Quick assessment of gunshot wounds: A practical approach.

Transcription

1 Quick assessment of gunshot wounds: A practical approach. Poster No.: C-1538 Congress: ECR 2016 Type: Educational Exhibit Authors: M. Paniagua González, C. Fernández Álvarez, M. Urizar Gorosarri, J. M. Jiménez, D. D. J. De la Rosa Porras ; 1 2 MADRID, MA/ES, Madrid/ES Keywords: Trauma, Hemorrhage, Foreign bodies, Diagnostic procedure, CT, Conventional radiography, Emergency DOI: /ecr2016/C-1538 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 44

2 Learning objectives To explain the role of the radiologist in the urgent evaluation and treatment of patients with gunshot wounds, and to illustrate the more frequent injuries and findings in the MDCT studies performed in this context. Background In Spain, as well as in the vast majority of European countries, the current legislation does not allow civilian citizens to possess firearms, with the exception of those citizens possessing a hunting license. Therefore, the number of injuries caused by firearms is relatively low, as well as the number of medical publications about the subject. Of course, the number of cases is significantly much lower than in the USA, a country usually perceived as the reference in this area. Page 2 of 44

3 Fig. 1 References: A: 2011 Global Study on Homicide: Homicide by Firearms. B: WHO report on violence and health, The pathological effects of the gunshot wounds are very high, due to the quantity of kinetic energy transferred after the projectile exits the firearm. That energy is largely kept after it impacts the body. Besides, encased (jacketed) bullets used in higher velocity firearms tend to deform on impact, so they decelerate faster, hence increasing local tissue damage. Patients with firearm wounds are usually admitted to the Emergency Room (ER) after they are transported by the Emergency Response Teams, or paramedics, since they are usually clinically unstable. The evaluation and treatment of these patients requires the synchronized cooperation of several physicians; an MDCT is required in almost all cases. Page 3 of 44

4 Images for this section: Fig. 1 A: 2011 Global Study on Homicide: Homicide by Firearms. B: WHO report on violence and health, Page 4 of 44

5 Findings and procedure details We present a review of more than 150 cases of patients who were admitted to the ER of our hospital after suffering gunshot wounds. The patients were assessed via cranial, neck, chest and/or abdominal CT, depending on the presumed affected area. The main role of the radiologist in these cases is to determine the place of the entry wound, as well as the path of the projectile. The radiologist also assesses the full extent of the damage to the organs affected and the severity of the injuries, so both the medical and trauma surgical teams can establish the proper priorities in the treatment of the patient. The US-FAST, frequently used in stabbed patients, is not accurate enough in these situations, in which CT is essential. In stab wounds, a fast physical examination allows the physicians to identify the point of entry and assess which organs have most likely been affected. If there is no time to perform a CT, the patient will be taken to the operating room immediately. In these cases, the radiologist will only perform an US-FAST to determine the presence and extent of hemopericardium and hemoperitoneum. Conversely, in cases of patients with gunshot wounds, it is not possible to determine the path of the projectile by only performing a physical examination and identifying the entry wound. As we will see later, the projectile can strike a solid structure and follow unpredictable paths, potentially affecting several organs. Therefore, it is of critical importance to perform an MDCT. The protocol used in our hospital is as follows: Simple cranial CT (as well as orbital / facial CT if damages at that level are suspected). Simple cervical spine CT or neck CT with contrast, if cervical wounds are suspected. Vascular arterial phase chest and superior abdomen CT. An additional CT of the whole abdomen-pelvic areas may be performed if active intra-abdominal haemorrhage is suspected. Vascular portal venous phase abdomen-pelvic CT. Excretory urinary phase pelvic CT, if vesical rupture is suspected. TRAJECTORY AND LOCALIZATION OF THE PROJECTILE Page 5 of 44

6 The vast majority of the projectiles are of metallic nature. Therefore, the preferred methods to detect them are X-Rays and MDCT, since the high attenuation of the bullets allows an easy identification and differentiation from the tissues adjacent to them. (Fig. 2 on page 20) In case of X-Rays, it is essential to have two projections (postero-anterior and lateral), in order to determine if the bullet is placed inside the thorax /abdominal cavity or in any of its walls. Fig. 3: Notice that in postero-anterior projection it is not possible to assess if the bullet is inside the thorax or in the wall (like the pacemaker device in this patient). We need the lateral projection to determine both locations. References: - MADRID/ES The MDCT is the "gold standard" technique used both to ensure the localization of the projectile and to evaluate the potential damage made to the internal organs of the patient. The high density of the bullet produces the beam hardening artefact, which can be manually corrected by modifying the window-visualization settings (Fig. 4 on page 21). Page 6 of 44

7 Furthermore, MDCT allows to properly evaluating the presence of several projectiles inside the same patient, in case that its presence might have been overlooked by the Emergency Services (Fig. 5 on page 23). MDCT also allows to properly determine the entry wound, as a solution of continuity of the skin that is followed by a haematic path -more or less linear-, as well as to identify the exit site (if it exists) (Fig. 6 on page 23 and Fig. 7 on page 24). Fig. 7: A: Brain-window cranial CT, showing a linear haemorrhagic path from the right parietal lobe to the left temporal lobe, as well as subarachnoid hemorrhage and intraventricular bleeding. B: Bone-window, showing the entry site at the right parietal bone and the projectile, on the left side some slices below. References: - MADRID/ES The path of the projectile can also be predicted by the presence of gas, bone or metallic fragments (if the projectile has fragmented) in a linear distribution (Fig. 8 on page 24, Fig. 9 on page 25 and Fig. 10 on page 27). Page 7 of 44

8 But even if the entry wound and the bullet path have been correctly identified, the projectile can show a significant deviation. This yaw corresponds to a significant distortion in the projectile path, due to its impact against high density internal structures, most frequently bones. A proper and careful evaluation of the organs located between the bullet and the entry wound must be made. Furthermore, we have to make sure that not only those organs which are apparently damaged in the course of the haemorrhagic path are evaluated (Fig. 11 on page 27 and Fig. 12 on page 28). Page 8 of 44

9 Page 9 of 44

10 Fig. 12: Same patient shown in Fig 11. In the sagittal MPR reconstruction we can see again the entry wound (arrow) and the reason why the bullet was deviated: it impacted against a rib (asterisk). Fortunately, no internal organ was damaged this time. References: - MADRID/ES ORGANIC DAMAGE As it frequently happens with politraumatized patients, the condition of patients who have suffered gunshot wounds is usually critical. Therefore, prompt patient stabilization and surgery is essential. The severity of the situation requires a quick and accurate CT assessment by the radiologist, who may verbally inform to medical and surgical services about the findings. Therefore, we must have a clear understanding of the injuries that are most likely going to be found. A strict order of priorities must be established for the exploration of the different anatomic areas, so we can obtain a faster visualization of the study. As we indicated before, the accurate identification of the entry wound and the projectile path will help us to determine which organs are probably damaged, so these ones should be analysed first. Nevertheless, the bullet can describe different paths after impacting the different bone structures, so we must also evaluate the organs that are apparently not affected. In these cases, it is very useful to look for sentinel hematomas, because it could mean that an adjacent organ is bleeding. The presence of metallic fragments of the projectile can mislead our assessment, because their high density is very similar to the density of the blood in the arterial phase. In order not to confuse those fragments with the presence of points of active bleeding, we must carefully compare the arterial phase with the venous phase, so we can evaluate if there is a significant increase of the hyperdense image. If that is the case, it may be a clear indication that active bleeding exists, and that the bleeding is actively progressing. Page 10 of 44

11 Fig. 13: : A: Pellets in pelvis, showing a high density, very similar to the aorta in the arterial phase. B: Notice they do not show any significant modifications in the venous phase. C: Milimetric hyperdense images inside a liver laceration, again similar to aorta in the arterial phase; it is not clear if they correspond to hemorrhage or to bullet fragments. D: In the venous phase they increase their number and size, confirming the existence of active bleeding; the absence of beam hardening artefact can also help to assess the difference between pellets / bullet fragments and active bleeding. References: - MADRID/ES The ideal situation would be to have a previous simple phase, but, normally, we will only perform it when we suspect that multiple metallic fragments could exist inside the patient (for example, if the gun shot has been caused by gun pellets). These are the main injuries that we must look for in patients with gunshot wounds: Page 11 of 44

12 CRANIUM Hemorrhage: depending on the progress of the projectile inside the patient's skull, we can find a full range of bleeding: Subgaleal contusion Epidural hematoma Subdural hematoma Subarachnoid hemorrhage +/- intraventricular bleeding Intraparenchymatouse hemorrhage (typically of linear morphology following the bullet path) Signs of intracranial hyperpressure: disappearance of grooves, ventricular collapse, deviation of the middle line, brain parenchymal herniation Pneumoencephalus: as in the intraparenchymatouse hemorrhage, it usually follows the linear path of the projectile. Bone fractures: usually resulting in burst of the bone, comminuted. (Fig. 7 Fig. 8 Fig. 14 Fig. 15 Fig. 16) Page 12 of 44

13 Fig. 14: Patient showing typical intra-cranial injuries secondary to gunshot traumatism: Subgaleal contusion, subdural hematomas, subarachnoid haemorrhage, Intraparenchymatouse haemorrhage, pneumoencephalus, middle line deviation (as a sign of intracranial hypertension) and comminuted fractures of the left frontal bone. Hyperdense bullet fragments can also be seen, at the right frontal lobe. References: - MADRID/ES HEAD AND NECK Soft tissue hemorrhage: points of active bleeding must be looked for, and, if there is any doubt, a second phase must be performed in order to compare and assess if there is progressive bleeding. Hemosinus: the presence of blood inside any of the paranasal sinuses is usually a clear indicator of bone fractures, not yet detected. Bone fractures: they are usually very complex and comminuted. Therefore, multiplanar and volumetric reconstructions will be very useful for the maxillofacial surgeon in order to adequately plan the reconstructive surgery. Page 13 of 44

14 Emphysema: can be subcutaneous or between the muscle planes. It is usually originated at the site of the entry wound, but if there is a concentration of gas bubbles next to the airways or to the esophageal-pharyngeal areas, we must carefully evaluate the adjacent structures to rule out any possible associated lesions. (Fig. 17 on page 33 and Fig. 18 on page 34) Fig. 18: Projectile path between left orbit and left hemimandible, through the left maxilla, associated with left maxillar hemosinus. Notice the concentration of gas bubbles in the oro-pharyngeal pathway, as a result of lesion at this location. References: - MADRID/ES Page 14 of 44

15 SPINE Bone fractures: they are usually not subtle fractures. They are most frequently comminuted or burst fractures, that can be easily detected by following the path of the projectile from the entry wound, since the bullet generally does not show any sign of deviation until it impacts a bone structure; most commonly, a vertebral body. Medullary canal compromise: as in any other spine trauma, what is most important is to asses if the spine cord remains intact, more than the fracture itself. The best tool to evaluate if medullary canal compromise exists is the MPR-sagittal reconstruction. If there is any doubt or a medullar lesion is suspected, the best procedure is to perform an urgent MRI study of the spine. Dural sac hematomas: if vertebral fractures or paravertebral hematomas are detected, even if the vertebral bodies show a proper alignment and the medullar canal is not apparently compromised, we must force the window of visualization of the study, in order to detect hematomas of the dural sac, which could be associated with significant medullar damage. (Fig. 19 on page 35, Fig. 20 on page 36 and Fig. 21 on page 37) Fig. 21: Bullet impacted against the C4 vertebral body, showing comminuted fractures. In the sagittal MPR reconstruction there is a clear displacement of the posterior wall of the vertebra, compromising the medullar canal. References: - MADRID/ES Page 15 of 44

16 THORAX Pneumothorax: It is very important to assess the extent of the pneumothorax, and also to confirm if it is indeed a tension pneumothorax. These factors should determine the urgency of inserting a chest drain. As opposed to the closed traumas, in which the presence of pneumothorax reflects, almost unequivocally, the existence of one or several ipsilateral rib fractures, in patients who have suffered gunshot wounds, the projectile can travel from one hemithorax to the other, thus causing a pneumothorax in both. The fact that the pneumothorax is larger in one side does not necessarily imply that the bullet has landed in that hemithorax. In order to identify the entry wound, it is much more reliable to look for a hematoma in the thoracic wall, or for rib fractures (Fig. 22 on page 38). Pulmonary contusions or lacerations: usually this lesions are very evident, thanks to the different densities between blood and pulmonary parenchyma. But if we are not able to visualize them at first, we must suspect that they exist when there is an ipsi- or contralateral hemothorax or pneumothorax. The AAST scale (American Association for the Surgery of Trauma) allows grading its severity. Hemothorax: as it is the case with the pneumothorax, we must inform the surgeon about the amount of bleeding, so he can determine the urgency in the insertion of a drainage tube. Cardiac lesions: although less frequent than the pulmonary lesions, the cardiac lesions are potentially much more severe and they are usually associated with hemopericardium. Therefore, if we find pericardial effusion in this context, we must determine the values of attenuation to confirm if it presents a hemorrhagic component. Aortic lesion: these are also extremely severe lesions. Therefore, we must perform a radiologic evaluation of the aorta, looking specifically for adjacent active points of bleeding and/or pseudoaneurysms. Esophageal or tracheal lesions: as mentioned before, the presence of gas bubbles or hematomas in the mediastinum allows us to suspect the existence of these type of lesions. Rib fractures: they can be single or multiple, depending on the angle of impact of the bullet against the thorax. As we have explained before, the existence of fractures in one single hemithorax does not implicate that the presence of additional lesions in the contralateral lung can be disregarded. (Fig. 23 on page 39 and Fig. 24 on page 39) Page 16 of 44

17 Fig. 24: Linear haemorrhagic path in the left lung (A), associated with intra-alveolar bleeding, seen as adjacent ground-glass opacities (B). Bone window (C) allows a better visualization of the projectile. References: - MADRID/ES ABDOMEN Solid abdominal viscera contusions or lacerations: The severity of these lesions can also be graded by using the AAST scales. Bowel lesions: The presence of gas bubbles inside the peritoneal cavity or inside the mediastine can be explained by the entrance of the bullet from outside. However, if the bubbles show a specific area of concentration, it is advisable to carefully evaluate the adjacent intestinal structures to assess if a lesion exists. Diaphragmatic ruptures: These types of ruptures can be frequently overlooked at the axial planes. Therefore, it is advisable to use coronal or sagittal reconstructions, that will allow us to visualize the diaphragm perpendicularly, in order to evaluate its full integrity. Vascular lesions: It is particularly important to discard the presence of arterial lesions. Therefore, apart from the searching for sentinel hematomas, we must also look for points of active bleeding and/or pseudoaneurysms. The Maximum Intensity Projection (MIP) reconstructions are a very powerful tool for this purpose. Hemoperitoneum: as it happens with the thorax, the presence of free bleeding indirectly reflects vascular or solid organ lesions, and those lesions must be identified. If the amount of hemoperitoneum is important, it will be necessary to use drainage tubes. Page 17 of 44

18 Vesical rupture: although less frequent than in closed traumas, a vesical rupture implies a higher risk of mortality. If we suspect the existence of a vesical rupture, we must acquire an urography phase 6-7 minutes after the start of the study, in order to obtain an adequate vesical repletion and to be able to detect any possible contrast extravasation. (Fig. 25 on page 40 and Fig. 26 on page 42) Fig. 26: Another example of abdominal gunshot, showing both liver and right kidney lacerations, as well as hemoperitoneum at the right flank. References: - MADRID/ES LIMBS Page 18 of 44

19 If the projectile has simply impacted against a limb, an MDCT is usually not necessary, unless the single X-Ray shows a complex bone fracture. In that particular case, again, the multiplanar and volumetric reconstructions will be very useful to help the orthopaedic surgeon to better plan the surgery procedure. Fig. 27: Complex comminuted ulnar fracture, secondary to gunshot. The displacement of the fracture, as well as the presence of bullet fragments, made it necessary to perform a MDCT, in order to plan the surgery. References: - MADRID/ES Page 19 of 44

20 Images for this section: Fig. 2: High density foreign bodies (arrows) in X-rays (A) and CT (B), corresponding to bullets. C: Multiple foreign bodies in pelvis (pellets in this case). Page 20 of 44

21 Fig. 3: Notice that in postero-anterior projection it is not possible to assess if the bullet is inside the thorax or in the wall (like the pacemaker device in this patient). We need the lateral projection to determine both locations. Page 21 of 44

22 Page 22 of 44

23 Fig. 4: A: Abdominal-window CT. Bullet in the pararenal fat, causing beam hardening artefact. B: Modifying the window-visualization settings (almost to bone-window), the artefact is partially corrected. Fig. 5: Patient showing two projectiles, located in left shoulder and left paraspinal musculature. Page 23 of 44

24 Fig. 6: Entry wound at the skin of the right flank, followed by a linear haemorrhagic path with air bubbles in the subjacent fat. There is no exit site, since the projectile stopped at the contralateral lumbar fat. Fig. 7: A: Brain-window cranial CT, showing a linear haemorrhagic path from the right parietal lobe to the left temporal lobe, as well as subarachnoid hemorrhage and intraventricular bleeding. B: Bone-window, showing the entry site at the right parietal bone and the projectile, on the left side some slices below. Page 24 of 44

25 Fig. 8: A: Haemorrhagic path with multiple metallic foreign bodies (since the bullet was partially fragmented). B: In this case both entry and exit sites are seen at the frontal bones. Page 25 of 44

26 Page 26 of 44

27 Fig. 9: Projectile tract through the orbits, with multiple comminuted fractures. Fig. 10: Bullet path with multiple metallic fragments in the lumbar paraspinal musculature. Page 27 of 44

28 Fig. 11: In this patient there is a considerable distance between the entry wound (arrow) at the skin of the left flank (middle-kidneys level), and the location of the bullet, in the pelvis, several slices below. The path of the projectile is determined by the presence of air bubbles in the anterior abdominal wall (Continues in Fig 12). Page 28 of 44

29 Page 29 of 44

30 Fig. 12: Same patient shown in Fig 11. In the sagittal MPR reconstruction we can see again the entry wound (arrow) and the reason why the bullet was deviated: it impacted against a rib (asterisk). Fortunately, no internal organ was damaged this time. Fig. 13: : A: Pellets in pelvis, showing a high density, very similar to the aorta in the arterial phase. B: Notice they do not show any significant modifications in the venous phase. C: Milimetric hyperdense images inside a liver laceration, again similar to aorta in the arterial phase; it is not clear if they correspond to hemorrhage or to bullet fragments. D: In the venous phase they increase their number and size, confirming the existence of active bleeding; the absence of beam hardening artefact can also help to assess the difference between pellets / bullet fragments and active bleeding. Page 30 of 44

31 Fig. 14: Patient showing typical intra-cranial injuries secondary to gunshot traumatism: Subgaleal contusion, subdural hematomas, subarachnoid haemorrhage, Intraparenchymatouse haemorrhage, pneumoencephalus, middle line deviation (as a sign of intracranial hypertension) and comminuted fractures of the left frontal bone. Hyperdense bullet fragments can also be seen, at the right frontal lobe. Page 31 of 44

32 Fig. 15: Linear haemorrhagic path between right frontal lobe and left parietal lobe, associated with subdural hematomas, intraventricular bleeding, pneumoencephalus, and burst right frontal bone fracture. The bullet was deviated after impacting the left parietal bone. Page 32 of 44

33 Fig. 16: Another example of cranial gunshot, with entry and exit sites at right parietal and left occipital bones, respectively. Linear haemorrhagic path can been at the posterior fossa, as well as subdural tentorial hematoma and intraventricular bleeding. Page 33 of 44

34 Fig. 17: Right infra-orbital gunshot, associated with soft tissue haemorrhage, emphysema, and right maxillar hemosinus (as a result of anterior wall fracture). Page 34 of 44

35 Fig. 18: Projectile path between left orbit and left hemimandible, through the left maxilla, associated with left maxillar hemosinus. Notice the concentration of gas bubbles in the oro-pharyngeal pathway, as a result of lesion at this location. Page 35 of 44

36 Fig. 19: Bullet impacted against the C4 vertebral body. Despite the considerable soft tissue haemorrhage and emphysema, there is no bone fractures, nor medullary canal compromise. The hyperdense image at the C4 medullar level is caused by the beam hardening artefact of the projectile, and should not be misinterpreted as intramedullary haemorrhage. Page 36 of 44

37 Fig. 20: Bullet impacted against L4-L5 vertebral bodies. The projectile reaches the medullary canal, which could indeed be compromised in this case. Page 37 of 44

38 Fig. 21: Bullet impacted against the C4 vertebral body, showing comminuted fractures. In the sagittal MPR reconstruction there is a clear displacement of the posterior wall of the vertebra, compromising the medullar canal. Fig. 22: Thoracic gunshot, associated with bilateral hemothorax. The bullet is seen in the left hemithorax, despite the pneumothorax is larger at the right side, which means the bullet travelled from one hemithorax to the other. Page 38 of 44

39 Fig. 23: Another example of thoracic gunshot, showing right lung contusion, associated with hemothorax and small pneumothorax. Multiple rib fractures are seen in the MIP and MPR reconstructions, showing the linear path of the projectile. Page 39 of 44

40 Fig. 24: Linear haemorrhagic path in the left lung (A), associated with intra-alveolar bleeding, seen as adjacent ground-glass opacities (B). Bone window (C) allows a better visualization of the projectile. Page 40 of 44

41 Page 41 of 44

42 Fig. 25: Same patient shown in Fig 13 C-D. Abdominal gunshot, showing liver laceration, associated with active bleeding and air bubbles. Fig. 26: Another example of abdominal gunshot, showing both liver and right kidney lacerations, as well as hemoperitoneum at the right flank. Page 42 of 44

43 Fig. 27: Complex comminuted ulnar fracture, secondary to gunshot. The displacement of the fracture, as well as the presence of bullet fragments, made it necessary to perform a MDCT, in order to plan the surgery. Page 43 of 44

44 Conclusion The life of patients with gunshot wounds depends, in many cases, on a quick diagnosis and treatment. The best tool to achieve a fast and reliable diagnosis is a prompt MDCT performance, as well as the cooperation of multidisciplinary teams of properly trained radiologists, surgeons and physicians. Personal information References Wilson AJ. Gunshot injuries: what does a radiologist need to know?. Radiographics Sep-Oct;19(5): Folio LR et al. CT-based ballistic wound path identification and trajectory analysis in anatomic ballistic phantoms. Radiology Mar;258(3): Levy AD et al. Virtual autopsy: preliminary experience in high-velocity gunshot wound victims. Radiology Aug;240(2): Múnera F et al. Gunshot wounds of abdomen: evaluation of stable patients with triple-contrast helical CT. Radiology May;231(2): Folio LR et al. Blast and ballistic trajectories in combat casualties: a preliminary analysis using a cartesian positioning system with MDCT. AJR Am J Roentgenol Aug;197(2):W Hacking C. and Dr Stanislavsky A. et al. - Imaging of gun shot injuriesradiopaedia.com Nemzek WR. Prediction of major vascular injury in patients with gunshot wounds to the neck. AJNR Am J Neuroradiol Jan;17(1): Page 44 of 44