsy procedures and Renate and Werner Bolliger, Ph.D., for assistance in manuscript preparation. References [1] Wullenweber R, Schneider V, Grumme T. A computer-tomographical examination of cranial bullet wounds. Z Rechtsmed 1977;80:227–46. [2] Brogdon BG. Forensic radiology. Boca Raton: CRC press; 1998. [3] Vogel H. Gewalt im Röntgenbild: Befunde bei Krieg, Folter und Verbrechen. Echomed 1997;41:13–42. [4] Donchin Y, Rivkind AI, Bar-Ziv J, Hiss J, Almog J, Drescher M. Utility of postmortem computed tomography in trauma victims. J Trauma 1994;37:552–5. [5] 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 multisclice computed tomography (MSCT) and magnetic resonance imaging (MRI) – a feasibility study. J Forensic Sci 2003;48:386–403. [6] Poulsen K, Simonsen J. Computed tomography in connection with medicolegal autopsies. Forensic Sci Int 2007;171:190–7.
J. Schnider et al. / Legal Medicine 11 (2009) 4–9 [7] Ljung P, Winskog C, Persson A, Lundstrom C, Ynnerman A. Full body virtual autopsies using a state-of-the-art volume rendering pipeline. Trans Vis Comput Graph 2006;12:869–76. [8] Levy AD, Abbott RM, Mallak CT, Getz JM, Harcke HT, Champion HR, et al. Virtual autopsy: preliminary experience in high-velocity gunshot wound victims. Radiology 2006;240:522–8. [9] Hayakawa M, Yamamoto S, Motani H, Yajima D, Sato Y, Iwase H. Does imaging technology overcome problems of conventional postmortem examination? A trial of computed tomography imaging for postmortem examination. Int J Legal Med 2006;120:24–6. [10] Oesterhelweg L, Ross S, Spendlove D, Schoen CA, Christe A, Thali MJ, et al. Virtopsy: fatal stab wound to the skull – the relevance of ante-mortem and post-mortem radiological data in case reconstructions. Leg Med 2007;6:314–7. [11] Thali MJ, Schwab CM, Tairi K, Dirnhofer R, Vock P. Forensic radiology with cross-section modalities: spiral CT evaluation of a knife wound to the aorta. J Forensic Sci 2002;47:1041–5. [12] Blau S, Robertson S, Johnstone M. Disaster victim identification: new applications for postmortem computed tomography. J Forensic Sci 2008 [Epub ahead of print]. [13] Aghayev E, Sonnenschein M, Jackowski C, Thali MJ, Buck U, Yen K, et al. Postmortem radiology of fatal hemorrhage: measurements of cross-sectional
[14]
[15]
[16]
[17] [18] [19] [20]
9
areas of major blood vessels and volumes of aorta and spleen on MDCT and volumes of heart chambers on MRI. AJR 2006;187:209–15. Jackowski C, Thali MJ, Sonnenschein M, Aghayev E, Yen K, Dirnhofer R, et al. Visualization and quantification of air embolism structure by processing postmortem MSCT data. J Forensic Sci 2004;49:1339–42. Jackowski C, Sonnenschein M, Thali MJ, Aghayev E, von Allmen G, Yen K, et al. Virtopsy: postmortem minimally invasive angiography using cross section techniques – implementation and preliminary results. J Forensic Sci 2005;50:1157–86. Ross S, Spendlove D, Bolliger S, Christe A, Oesterhelweg L, Grabherr S, et al. Postmortem whole-body CT angiography: evaluation of two contrast media solutions. Am J Roentgenol 2008;190:1380–9. Banasr A, Lorin de la Grandmaison G, Durigon M. Frequency of bone/cartilage lesions in stab and incised wounds fatalities. Forensic Sci Int 2003;131:131–3. Beaumont E, O’Byrne P. Bone injuries by stab wounds. Report of 19 cases. J Med Legale Droit Med 1999;7–8:581–5. Mallach HJ, Schmidt WK. Ueber ein quantitatives Verfahren zum Nachweis der Luft-oder Gasembolie. Beitr Ger Med 1980;38:409–19. Keil W, Bretschneider K, Patzelt D, Behning I, Lignitz E, Matz J. Luftembolie oder Fäulnisgas? Zur Diagnostik der cardialen Luftembolie an der Leiche. Beitr Ger Med 1980;38:395–408.
