Legal Medicine 18 (2016) 25–30
Contents lists available at ScienceDirect
Legal Medicine journal homepage: www.elsevier.com/locate/legalmed
The importance of post-mortem computed tomography (PMCT) in confrontation with conventional forensic autopsy of victims of motorcycle accidents Artur Moskała ⇑, Krzysztof Woz´niak, Piotr Kluza, Karol Romaszko, Oleksij Lopatin Chair and Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków, Poland
a r t i c l e
i n f o
Article history: Received 14 November 2015 Received in revised form 22 November 2015 Accepted 23 November 2015 Available online 23 November 2015 Keywords: Forensic medicine Forensic autopsy Post-mortem computed tomography PMCT Motorcycle accidents
a b s t r a c t Since traffic accidents are an important problem in forensic medicine, there is a constant search for new solutions to help with an investigation process in such cases. In recent years there was a rapid development of post-mortem imaging techniques, especially post-mortem computed tomography (PMCT). In our work we concentrated on a potential advantage of PMCT in cases of motorcycle accident fatalities. The results of forensic autopsy were compared with combined results of the autopsy and PMCT to check in which areas use of these two techniques gives statistically important increase in number of findings. The hypothesis was confirmed in case of pneumothorax and fractures of skull, spine, clavicle, scapula, lower leg bones. As for majority of other bone fractures locations and brain injures there were single cases with pathologies visible only in PMCT, but too few to reach expected level of p-value. In case of injuries of solid organs and soft tissues statistical analysis did not confirmed any advantage of unenhanced PMCT use. On the whole it has been shown that PMCT used as an adjunct to forensic autopsy can cause an increase in information about vitally important regions in case of motorcycle accident fatalities. Ó 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction According to the statistics published by the Polish Police Headquarters, the number of victims of traffic accidents involving motorcycles in recent years has remained more or less stable, with a slight downward trend. In the period covered by this publication, the figure was more than 200 deaths per year [1]. In each case of traffic accident it is not only necessary to determine the cause of death, but it is also required to describe in detail all the injuries, both external and internal in a very wide range. This is essential for further proper reconstruction of the course of events. Therefore, all the time forensic medicine seeks new methods that can improve the accuracy of reporting findings, as well as to improve its understanding to the non-professionals [2,3]. In this context, the importance of post-mortem imaging application in forensic medicine has been growing in recent years [4,5]. This especially applies to computed tomography, mainly due to easier access to CT scanners. Detailed analysis of the extent of how this technique complements the conventional autopsy in cases of traffic accident victims will allow to determine in what aspects its usefulness is of utmost importance. ⇑ Corresponding author. E-mail address: [email protected] (A. Moskała). http://dx.doi.org/10.1016/j.legalmed.2015.11.005 1344-6223/Ó 2015 Elsevier Ireland Ltd. All rights reserved.
The aim of the study was to compare the results of a conventional autopsy in cases of deaths of motorcycle riders to the results of the PMCT and to specify those areas where there were significant differences between the PMCT accuracy alone and this two techniques analyzed together. This would be the base to determine the extent to which PMCT examination is especially useful in the analysis of deaths of victims of motorcycle accidents. In future it can help to use this technique in a more targeted way, to increase as much as possible the accuracy of the whole post-mortem examination. 2. Material and methods We evaluated 48 cases of victims of motorcycle accidents that were autopsied in our Department of Forensic Medicine in the years 2012–2014. In every case conventional forensic autopsy and PMCT examinations were performed under an agreement with the prosecutor’s office as a standard forensic procedure, and our PMCT research program has been under surveillance of the relevant Bioethics Committee. The youngest victim was 7 y.o. and the oldest was 58 y.o. Out of the analyzed cases, 43 were males and 5 were females. The post mortem interval, between death and autopsy, was between 1 and 3 days. In each case an autopsy was preceded by a PMCT examination with Siemens Somatom
26
A. Moskała et al. / Legal Medicine 18 (2016) 25–30
only during PCMT examination. And in the third part these cases where injuries detected in both techniques are shown. For each number of cases a specified percentage was given, in relation to the whole number of cases with a concrete injury stated in the first column. The last column shows the calculated p-value. If a fluid was present in a body cavity, its attenuation coefficient was measured. In all cases results were above 50 Hounsfield units, which allowed to classify it as blood [6]. Later on presence of blood was confirmed during the autopsy.
Emotion 16 CT scanner. The scan parameters were: 130 kV, 240 mAs, collimation 16 0.6, pitch 0.85. The study covered the entire body in three series: the first from the top of the head to the shoulders, the second from the neck, above the shoulders (present in the previous series) to the height of the pubic symphysis and the third series covered the pelvis and lower limbs. The slice thickness was set to 0.75 mm for the head series and as for the trunk and lower extremities, it was set to 1.5 mm. For each range reconstructions were performed in the soft tissue and bone window (kernel H31s and H70s), as well as the pulmonary window for the thorax (kernel B70s). The results of the study were evaluated with the OsiriX software v.5.5.1 (Pixmeo SARL, Switzerland). The autopsy was carried out in each case by a physician with a speciality in the field of forensic medicine. PMCT (MPR, 3D reconstructions) results were confronted with the results of the autopsy by two board certified specialists in forensic medicine with longterm experience in PMCT interpretation (since 2009). We assessed the compliance of internal injuries in the area of the head, neck, chest, abdomen, pelvis and the extremities. The evaluation covered analysis of bone structures, soft tissues, presence of liquids and gases in the body cavities and pathological spaces. We compared the frequency of occurrence of injured structures in the abovementioned areas. In the statistical analysis we used the McNemar’s test, to verify following hypotheses:
3.1. Injuries of bone structures Table 1 presents a summary of bone injuries. Skull fractures were found in 67% of cases. More fractures were localized with PMCT in craniofacial area and at a cranial base. The circular fracture of the base of the skull draws particular attention, as this kind of injury is not always easy to locate during an autopsy, while it is clearly visible on 3D reconstructions (Fig. 1). In some cases, it was not a complete circle but a fracture beginning in the form of a hinge within the sphenoid bone and pyramids of temporal bones, extending towards the rear but not closing the circle. In 5 cases, fracture of condyles of the occipital bone was found on PMCT reconstructions. In a standard autopsy this may be much more difficult to verify because of the complicated access to the region of the skull base. The autopsy revealed more fractures within the base of the skull, especially in the anterior cranial fossa, where the thin bones hampered the assessment of post-traumatic changes in the PMCT examination. In general a statistically significant difference was found, indicating that a bigger number of skull fractures was detected by the combination of the two techniques (Fig. 2). As for the trunk, rib fractures were the most common bone injuries which occurred in 81.2% of cases. It should be noted that the overall percentage of incidence of fractures of the ribs exceeds 100%. This is due to the fact that in some cases different fractures were reported at the same time only by autopsy or only by PMCT. For this reason, we did not set the p-value for this group of injuries. The cases where more rib fractures were found during autopsy consisted mainly of fractures in the front lines and next to sternum. While the cases where more injuries were visible in the CT were related to fracture in posterior lines and next to the spine [7]. Spine fractures occurred in 68.8% of cases. Injuries visible only during autopsy were located at the level of the intervertebral discs,
H0 – use of post-mortem CT does not significantly increase the total number of findings in relation to the results of the autopsy alone. H1 – use of post-mortem CT does significantly increase the total number of findings in relation to the results of the autopsy alone. The level of significance was set at p < 0.05. Calculations were performed using Statistica (StatSoft, USA) v.12.5 software. 3. Results The results are presented in tables. The first column shows the total number of cases with given post-traumatic change and the percentage of the total number of cases. In subsequent columns we present number of cases where the injury was found only during autopsy, followed by number of cases with injuries found
Table 1 Bone injuries.
Skull Spine (without sacral bone) Ribs Sternum Clavicle Scapula Humerus Forearm bones Pubic bones Ischium bones Sacrum bone Iliac bones Sacroiliac joints Pubic symphysis Femurs Lower leg bones
I
II
Cases with injury n = 48 (%)
Injury distributions
III
IV
V
VI
VII
VIII
Cases with injury detected only during autopsy
Cases with injury detected only during autopsy (%)
Cases with injury detected only during PMCT
Cases with injury detected only during PMCT (%)
Cases with injury detected with both techniques
Cases with injury detected with both techniques (%)
p-value
32 (67.0) 33 (68.8) 39 (81.2) 16 (33.3) 15 (31.3) 15 (31.3) 12 (25.0) 15 (31.3) 12 (25.0) 4 (8.3) 4 (8.3) 5 (10.4) 8 (16.7) 7 (14.6) 15 (31.3) 22 (45.8)
3 7 18 8 0 0 3 3 0 0 0 0 1 1 0 0
9.4 21.2 46.2 50.0 0 0 25.0 20.0 0 0 0 0 12.5 14.3 0 0
12 22 19 1 8 13 0 5 5 2 2 0 1 1 3 10
37.5 66.7 48.8 6.3 53.3 86.7 0 33.3 41.7 50 50 0 12.5 14.3 20 45.5
17 4 7 7 7 2 9 7 7 2 2 5 6 5 12 12
53.1 12.1 17.9 43.7 46.7 13.3 75.0 46.7 58.3 50 50 100 75 71.4 80 54.5
0.02
Contents lists available at ScienceDirect
Legal Medicine journal homepage: www.elsevier.com/locate/legalmed
The importance of post-mortem computed tomography (PMCT) in confrontation with conventional forensic autopsy of victims of motorcycle accidents Artur Moskała ⇑, Krzysztof Woz´niak, Piotr Kluza, Karol Romaszko, Oleksij Lopatin Chair and Department of Forensic Medicine, Jagiellonian University Medical College, Grzegórzecka 16, 31-531 Kraków, Poland
a r t i c l e
i n f o
Article history: Received 14 November 2015 Received in revised form 22 November 2015 Accepted 23 November 2015 Available online 23 November 2015 Keywords: Forensic medicine Forensic autopsy Post-mortem computed tomography PMCT Motorcycle accidents
a b s t r a c t Since traffic accidents are an important problem in forensic medicine, there is a constant search for new solutions to help with an investigation process in such cases. In recent years there was a rapid development of post-mortem imaging techniques, especially post-mortem computed tomography (PMCT). In our work we concentrated on a potential advantage of PMCT in cases of motorcycle accident fatalities. The results of forensic autopsy were compared with combined results of the autopsy and PMCT to check in which areas use of these two techniques gives statistically important increase in number of findings. The hypothesis was confirmed in case of pneumothorax and fractures of skull, spine, clavicle, scapula, lower leg bones. As for majority of other bone fractures locations and brain injures there were single cases with pathologies visible only in PMCT, but too few to reach expected level of p-value. In case of injuries of solid organs and soft tissues statistical analysis did not confirmed any advantage of unenhanced PMCT use. On the whole it has been shown that PMCT used as an adjunct to forensic autopsy can cause an increase in information about vitally important regions in case of motorcycle accident fatalities. Ó 2015 Elsevier Ireland Ltd. All rights reserved.
1. Introduction According to the statistics published by the Polish Police Headquarters, the number of victims of traffic accidents involving motorcycles in recent years has remained more or less stable, with a slight downward trend. In the period covered by this publication, the figure was more than 200 deaths per year [1]. In each case of traffic accident it is not only necessary to determine the cause of death, but it is also required to describe in detail all the injuries, both external and internal in a very wide range. This is essential for further proper reconstruction of the course of events. Therefore, all the time forensic medicine seeks new methods that can improve the accuracy of reporting findings, as well as to improve its understanding to the non-professionals [2,3]. In this context, the importance of post-mortem imaging application in forensic medicine has been growing in recent years [4,5]. This especially applies to computed tomography, mainly due to easier access to CT scanners. Detailed analysis of the extent of how this technique complements the conventional autopsy in cases of traffic accident victims will allow to determine in what aspects its usefulness is of utmost importance. ⇑ Corresponding author. E-mail address: [email protected] (A. Moskała). http://dx.doi.org/10.1016/j.legalmed.2015.11.005 1344-6223/Ó 2015 Elsevier Ireland Ltd. All rights reserved.
The aim of the study was to compare the results of a conventional autopsy in cases of deaths of motorcycle riders to the results of the PMCT and to specify those areas where there were significant differences between the PMCT accuracy alone and this two techniques analyzed together. This would be the base to determine the extent to which PMCT examination is especially useful in the analysis of deaths of victims of motorcycle accidents. In future it can help to use this technique in a more targeted way, to increase as much as possible the accuracy of the whole post-mortem examination. 2. Material and methods We evaluated 48 cases of victims of motorcycle accidents that were autopsied in our Department of Forensic Medicine in the years 2012–2014. In every case conventional forensic autopsy and PMCT examinations were performed under an agreement with the prosecutor’s office as a standard forensic procedure, and our PMCT research program has been under surveillance of the relevant Bioethics Committee. The youngest victim was 7 y.o. and the oldest was 58 y.o. Out of the analyzed cases, 43 were males and 5 were females. The post mortem interval, between death and autopsy, was between 1 and 3 days. In each case an autopsy was preceded by a PMCT examination with Siemens Somatom
26
A. Moskała et al. / Legal Medicine 18 (2016) 25–30
only during PCMT examination. And in the third part these cases where injuries detected in both techniques are shown. For each number of cases a specified percentage was given, in relation to the whole number of cases with a concrete injury stated in the first column. The last column shows the calculated p-value. If a fluid was present in a body cavity, its attenuation coefficient was measured. In all cases results were above 50 Hounsfield units, which allowed to classify it as blood [6]. Later on presence of blood was confirmed during the autopsy.
Emotion 16 CT scanner. The scan parameters were: 130 kV, 240 mAs, collimation 16 0.6, pitch 0.85. The study covered the entire body in three series: the first from the top of the head to the shoulders, the second from the neck, above the shoulders (present in the previous series) to the height of the pubic symphysis and the third series covered the pelvis and lower limbs. The slice thickness was set to 0.75 mm for the head series and as for the trunk and lower extremities, it was set to 1.5 mm. For each range reconstructions were performed in the soft tissue and bone window (kernel H31s and H70s), as well as the pulmonary window for the thorax (kernel B70s). The results of the study were evaluated with the OsiriX software v.5.5.1 (Pixmeo SARL, Switzerland). The autopsy was carried out in each case by a physician with a speciality in the field of forensic medicine. PMCT (MPR, 3D reconstructions) results were confronted with the results of the autopsy by two board certified specialists in forensic medicine with longterm experience in PMCT interpretation (since 2009). We assessed the compliance of internal injuries in the area of the head, neck, chest, abdomen, pelvis and the extremities. The evaluation covered analysis of bone structures, soft tissues, presence of liquids and gases in the body cavities and pathological spaces. We compared the frequency of occurrence of injured structures in the abovementioned areas. In the statistical analysis we used the McNemar’s test, to verify following hypotheses:
3.1. Injuries of bone structures Table 1 presents a summary of bone injuries. Skull fractures were found in 67% of cases. More fractures were localized with PMCT in craniofacial area and at a cranial base. The circular fracture of the base of the skull draws particular attention, as this kind of injury is not always easy to locate during an autopsy, while it is clearly visible on 3D reconstructions (Fig. 1). In some cases, it was not a complete circle but a fracture beginning in the form of a hinge within the sphenoid bone and pyramids of temporal bones, extending towards the rear but not closing the circle. In 5 cases, fracture of condyles of the occipital bone was found on PMCT reconstructions. In a standard autopsy this may be much more difficult to verify because of the complicated access to the region of the skull base. The autopsy revealed more fractures within the base of the skull, especially in the anterior cranial fossa, where the thin bones hampered the assessment of post-traumatic changes in the PMCT examination. In general a statistically significant difference was found, indicating that a bigger number of skull fractures was detected by the combination of the two techniques (Fig. 2). As for the trunk, rib fractures were the most common bone injuries which occurred in 81.2% of cases. It should be noted that the overall percentage of incidence of fractures of the ribs exceeds 100%. This is due to the fact that in some cases different fractures were reported at the same time only by autopsy or only by PMCT. For this reason, we did not set the p-value for this group of injuries. The cases where more rib fractures were found during autopsy consisted mainly of fractures in the front lines and next to sternum. While the cases where more injuries were visible in the CT were related to fracture in posterior lines and next to the spine [7]. Spine fractures occurred in 68.8% of cases. Injuries visible only during autopsy were located at the level of the intervertebral discs,
H0 – use of post-mortem CT does not significantly increase the total number of findings in relation to the results of the autopsy alone. H1 – use of post-mortem CT does significantly increase the total number of findings in relation to the results of the autopsy alone. The level of significance was set at p < 0.05. Calculations were performed using Statistica (StatSoft, USA) v.12.5 software. 3. Results The results are presented in tables. The first column shows the total number of cases with given post-traumatic change and the percentage of the total number of cases. In subsequent columns we present number of cases where the injury was found only during autopsy, followed by number of cases with injuries found
Table 1 Bone injuries.
Skull Spine (without sacral bone) Ribs Sternum Clavicle Scapula Humerus Forearm bones Pubic bones Ischium bones Sacrum bone Iliac bones Sacroiliac joints Pubic symphysis Femurs Lower leg bones
I
II
Cases with injury n = 48 (%)
Injury distributions
III
IV
V
VI
VII
VIII
Cases with injury detected only during autopsy
Cases with injury detected only during autopsy (%)
Cases with injury detected only during PMCT
Cases with injury detected only during PMCT (%)
Cases with injury detected with both techniques
Cases with injury detected with both techniques (%)
p-value
32 (67.0) 33 (68.8) 39 (81.2) 16 (33.3) 15 (31.3) 15 (31.3) 12 (25.0) 15 (31.3) 12 (25.0) 4 (8.3) 4 (8.3) 5 (10.4) 8 (16.7) 7 (14.6) 15 (31.3) 22 (45.8)
3 7 18 8 0 0 3 3 0 0 0 0 1 1 0 0
9.4 21.2 46.2 50.0 0 0 25.0 20.0 0 0 0 0 12.5 14.3 0 0
12 22 19 1 8 13 0 5 5 2 2 0 1 1 3 10
37.5 66.7 48.8 6.3 53.3 86.7 0 33.3 41.7 50 50 0 12.5 14.3 20 45.5
17 4 7 7 7 2 9 7 7 2 2 5 6 5 12 12
53.1 12.1 17.9 43.7 46.7 13.3 75.0 46.7 58.3 50 50 100 75 71.4 80 54.5
0.02
