Acute traumatic aortic injuries, which have substantial lethal outcomes at the time of admission, are fatal in 80% to 90% of cases. These injuries are relatively rare and have nonspecific clinical presentations. Radiologists and emergency physicians need to identify the radiological signs of acute traumatic aortic injury and differentiate them from common imaging errors to ensure accurate diagnosis and determine appropriate management protocols. In combination with image-guided interventions, advances in cross-sectional imaging have enabled nonsurgical management of acute traumatic aortic injuries. Timely and precise diagnoses of these injuries following prompt treatment are essential as up to 90% of patients presenting at the hospital can undergo early repair.
Acute traumatic aortic injuries are associated with substantial lethal outcome at the time of admission fatal in 80% to 90% of cases. These injuries are relatively rare and have nonspecific clinical presentation. Early identification of the radiological signs of acute traumatic aortic injuries and differentiation from common imaging pitfalls are essential to facilitate the diagnosis of these injuries and help decide the management protocol.
Our article provides a comprehensive and updated review on the diagnosis and management of acute traumatic aortic injury, which will be useful for both emergency physicians and radiologists.
Acute traumatic aortic injuries (ATAIs), which have substantial lethal outcomes at the time of admission, are fatal in 80% to 90% of cases [
The most common location for an imaged ATAI is the aortic isthmus (approximately 90%), just distal to the origin of the left subclavian artery, because of the relative immobility of the aorta at the site of the ligamentum arteriosum [
Blunt trauma due to a high-velocity impact, such as a motor vehicle collision, is the most common mode of injury, accounting for 70% of cases, followed by a fall from height [
Cases of ATAI of the abdomen account for 11% to 15% of aortic injuries [
As a teaching institute, All India Institute of Medical Sciences obtain consent from all patients prior to all procedures and other management for using their data for educational and teaching purpose. Also, we have neither used any clinical image nor revealed any other patient information as all radiology images are anonymized.
Clinical features are often unreliable for diagnosis or exclusion of ATAI. Patients may present with nonspecific and variable clinical signs and symptoms, such as chest pain, back pain, breathing difficulty, external chest-wall injuries, and increased chest-drain output, depending on the mechanism and magnitude of the injury [
A supine chest X-ray (CXR) offers an adjunct to primary assessment and is the first line of imaging in acute trauma [
Radiographic signs in acute traumatic injury of thoracic aorta are as follows (
Loss of aortic knob or aortopulmonary window contour is the most consistent and reliable sign of ATAI of the thoracic aorta. Cases without mediastinal widening, but with loss of the sharp interface of the lung and the transverse or descending thoracic aorta, should be considered suspicious, as aortic contours should have a well-defined interface with the adjacent lung and aortopulmonary window. When applied in conjunction with mediastinal widening, this radiographic sign provides superior diagnostic accuracy.
Depressed left mainstem bronchus (more than 40 degrees from the horizontal), deviated trachea, or support devices, including endotracheal and enteric tubes toward the right (to the right of the spinous process of the third or fourth dorsal vertebra) are also indicative of ATAI and manifest due to the mass effect of mediastinal hematoma [
The left apical pleural cap is an occasionally seen in ATAI and occurs due to bleeds coursing along the left subclavian artery reflection [
A combination of these positive signs add to the diagnostic value of CXR for ATAI. In a patient with a high-energy impact, mediastinal widening with loss of aortic contours on CXR is highly indicative of ATAI and warrants further investigation with multidetector computed tomography (MDCT) and CT angiography (CTA).
Focused assessment with sonography for trauma (FAST) can detect hemothorax and pericardial effusion, which may occur in the event of a free aortic rupture. However, FAST has low sensitivity and specificity in detecting ATAI [
With the advent of modern technology, MDCT has superseded digital subtraction angiography (DSA) for the detection of ATAI [
Most ATAIs (approximately 90%) occur along the antero-medial aspect of the aortic isthmus [
Direct signs are defined on the basis of degree of injury to aortic wall with intimal, medial, and adventitial injuries displaying different radiological manifestations [
An intimal flap is seen as a linear filling defect within the aortic lumen as a result of an intimal tear (
Focal-wall outpouching or an abnormal aortic contour (pseudoaneurysm), as depicted in
Periaortic contrast extravasation is the most apparent direct sign and represents a tear of the full thickness of the aorta (
Indirect signs include periaortic hematoma (mediastinal hematoma in the thorax and retroperitoneal hematoma in the abdomen), as depicted in
Imaging errors can be technical or anatomical. Technical pitfalls include pulsation, breathing, and motion artifacts [
Several anatomical variants can cause confusion in assessments of ATAI. The most common anatomical variant is ductus diverticulum. This is an embryonic ductus arteriosus remnant. A ductus “bump” has been reported in approximately 9% of the general population [
Historically, DSA was considered the gold standard to diagnose ATAI, with a sensitivity of nearly 100%, a specificity of greater than 98%, and accuracy of more than 99%. However, with the advent of MDCT and its high ATAI sensitivity and specificity, DSA is now reserved for endovascular intervention or patients with lateralizing signs of ATAI but lacking definitive signs on CT. The signs of ATAI on DSA are vessel-wall irregularity, including breaches in continuity, contrast-material extravasation in the event of complete rupture, pseudoaneurysm, and pseudocoarctation [
Magnetic resonance imaging (MRI) has a limited role in the detection of ATAI due to long acquisition time, the need for patient immobility, and difficulty introducing certain support systems into an MRI room. However, because of the advantage of MRI characteristics in detecting aortic trauma, it can be useful in monitoring intimal injuries, follow-ups after endovascular stent placement, delayed elective surgical repair, and, in young patients, reducing radiation exposure [
Intravascular ultrasound is a helpful adjunct in scenarios in which CTA findings are equivocal because it provides cross-sectional images of the vessel wall and adjoining tissues at high resolution [
The importance of classifying injuries lies in identifying features that point to a poor prognosis, underlining the importance of correct use of MDCT signs. Various classification systems have been used in recent years to define the severity of ATAI, the most widely used of which is Society of Vascular Surgery (SVS) classification [
Direct signs of ATAI detected on MDCT can be classified according to SVS as grade 1 (intimal flap), grade 2 (intramural hematoma), grade 3 (pseudoaneurysm), and grade 4 (rupture), based on anatomical layers of the aortic wall [
The Harborview classification simplifies the SVS grading criteria of ATAI into minimal, moderate, and severe categories, on the basis of differences in treatment among these three categories (
Minimal aortic injury (MAI) includes SVS grade 1 and 2 injuries, with no external contour abnormality and an intimal tear, intraluminal or intramural thrombus, or both, <1 cm in size, with no to minimal mediastinal hematoma [
Moderate aortic injuries include larger intimal tears, larger intraluminal and intramural thrombus (>10 mm) or a pseudoaneurysm [
Treatment of all patients with ATAI begins with anti-impulse therapy (beta-blockers), antiplatelets, and anticoagulant agents [
A follow-up CT scan within 48 to 72 hours is recommended for patients with MAI to establish stability and/or resolve the abnormality. Endovascular repair can be used to treat any progression during follow-up imaging. Heneghan et al. [
Endovascular repair (
Open repair continues to be required in cases with anatomic variations that are incompatible with an endovascular approach. Such variants involve arch type, tortuosity, the diameter of proximal landing zone, and iliac vessel size [
Severe aortic injuries require immediate repair, while repair of moderate aortic injuries is undertaken after management of accompanying injuries and patient stabilization before aortic intervention, which may account for improved outcomes [
The following must be documented on MDCT for planning of endovascular stent grafting.
The length of the vascular injury and diameter of the aorta cranial and caudal to the site of injury on sagittal oblique multiplanar reformations or curved reformatted images should be documented. Overestimation of stent size by at least 15% is essential to prevent endovascular stent leakage. This is a potential problem, particularly in hypovolemic patients, as underestimates of endoprosthesis caliber may occur because of vasoconstriction in hemorrhagic shock, leading to small aortic caliber [
This needs to be measured as a left subclavian artery origin should be covered with a subsequent left carotid-subclavian artery bypass in cases with a small proximal landing zone. An angiography of the aortic arch branches therefore becomes indispensable in assessing circulation in the circle of Willis, particularly before the intentional occlusion of the left subclavian artery, without prior stenting [
Anatomic variants such as arch anatomy (type I, II, III), direct vertebral artery origin and aberrant subclavian artery (e.g., occlusion of aberrant right subclavian artery) have to be determined prior to endoprosthesis placement in the descending thoracic aorta [
Reduced diameter of access vessels may dramatically alter the appropriate approach to endovascular repair. An iliac artery diameter <7 mm has been considered a limiting factor [
Treatment and outcomes of traumatic aortic injuries in younger populations can be problematic because of the smaller aortic caliber, which can complicate graft sizing [
Minimal aortic injuries should be closely monitored by CTA after 48 to 72 hours and later on as already described. Angiography with MRI has been recommended for further follow-up.
Patients who undergo endovascular repair should also undergo graft surveillance. This is particularly important in younger patients to ensure endograft stability and integrity because the aorta remodels and lengthens with age. Aortic dilatation is more pronounced at the site of implantation and in patients receiving a stent for traumatic injury repair compared with aneurysm repair. Radiological surveillance has been recommended to be performed at 1 and 6 months, annually for the first 5 years, and then every 2 to 3 years on case-by-case basis [
ATAI is a potentially lethal entity, the outcome of which is highly dependent on early clinical suspicion, radiologic diagnosis of aortic injury, and appropriate management, including endovascular repairs. Radiologists and emergency physicians require access to direct MDCT findings based on the grading and management of aortic injuries chosen and evaluate concomitant visceral injuries that may be more life-threatening than the aortic injury itself.
No potential conflict of interest relevant to this article was reported.
Chest X-ray depicting mediastinal widening (double arrow) at the level of the aortic knob, along with obscuration of aortic contours (arrowheads) in a posttraumatic patient. Note the right paratracheal stripe widening (asterisk) and the depression of left mainstem bronchus (black arrow). The findings are highly indicative of aortic injury.
Intimal flaps in aorta. An intimal flap can be seen as a sharp, linear filling defect (arrow) in two different patients in (A) thoracic aorta and (B) abdominal infrarenal aorta.
An intraluminal thrombus in the aorta. An intraluminal thrombus can be seen as a globular, filling defect within the aortic lumen (arrow).
Intramural hematoma in the aortic wall. It presents as a crescent-shaped density in the aortic wall (arrow) in (A) axial and (B) sagittal oblique images.
A pseudoaneurysm. An abnormal aortic contour with focal bulge (arrow) just distal to subclavian artery in (A) maximum intensity projection oblique sagittal images and (B) volume rendering technique images. (C) This case was treated with endovascular stent graft placement.
Pseudoaneurysm with pseudocoarctation. A focal-contrast-filled outpouching (asterisk) leading to a significantly compressed aortic lumen (arrow) in (A) axial multidetector computed tomography images and (B) oblique sagittal maximum intensity projection images. A pseudoaneurysm/normal aortic diameter ratio >1.4 is a predictor for rupture.
Periaortic contrast extravasation. (A) Axial and (B) coronal reformatted computed tomography images in the arterial phase show an ill-defined focus of extravasated contrast matching the blood pool (arrow) in a retroaortic location with significant retroperitoneal hemorrhaging. In (C) the corresponding axial and (D) coronal reformatted portovenous phase images, the extravasated contrast (arrow) is shown expanded and spreading around the aorta.
Periaortic hematoma surrounding the aorta. Periaortic hematoma (arrowheads) can be seen closely surrounding the aorta with no intervening fat in (A) and (B). A closer look leads to a tiny focal pseudoaneurysm (arrows) as seen in (A) axial, (B) oblique sagittal, and (C) volume rendering technique images.
A pulsation artifact at the aortic root (arrow) mimicking an intimal flap. The fuzzy margins and simultaneous artifact in the main pulmonary artery (white arrowhead) helps distinguish the true injury from artifacts. Also seen in the same section is a traumatic intimal flap (blank arrow) with sharp margins in the descending aorta. An intraluminal thrombus (dashed arrow) is adjacent to it.
Ductus diverticulum versus pseudoaneurysm. A traumatic pseudoaneurysm is seen as a focal contour bulge (solid arrow) forming sharp margins with the aorta. In contrast, the ductus diverticulum (dashed arrow) has a smooth focal bulge, broad neck, and gentle obtuse angles with the aortic wall.
A pseudoaneurysm in the descending thoracic aorta and its images after stent placement. (A) An multidetector computed tomography volume rendering technique image revealing a pseudoaneurysm in descending thoracic aorta distal to the left subclavian artery with (B) a corresponding aortogram revealing the same (arrow). The patient underwent successful covered stent graft placement, as seen in (C) aortogram, which depicts normal aortic contour poststent placement. (D) A corresponding multidetector computed tomography volume rendering technique images reveal normal aortic contour poststenting.
Computed tomography signs of acute traumatic aortic injury
Direct sign | Indirect sign |
---|---|
Intimal flap | Periaortic hematoma, in close proximity with aorta and no intervening fat plane |
Intraluminal and mural thrombus | |
Focal wall outpouching | |
Abnormal aortic contour | |
Sudden change in aortic caliber (aortic “pseudocoarctation”) | |
Periaortic contrast extravasation |
Classification of acute traumatic aortic injuries (Harborview classification)
Severity | Minimal | Moderate | Severe |
---|---|---|---|
Characteristic | No external contour abnormality | External contour abnormality or intimal tear > 10 mm | Active contrast extravasation |
Intimal tear or thrombus < 10 mm | Left subclavian artery hematoma > 15 mm | ||
Management | No intervention | Semi-elective repair | Immediate repair |
Optional follow-up imaging | Stabilization of concomitant injuries | Aortic injury takes priority | |
Impulse control |