DOI: 10.1148/rg.244035035
RadioGraphics 2004;24:1087-1098
© RSNA, 2004
Vascular Injuries of the Neck and Thoracic Inlet: Helical CT–Angiographic Correlation1
Diego B. Núñez, Jr, MD, MPH,
Mario Torres-León, MD and
Felipe Múnera, MD
1 From the Department of Radiology, Hospital of Saint Raphael, Yale University School of Medicine, 1450 Chapel St, New Haven, CT 06511 (D.B.N., M.T.L.); and the Department of Radiology, Jackson Memorial Hospital, University of Miami School of Medicine, Miami, Fla (F.M.). Presented as an education exhibit at the 2002 RSNA scientific assembly. Received February 19, 2003; revision requested April 8; final revision received September 11; accepted September 12. All authors have no financial relationships to disclose. Address correspondence to D.B.N. (e-mail: dnunez@srhs.org).
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Abstract
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Imaging evaluation of patients suspected to have arterial injuries of the neck has traditionally been performed by using conventional angiography as an alternative to surgical exploration. However, there has been recent interest in and growing experience with use of noninvasive imaging techniques for the assessment of vascular injuries. Contrast material–enhanced helical computed tomographic (CT) angiography is increasingly being used to evaluate trauma patients in stable condition who are at risk for vascular injuries. It allows characterization of traumatic vascular lesions in the neck such as partial or complete occlusion, pseudoaneurysm, intimal flap, dissection, and arteriovenous fistula. In the same setting, CT angiography provides valuable additional information about the cervical soft tissues, aerodigestive tract, spinal canal, and spinal cord. In cases of penetrating gunshot injuries, the trajectory of the bullet and the locations of fragments can be assessed. CT angiography may be limited by artifacts from metallic fragments and occasionally by abundant soft-tissue air or streak artifacts in the shoulders. In such cases, conventional angiography is necessary for optimal assessment of vascular injuries. CT angiography can be used as a noninvasive alternative to conventional angiography in patients suspected to have vascular injuries but without initial indications for surgical treatment.
© RSNA, 2004
Index Terms: Carotid arteries, injuries, 1722.40, 90.40, 90.70 • Computed tomography (CT), angiography, 1722.12116, 90.12916 • Neck, injuries, 1722.40, 90.40, 90.70 • Vertebral arteries, injuries, 901.40, 901.70
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LEARNING OBJECTIVES
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After reading this article and taking the test, the reader will be able to:
- Identify the CT angiographic appearances of different vascular injuries of the neck.
- Discuss the relative merits of CT angiography in initial assessment of patients suspected to have vascular trauma of the neck.
- Describe the technical parameters for performing CT angiography and the common pitfalls that limit the diagnostic information.
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Introduction
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Penetrating and blunt injuries to the neck and thoracic inlet can have significant morbidity and mortality. Cervical vascular injuries occur more commonly after penetrating trauma, and approximately 25% of penetrating neck injuries result in a vascular injury (1). Among vascular injuries resulting from this mechanism, the carotid arteries are more frequently involved (80%) (2). These lesions may lead to stroke in 15% of patients and are associated with a mortality rate of up to 22% (3–5). The vertebral arteries are injured in 43% of cases with penetrating trauma. Conversely, in blunt trauma, vertebral artery injuries are more common than carotid injuries, and they do not manifest clinically as carotid injuries do (6,7). Frequently, there is a lack of signs and symptoms, and only occasionally they may present as a vertebrobasilar stroke or as an enlarging arteriovenous fistula (8,9).
Surgical management is challenging due to the anatomic complexity and difficult access to vascular structures, particularly near the skull base and in the thoracic inlet (1,10–12). These factors contribute to an ongoing effort to establish the most appropriate diagnostic strategy (13–19) and to determine the role of imaging in the initial patient assessment.
Both angiography and noninvasive techniques have been proposed to evaluate these injuries in patients who do not require immediate surgical treatment. Angiography has been traditionally accepted as the standard of reference; although it is regarded as a relatively safe examination, serious neurologic complications can result. As an invasive procedure, the routine use of angiography in patients with penetrating cervical injuries has also been challenged because of the high number of negative examinations (15,16). Color Doppler ultrasonography (US) has been used as a noninvasive test to assess penetrating injuries of the neck and was proved sensitive for assessment of stable patients with zone II injuries (18). However, the usefulness of color Doppler US is limited in patients with subcutaneous air or large hematomas, which are frequently associated with penetrating trauma. In addition, it is operator dependent and may be more time-consuming than desirable in the acute care setting. Magnetic resonance (MR) imaging has also been proposed for assessment of vascular injuries and particularly for the diagnosis of posttraumatic dissection (19), but it may be limited for depiction of concurrent osseous injuries. Furthermore, MR is not well suited for imaging acutely injured patients requiring life support devices, which may not be compatible with the magnet. In recent years, computed tomography (CT) has been made increasingly available in the emergency setting. The development of helical CT scanners with a multi–detector row configuration and three-dimensional postprocessing has further encouraged the use of CT angiography in the evaluation of suspected vascular injury of the neck. High-quality axial images and reformatted angiographic displays can be obtained in a shorter time than with other modalities and with a lesser complication rate than catheter angiography.
The purpose of this article is to illustrate selected cases of cervical and thoracic inlet vascular injuries that were diagnosed with CT angiography and corroborated with catheter angiography. Specific topics discussed are mechanisms of vascular trauma, technique, types of vascular lesions, and pitfalls.
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Mechanisms of Vascular Trauma
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Blunt Trauma
The effects of blunt trauma are very tissue specific, and the degree of injury is intimately related to the elasticity and cohesiveness of the affected organ or anatomic region, which determine its ability to withstand stretching or compression. Overall, blunt trauma to the neck has a low rate of associated vascular injuries (0.67%), and this has justified the tendency toward a more conservative approach and the use of noninvasive techniques in this patient population (20–25). Using more liberal criteria that include routine catheter angiography, some authors have found a 1.11% rate of carotid injuries and a 0.77% rate of vertebral artery injuries (21).
Penetrating Trauma
Most penetrating injuries are caused by gunshot wounds and sharp objects. With this type of mechanism, the affected tissues are crushed by the penetrating object and typically do not survive the trauma. Despite the potential for significant tissue destruction and the relatively closed anatomic relationships of the neck, the rate of vascular injury can be considered lower than one would anticipate. It has been estimated that 25% of patients with this type of injury have some form of vascular involvement (1,26). This is partially related to the fact that most gunshot injuries are produced by relatively low-velocity bullets, in addition to the concept that most vascular injuries are determined by direct contact with the bullet or its fragments (27,28). Therefore, assessment of trajectory and proximity is an additional important contribution of cross-sectional imaging with CT.
Penetrating wounds to the neck are divided into three zones following specific anatomic landmarks (Fig 1). This classification is used to differentiate the diagnostic approach according to the site of penetration. Surgical access to explore vascular structures is limited in zones I and III, and conventional angiography has been largely used in patients presenting with such injuries. Zone II injuries have been traditionally explored surgically, but this has been challenged by a more conservative approach that uses arteriography and, more recently, US and CT angiography.
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Figure 1. Zones of the neck for classification of penetrating injuries. Zone I extends from the sternal notch to the cricoid cartilage. The thoracic inlet may be considered an inferior extension of this zone. Zone II extends from the cricoid cartilage to the angle of the mandible. Zone III extends from the angle of the mandible to the base of the skull.
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CT Technique
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Vascular imaging has been significantly improved with the use of multi–detector row scanners. Our case material includes patients examined both with single detector row helical CT and more recently with scanners that have a multi–detector row configuration. We currently use a Somatom Volume Zoom scanner (Siemens Medical Systems, Iselin, NJ) with the ability to produce 0.5-mm-thick sections and a high-quality three-dimensional data set. For cervical CT angiography, we use a 3 x 1-mm collimator setting, and sections of 1-mm thickness are generated and reconstructed at 0.5-mm intervals. The resulting data set is transferred to a workstation for postprocessing and interpretation. We are currently using the Aquarius three-dimensional workstation software (TeraRecon, San Mateo, Calif). This software includes interactive volume rendering, slab multiple intensity projection, multiplanar reformation, shaded surface rendering, and editing. For interpretation, the radiologists initially use the set of axial source images followed by image viewing in additional planes to increase diagnostic confidence.
One hundred milliliters of nonionic contrast medium is automatically injected at 4 mL/sec through an 18-gauge catheter placed in an antecubital vein, and a scanning delay of 15 seconds is used. The caudocranial helical acquisition was planned on the basis of a lateral digital scout view of the neck, which starts at the top of the aortic arch and ends at the base of the skull. Scanning parameters common to all examinations were tube current of 250 mAs, tube potential of 120 kVp, and 20-cm field of view.
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Types of Vascular Lesions
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Regardless of the mechanism of injury, vascular lesions have similar imaging features, whether assessed by contrast material–enhanced cross-sectional imaging or catheter angiography. Vessel response to injury is limited to either partial wall damage or total wall disruption, and specific signs of arterial injury include occlusion, free or contained extravasation (pseudoaneurysm), intimal flap, dissection, and arteriovenous fistula.
Partial or Complete Occlusion
Partial or complete vessel occlusion is reported to be the most common carotid artery injury in both penetrating trauma (36%) (5) and blunt trauma (33%) (22). Occlusion is seen as lack of vessel enhancement at CT angiography. Vessel narrowing and marginal irregularities can be seen in traumatic stenosis due to intimal flaps or small hematoma of the vessel wall (Figs 2, 3).
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Figure 2a. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 2b. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 2c. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 2d. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 2e. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 2f. Partial occlusion in a patient with a gunshot wound to the left side of the neck (zones II and III). (a) Axial CT image obtained proximal to the bifurcation of the left common carotid artery (arrow) shows obliteration of the perivascular fat planes with displacement and narrowing of the adjacent left jugular vein (arrowhead). (b) Axial CT image obtained just above the bifurcation of the left common carotid artery shows normal calibers of the left internal carotid (IC) and left external carotid (EC) arteries and cephalic extension of the hematoma. (c) Axial CT image obtained cephalad to b shows narrowing and posterior irregularity of the left internal carotid artery (arrow), findings consistent with a vascular wall injury. (d-f) Slab maximum intensity projection image (d), surface rendered reformatted angiogram (e), and selective angiogram (f) of the left common carotid artery show the marginal vascular injury and the partial occlusion. In f, the levels of the CT images (a, b, and c) are shown as lines A, B, and C, respectively.
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Figure 3a. Total occlusion in a patient with a gunshot wound to zone II of the neck. (a) Axial CT image obtained above the bifurcation of the left common carotid artery shows a crescentic defect in the anterior aspect of the left internal carotid artery (arrow). (b) Axial CT image obtained cephalad to a shows absence of enhancement in the left internal carotid artery secondary to total occlusion (*) and compression of the adjacent left internal jugular vein (arrow). Note the normal caliber of the left external carotid artery (LEC) and the prevertebral subcutaneous emphysema, which indicates the trajectory of the bullet. (c) Digital subtraction angiogram shows the total occlusion of the left internal carotid artery (LIC). The levels of the CT images (a and b) are shown as lines A and B, respectively. Dashed line = expected location of the anterior vessel wall. (d) Slab maximum intensity projection image shows the abrupt cutoff of the left internal carotid artery (arrow), a finding consistent with occlusion.
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Figure 3b. Total occlusion in a patient with a gunshot wound to zone II of the neck. (a) Axial CT image obtained above the bifurcation of the left common carotid artery shows a crescentic defect in the anterior aspect of the left internal carotid artery (arrow). (b) Axial CT image obtained cephalad to a shows absence of enhancement in the left internal carotid artery secondary to total occlusion (*) and compression of the adjacent left internal jugular vein (arrow). Note the normal caliber of the left external carotid artery (LEC) and the prevertebral subcutaneous emphysema, which indicates the trajectory of the bullet. (c) Digital subtraction angiogram shows the total occlusion of the left internal carotid artery (LIC). The levels of the CT images (a and b) are shown as lines A and B, respectively. Dashed line = expected location of the anterior vessel wall. (d) Slab maximum intensity projection image shows the abrupt cutoff of the left internal carotid artery (arrow), a finding consistent with occlusion.
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Figure 3c. Total occlusion in a patient with a gunshot wound to zone II of the neck. (a) Axial CT image obtained above the bifurcation of the left common carotid artery shows a crescentic defect in the anterior aspect of the left internal carotid artery (arrow). (b) Axial CT image obtained cephalad to a shows absence of enhancement in the left internal carotid artery secondary to total occlusion (*) and compression of the adjacent left internal jugular vein (arrow). Note the normal caliber of the left external carotid artery (LEC) and the prevertebral subcutaneous emphysema, which indicates the trajectory of the bullet. (c) Digital subtraction angiogram shows the total occlusion of the left internal carotid artery (LIC). The levels of the CT images (a and b) are shown as lines A and B, respectively. Dashed line = expected location of the anterior vessel wall. (d) Slab maximum intensity projection image shows the abrupt cutoff of the left internal carotid artery (arrow), a finding consistent with occlusion.
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Figure 3d. Total occlusion in a patient with a gunshot wound to zone II of the neck. (a) Axial CT image obtained above the bifurcation of the left common carotid artery shows a crescentic defect in the anterior aspect of the left internal carotid artery (arrow). (b) Axial CT image obtained cephalad to a shows absence of enhancement in the left internal carotid artery secondary to total occlusion (*) and compression of the adjacent left internal jugular vein (arrow). Note the normal caliber of the left external carotid artery (LEC) and the prevertebral subcutaneous emphysema, which indicates the trajectory of the bullet. (c) Digital subtraction angiogram shows the total occlusion of the left internal carotid artery (LIC). The levels of the CT images (a and b) are shown as lines A and B, respectively. Dashed line = expected location of the anterior vessel wall. (d) Slab maximum intensity projection image shows the abrupt cutoff of the left internal carotid artery (arrow), a finding consistent with occlusion.
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Pseudoaneurysm
Pseudoaneurysm formation is the result of partial to complete disruption of the vascular wall, which ultimately leads to hemorrhage that is contained by the adventitia of the vessel wall or the perivascular soft tissues. It can also be regarded as a contained extravasation. On axial CT images, pseudoaneurysms are typically seen as an abnormal contrast material accumulation that appears at the time of arterial enhancement and is contiguous and eccentric to the vessel lumen. The differentiation from free or noncontained extravasation may be difficult, but management is not frequently affected by this distinction. Pseudoaneurysms are common injuries in penetrating trauma (Figs 4–9) and may account for up to one-third of lesions involving the internal carotid artery (11).
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Figure 4a. Pseudoaneurysm in a patient with a gunshot wound to the lower left side of the neck (zone I). (a) Digital subtraction angiogram shows a marginal defect in the proximal left subclavian artery (arrow). (b) Axial CT image, obtained at the level of the sternal manubrium 2 days after admission of the patient to the hospital, shows a small area of contained extravasated contrast material along the left lateral aspect of the left subclavian artery (arrow). The intimal defect seen in a has evolved into a small pseudoaneurysm. (c) Follow-up conventional angiogram shows the pseudoaneurysm. (d) Digital subtraction aortogram of the aortic arch, obtained after endovascular treatment with a Wallstent (Boston Scientific, Natick, Mass), shows occlusion of the lesion.
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Figure 4b. Pseudoaneurysm in a patient with a gunshot wound to the lower left side of the neck (zone I). (a) Digital subtraction angiogram shows a marginal defect in the proximal left subclavian artery (arrow). (b) Axial CT image, obtained at the level of the sternal manubrium 2 days after admission of the patient to the hospital, shows a small area of contained extravasated contrast material along the left lateral aspect of the left subclavian artery (arrow). The intimal defect seen in a has evolved into a small pseudoaneurysm. (c) Follow-up conventional angiogram shows the pseudoaneurysm. (d) Digital subtraction aortogram of the aortic arch, obtained after endovascular treatment with a Wallstent (Boston Scientific, Natick, Mass), shows occlusion of the lesion.
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Figure 4c. Pseudoaneurysm in a patient with a gunshot wound to the lower left side of the neck (zone I). (a) Digital subtraction angiogram shows a marginal defect in the proximal left subclavian artery (arrow). (b) Axial CT image, obtained at the level of the sternal manubrium 2 days after admission of the patient to the hospital, shows a small area of contained extravasated contrast material along the left lateral aspect of the left subclavian artery (arrow). The intimal defect seen in a has evolved into a small pseudoaneurysm. (c) Follow-up conventional angiogram shows the pseudoaneurysm. (d) Digital subtraction aortogram of the aortic arch, obtained after endovascular treatment with a Wallstent (Boston Scientific, Natick, Mass), shows occlusion of the lesion.
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Figure 4d. Pseudoaneurysm in a patient with a gunshot wound to the lower left side of the neck (zone I). (a) Digital subtraction angiogram shows a marginal defect in the proximal left subclavian artery (arrow). (b) Axial CT image, obtained at the level of the sternal manubrium 2 days after admission of the patient to the hospital, shows a small area of contained extravasated contrast material along the left lateral aspect of the left subclavian artery (arrow). The intimal defect seen in a has evolved into a small pseudoaneurysm. (c) Follow-up conventional angiogram shows the pseudoaneurysm. (d) Digital subtraction aortogram of the aortic arch, obtained after endovascular treatment with a Wallstent (Boston Scientific, Natick, Mass), shows occlusion of the lesion.
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Figure 5a. Pseudoaneurysm in a patient with a gunshot wound to zone II of the neck. (a) Axial contrast-enhanced CT image shows focal irregularity of the left vertebral artery and a change in its caliber (arrow). Note the well-defined contour and normal appearance of the right vertebral artery. (b) Selective left vertebral arteriogram shows segmental narrowing of the vessel with a pseudoaneurysm.
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Figure 5b. Pseudoaneurysm in a patient with a gunshot wound to zone II of the neck. (a) Axial contrast-enhanced CT image shows focal irregularity of the left vertebral artery and a change in its caliber (arrow). Note the well-defined contour and normal appearance of the right vertebral artery. (b) Selective left vertebral arteriogram shows segmental narrowing of the vessel with a pseudoaneurysm.
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Figure 6a. Pseudoaneurysm in a patient with a severe crushing injury to the lower neck. (a) Axial contrast-enhanced CT image obtained at the level of the thoracic inlet shows abnormal accumulation of contrast material posterior to the brachiocephalic artery (arrow). There is also a mediastinal hematoma and subcutaneous emphysema anterior to the manubrium. (b) Digital subtraction aortogram shows a small contrast material-filled lobule, which corresponds to a pseudoaneurysm, along the posteromedial aspect of the origin of the brachiocephalic artery (arrow).
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Figure 6b. Pseudoaneurysm in a patient with a severe crushing injury to the lower neck. (a) Axial contrast-enhanced CT image obtained at the level of the thoracic inlet shows abnormal accumulation of contrast material posterior to the brachiocephalic artery (arrow). There is also a mediastinal hematoma and subcutaneous emphysema anterior to the manubrium. (b) Digital subtraction aortogram shows a small contrast material-filled lobule, which corresponds to a pseudoaneurysm, along the posteromedial aspect of the origin of the brachiocephalic artery (arrow).
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Figure 7a. Pseudoaneurysm in a patient with a hematoma of the anterior neck after a transcervical gunshot wound to zone II of the neck. (a) Axial CT image shows a large area of extravasated contrast material (arrow) with a surrounding hematoma. Note the significant compression of the airway and the lateral displacement of the enhanced common carotid arteries and left jugular vein. (b) Axial CT image obtained caudad to a shows extension of the extravasated contrast material to the right of the midline. The extravasated contrast material is inseparable from the right common carotid artery (arrow). Streak artifacts in the shoulders are incidentally noted. (c, d) Aortogram (c) and selective common carotid arteriogram (d) show extravasated contrast material (ie, a pseudoaneurysm) encircling the common carotid artery.
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Figure 7b. Pseudoaneurysm in a patient with a hematoma of the anterior neck after a transcervical gunshot wound to zone II of the neck. (a) Axial CT image shows a large area of extravasated contrast material (arrow) with a surrounding hematoma. Note the significant compression of the airway and the lateral displacement of the enhanced common carotid arteries and left jugular vein. (b) Axial CT image obtained caudad to a shows extension of the extravasated contrast material to the right of the midline. The extravasated contrast material is inseparable from the right common carotid artery (arrow). Streak artifacts in the shoulders are incidentally noted. (c, d) Aortogram (c) and selective common carotid arteriogram (d) show extravasated contrast material (ie, a pseudoaneurysm) encircling the common carotid artery.
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Figure 7c. Pseudoaneurysm in a patient with a hematoma of the anterior neck after a transcervical gunshot wound to zone II of the neck. (a) Axial CT image shows a large area of extravasated contrast material (arrow) with a surrounding hematoma. Note the significant compression of the airway and the lateral displacement of the enhanced common carotid arteries and left jugular vein. (b) Axial CT image obtained caudad to a shows extension of the extravasated contrast material to the right of the midline. The extravasated contrast material is inseparable from the right common carotid artery (arrow). Streak artifacts in the shoulders are incidentally noted. (c, d) Aortogram (c) and selective common carotid arteriogram (d) show extravasated contrast material (ie, a pseudoaneurysm) encircling the common carotid artery.
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Figure 7d. Pseudoaneurysm in a patient with a hematoma of the anterior neck after a transcervical gunshot wound to zone II of the neck. (a) Axial CT image shows a large area of extravasated contrast material (arrow) with a surrounding hematoma. Note the significant compression of the airway and the lateral displacement of the enhanced common carotid arteries and left jugular vein. (b) Axial CT image obtained caudad to a shows extension of the extravasated contrast material to the right of the midline. The extravasated contrast material is inseparable from the right common carotid artery (arrow). Streak artifacts in the shoulders are incidentally noted. (c, d) Aortogram (c) and selective common carotid arteriogram (d) show extravasated contrast material (ie, a pseudoaneurysm) encircling the common carotid artery.
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Figure 8a. Pseudoaneurysm in a patient with oropharyngeal bleeding as a delayed complication of tracheal intubation. (a) Axial CT image shows prevertebral soft-tissue swelling with lateral displacement of the right common carotid artery (RCCA) and right jugular vein and displacement of the esophagus (E) to the left of the midline. (b) Axial CT image obtained just caudad to a shows a small rounded area of extravasated contrast material behind the trachea and to the right of the midline (arrow). A pseudoaneurysm was suspected. (c) Confirmatory selective conventional arteriogram shows a pseudoaneurysm of the right inferior thyroid artery (arrow). (d) Conventional angiogram obtained after endovascular treatment with coils (arrows) shows occlusion of the lesion.
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Figure 8b. Pseudoaneurysm in a patient with oropharyngeal bleeding as a delayed complication of tracheal intubation. (a) Axial CT image shows prevertebral soft-tissue swelling with lateral displacement of the right common carotid artery (RCCA) and right jugular vein and displacement of the esophagus (E) to the left of the midline. (b) Axial CT image obtained just caudad to a shows a small rounded area of extravasated contrast material behind the trachea and to the right of the midline (arrow). A pseudoaneurysm was suspected. (c) Confirmatory selective conventional arteriogram shows a pseudoaneurysm of the right inferior thyroid artery (arrow). (d) Conventional angiogram obtained after endovascular treatment with coils (arrows) shows occlusion of the lesion.
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Figure 8c. Pseudoaneurysm in a patient with oropharyngeal bleeding as a delayed complication of tracheal intubation. (a) Axial CT image shows prevertebral soft-tissue swelling with lateral displacement of the right common carotid artery (RCCA) and right jugular vein and displacement of the esophagus (E) to the left of the midline. (b) Axial CT image obtained just caudad to a shows a small rounded area of extravasated contrast material behind the trachea and to the right of the midline (arrow). A pseudoaneurysm was suspected. (c) Confirmatory selective conventional arteriogram shows a pseudoaneurysm of the right inferior thyroid artery (arrow). (d) Conventional angiogram obtained after endovascular treatment with coils (arrows) shows occlusion of the lesion.
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Figure 8d. Pseudoaneurysm in a patient with oropharyngeal bleeding as a delayed complication of tracheal intubation. (a) Axial CT image shows prevertebral soft-tissue swelling with lateral displacement of the right common carotid artery (RCCA) and right jugular vein and displacement of the esophagus (E) to the left of the midline. (b) Axial CT image obtained just caudad to a shows a small rounded area of extravasated contrast material behind the trachea and to the right of the midline (arrow). A pseudoaneurysm was suspected. (c) Confirmatory selective conventional arteriogram shows a pseudoaneurysm of the right inferior thyroid artery (arrow). (d) Conventional angiogram obtained after endovascular treatment with coils (arrows) shows occlusion of the lesion.
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Figure 9a. Pseudoaneurysm in a patient with severe crushing of the upper chest after a motor vehicle accident. The patient had fractures of the sternum and right clavicle. (a, b) Consecutive axial CT images (a obtained cephalad to b) show abnormal enhancement of a rounded structure in the upper right side of the chest just posterior to the right first rib (arrow), a finding consistent with contained extravasation of contrast material. Increased soft-tissue attenuation (ie, a hematoma) is seen surrounding the lesion. (c) Selective right internal mammary (IM) arteriogram shows active extravasation of contrast material (arrows), a finding consistent with a pseudoaneurysm. (d) Selective arteriogram obtained after endovascular treatment with coils (arrows) shows occlusion of the pseudoaneurysm.
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Figure 9b. Pseudoaneurysm in a patient with severe crushing of the upper chest after a motor vehicle accident. The patient had fractures of the sternum and right clavicle. (a, b) Consecutive axial CT images (a obtained cephalad to b) show abnormal enhancement of a rounded structure in the upper right side of the chest just posterior to the right first rib (arrow), a finding consistent with contained extravasation of contrast material. Increased soft-tissue attenuation (ie, a hematoma) is seen surrounding the lesion. (c) Selective right internal mammary (IM) arteriogram shows active extravasation of contrast material (arrows), a finding consistent with a pseudoaneurysm. (d) Selective arteriogram obtained after endovascular treatment with coils (arrows) shows occlusion of the pseudoaneurysm.
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Figure 9c. Pseudoaneurysm in a patient with severe crushing of the upper chest after a motor vehicle accident. The patient had fractures of the sternum and right clavicle. (a, b) Consecutive axial CT images (a obtained cephalad to b) show abnormal enhancement of a rounded structure in the upper right side of the chest just posterior to the right first rib (arrow), a finding consistent with contained extravasation of contrast material. Increased soft-tissue attenuation (ie, a hematoma) is seen surrounding the lesion. (c) Selective right internal mammary (IM) arteriogram shows active extravasation of contrast material (arrows), a finding consistent with a pseudoaneurysm. (d) Selective arteriogram obtained after endovascular treatment with coils (arrows) shows occlusion of the pseudoaneurysm.
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Figure 9d. Pseudoaneurysm in a patient with severe crushing of the upper chest after a motor vehicle accident. The patient had fractures of the sternum and right clavicle. (a, b) Consecutive axial CT images (a obtained cephalad to b) show abnormal enhancement of a rounded structure in the upper right side of the chest just posterior to the right first rib (arrow), a finding consistent with contained extravasation of contrast material. Increased soft-tissue attenuation (ie, a hematoma) is seen surrounding the lesion. (c) Selective right internal mammary (IM) arteriogram shows active extravasation of contrast material (arrows), a finding consistent with a pseudoaneurysm. (d) Selective arteriogram obtained after endovascular treatment with coils (arrows) shows occlusion of the pseudoaneurysm.
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Intimal Flap
Intimal flaps can be shown as a focal filling defect within the lumen that represents the partially injured vessel wall (Fig 2). The self-limited nature of some of these injuries and their benign clinical outcome has caused controversy about the diagnosis and management. Notwithstanding, small lesions may be difficult to demonstrate at CT and conceivably may go undetected.
Dissection
Dissection is not as common as occlusion in patients with penetrating injury (<2%) (4). However, as many as 33% of arterial injuries in the neck due to blunt trauma (ie, hyperextension, hyperflexion, or chiropractic therapy) are related to an underlying dissection, and mortality rates can be as high as 8% (22). CT angiography can reveal a narrowed arterial lumen with overall enlargement of the vessel diameter secondary to an intramural hematoma (Fig 10). The findings can be confirmed with MR or catheter angiography.
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Figure 10a. Dissection in a 28-year-old woman with a hyperextension injury to the neck. (a, b) Consecutive axial CT images (a obtained cephalad to b) show narrowing of the right internal carotid artery (arrow in a) with concentric soft-tissue swelling (arrow in b), which is consistent with a perivascular hematoma. (c, d) Axial fat-suppressed T1-weighted MR image (c) and cervical MR angiogram (d) show dissection of the right internal carotid artery (arrow).
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Figure 10b. Dissection in a 28-year-old woman with a hyperextension injury to the neck. (a, b) Consecutive axial CT images (a obtained cephalad to b) show narrowing of the right internal carotid artery (arrow in a) with concentric soft-tissue swelling (arrow in b), which is consistent with a perivascular hematoma. (c, d) Axial fat-suppressed T1-weighted MR image (c) and cervical MR angiogram (d) show dissection of the right internal carotid artery (arrow).
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Figure 10c. Dissection in a 28-year-old woman with a hyperextension injury to the neck. (a, b) Consecutive axial CT images (a obtained cephalad to b) show narrowing of the right internal carotid artery (arrow in a) with concentric soft-tissue swelling (arrow in b), which is consistent with a perivascular hematoma. (c, d) Axial fat-suppressed T1-weighted MR image (c) and cervical MR angiogram (d) show dissection of the right internal carotid artery (arrow).
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Figure 10d. Dissection in a 28-year-old woman with a hyperextension injury to the neck. (a, b) Consecutive axial CT images (a obtained cephalad to b) show narrowing of the right internal carotid artery (arrow in a) with concentric soft-tissue swelling (arrow in b), which is consistent with a perivascular hematoma. (c, d) Axial fat-suppressed T1-weighted MR image (c) and cervical MR angiogram (d) show dissection of the right internal carotid artery (arrow).
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Arteriovenous Fistula
Arteriovenous fistulas are caused by partial transection of an adjacent artery and vein and tend to be more clinically apparent. They are not typically seen at the time of the acute traumatic event but rather enlarge over time and manifest with specific signs (bruit). Patients with a suspected arteriovenous fistula are typically referred directly for catheter angiography. Occasionally, cross-sectional imaging with contrast-enhanced CT may provide additional information regarding the anatomy of the fistula and the relationship to adjacent structures in the axial plane.
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Pitfalls
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The ability of CT angiography to reveal arterial injuries can be limited by artifacts caused by metal, specifically bullet fragments, which may obscure vascular detail. In these cases, angiography is necessary for optimal assessment (Fig 11). Likewise, shoulder streak artifacts may limit the diagnostic information in some cases (Fig 8b). Overall, however, the reported number of inadequate studies is small (1.1%) (17).
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Figure 11a. Total occlusion in a patient with a gunshot wound to the anterior left side of the neck (zone II). (a) Axial CT image obtained at the level of C6 shows multiple metallic fragments along the trajectory of the bullet. A hematoma and soft-tissue air are present in the anterior left side of the neck. Bullet fragments are seen in the left transverse foramen (arrow) and the spinal canal. An injury of the left vertebral artery was suspected but was not clearly demonstrated. (b) Selective digital subtraction angiogram of the left vertebral artery shows total occlusion (arrow).
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Figure 11b. Total occlusion in a patient with a gunshot wound to the anterior left side of the neck (zone II). (a) Axial CT image obtained at the level of C6 shows multiple metallic fragments along the trajectory of the bullet. A hematoma and soft-tissue air are present in the anterior left side of the neck. Bullet fragments are seen in the left transverse foramen (arrow) and the spinal canal. An injury of the left vertebral artery was suspected but was not clearly demonstrated. (b) Selective digital subtraction angiogram of the left vertebral artery shows total occlusion (arrow).
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Small pseudoaneurysms may not be fully demonstrated and can be misdiagnosed with CT angiography (Fig 12). Attention to normal vascular anatomy, familiarity with vascular cross-sectional imaging, and subsequent correlation with three-dimensional reformatted images of the cervical vessels should minimize the number of examinations with false-negative results. Subtle intimal flaps and small peripheral arterial lesions of the external carotid circulation can escape recognition with CT angiography. However, these lesions are reported to have a benign clinical course and a tendency to spontaneous resolution.
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Figure 12a. Pseudoaneurysm in a 21-year-old man with a gunshot wound to the left side of the neck (zone II). (a) Axial CT image obtained at the level of the hyoid bone shows a normal bifurcation of the right common carotid artery. The origin of the right internal carotid artery (RIC) is seen posterior to the origin of the right external carotid artery (REC). A similar but more medial change in vessel contour is seen in the left common carotid artery (arrow), a finding initially interpreted as a normal bifurcation. (b) Selective left common carotid arteriogram shows a small pseudoaneurysm just proximal to the bifurcation (arrow), a finding that corresponds to the focal change in the medial vessel wall on the CT image (a). A bullet is seen posterior to the left internal carotid artery. (Reprinted, with permission, from reference 28.)
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Figure 12b. Pseudoaneurysm in a 21-year-old man with a gunshot wound to the left side of the neck (zone II). (a) Axial CT image obtained at the level of the hyoid bone shows a normal bifurcation of the right common carotid artery. The origin of the right internal carotid artery (RIC) is seen posterior to the origin of the right external carotid artery (REC). A similar but more medial change in vessel contour is seen in the left common carotid artery (arrow), a finding initially interpreted as a normal bifurcation. (b) Selective left common carotid arteriogram shows a small pseudoaneurysm just proximal to the bifurcation (arrow), a finding that corresponds to the focal change in the medial vessel wall on the CT image (a). A bullet is seen posterior to the left internal carotid artery. (Reprinted, with permission, from reference 28.)
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Conclusions
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The suspicion of vascular cervical injury requires prompt diagnostic evaluation. CT angiography has been shown to be a good noninvasive alternative to catheter angiography for the initial assessment (16,17). With the advent of multi–detector row CT and three-dimensional postprocessing workstations, images can be more accurately reproduced, similar to the familiar angiographic display (Fig 13). CT angiography can promptly reveal common vascular injuries of the neck and thoracic inlet such as vessel occlusion, pseudoaneurysm, extravasation, intimal flap, and dissection. In addition, CT has the distinct advantage of providing valuable information regarding the vertebral column and spinal canal, the status of the airway, the extent of associated hematoma, and other soft tissues of the neck. CT angiography can also aid in estimating the proximity to vascular structures by depicting the trajectory of bullets and the location of missiles or bone fragments in cases of penetrating injuries (26).
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Figure 13a. Pseudoaneurysm in a patient with a gunshot wound to the right side of the neck (zone II). (a) Axial CT image shows a large area of extravasated contrast material (arrow) adjacent to the right common carotid artery (CCA). (b) Oblique surface-rendered reformatted image (conventional angiographic view) shows the lesion. Confirmatory conventional angiography was not needed before surgical treatment.
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Abstract
LEARNING OBJECTIVES
