Aorta, Trauma

 

INTRODUCTION

Background: Traumatic aortic disruption is a time-sensitive injury requiring rapid and accurate diagnosis to prevent mortality. Although the clinical, or mechanism, score is of primary importance in the prompt diagnosis of patients with traumatic aortic injury (TAI), the radiologic findings play a vital supportive role.

TAI syndrome has a variable length relatively clinically silent contained rupture (pseudoaneurysm) followed by a rapid transition to free, uncontained pseudoaneurysm rupture, exsanguination, and death. The clinical challenges are to rapidly stabilize and evacuate the patient to a level I trauma center for evaluation, diagnosis, and definitive treatment before free rupture occurs.

Pathophysiology: Blunt aortic injury is part of the spectrum of blunt or deceleration polytrauma. The major regions of concern in the thorax are the heart, major vessels, abdominal organs, neck, spine, and aerodigestive tract. Penetrating injury (eg, stabbing or gunshot injury) is a different clinical entity from blunt or deceleration trauma.

Blunt or deceleration injury to the aorta is mostly confined to the thoracic aorta, except in the seat-belt injury, which involves the abdominal aorta. The radiologic evaluation must be as accurate as possible. Thoracotomy entails a significant risk, and a missed diagnosis is life threatening.

For this discussion, aortic rupture or disruption includes the aorta, the proximal portion of the great vessels, and the sinuses of Valsalva. The most common location for TAI is at the isthmus, just beyond the origins of the great vessels. In decreasing order of frequency, other locations are the descending thoracic aorta, the ascending aorta, the aortic arch, and the abdominal aorta. Ruptures at the aortic hiatus (diaphragm level) are less common. Competing theories of the mechanism of TAI have been proposed. Suffice it to say that the deceleration or crush forces interact with the asymmetric aortic fixation, causing translational and rotational forces that result in injury.

Pathologically, an aortic tear is usually transverse and involves the layers of the aorta to varying degrees. A complete tear through the intima, media, and adventitia usually leads to rapid exsanguination and death. In aortic rupture survivors, the pseudoaneurysm is contained by the adventitia and occasionally mediastinal structures.

Frequency:

  • In the US: Abdominal aortic TAI is extremely rare, with only 46 cases reported as of 1990.

    The distribution of posttraumatic aortic pseudoaneurysms differs in the classic surgical literature and the pathology (autopsy) literature. These differences are likely due to differences in survival rates with injuries in various locations. Locations of TAI, as adapted from the report by Parmley et al in 1958, are as follows: ascending aorta, 17 (9.9%) of 171 cases; arch, 16 (9.4%); isthmus, 95 (55.6%); thoracic aorta, 27 (15.8%); abdominal aorta, 11 (6.4%); and multiple locations, 5 (2.9%). Locations of TAI, as adapted from Kadir's report in 1986, are as follows: ascending aorta, 1%; innominate artery, 4.5%; left common carotid artery, 0.8%; left subclavian artery, 2.7%; aortic isthmus, 88.2%; descending aorta, 1.8%; and aortic hiatus (diaphragm level), 0.4%.

    Investigators from the Medical College of Wisconsin (unpublished data, 1990) performed a retrospective review of 181 consecutive patients with blunt aortic trauma (BAT) in January 1986 through August 1990. The patients underwent angiography, for which the yield for TAI was 17%; this finding corresponded to the historic rate of 10-20%. Locations of TAI were as follows: isthmus, 23 (74%) of 31 (circumferential artery, 16 [52%] and anteromedial artery, 7 [23%]); innominate artery, 4 (13%); subclavian artery, 1 (3%); undersurface of the arch, 1 (3%); and other, 10 (32%).

    Traditional clinical series report TAI to occur at the aortic isthmus in 95% of patients surviving long enough to undergo surgery versus 45-66% found in autopsy studies. The speed and efficiency of the trauma response system affects the overall survival rate and distribution of the rupture.

Mortality/Morbidity: Traumatic aortic rupture is an extremely unstable condition. The patient's survival depends on rapid diagnosis and treatment. Regional trauma centers and rapid patient transport have dramatically improved survival rates.

  • In 1958, Parmley et al reported that 85% of patients with aortic injury died prior to reaching hospital and that their survival was dependent on the time from injury to surgery. Although some traumatic aortic pseudoaneurysms stabilize, mortality from untreated injuries continues. Of the subset of patients surviving at least 1 hour, death rates from TAI varied with the time until surgery, as follows (Parmley, 1958): 15% with an interval of 6 hours; 27%, 24 hours; 61%, 1 week; and 88%, 4 months.
  • In 1976, Kirsh et al reported a survival rate of approximately 70% with prompt and aggressive treatment.
  • In 1997, Fabian et al reported a 31% mortality rate in 274 patients (207 were operated on) who presented to the hospital with TAI. Approximately two thirds of deaths were due to the aortic rupture, and the rest were due to associated injuries.

Race: No race-related difference in anatomy or physiology causes a predisposition to TAI. Differences in the incidence of TAI are strictly due to the likelihood of severe blunt injury.

Sex: No sex-related difference in anatomy or physiology causes a predisposition to TAI. Differences in the incidence of TAI are strictly due to the likelihood of severe blunt injury.

Age: TAI is essentially an entity of the adult. Pediatric cases are extremely rare.

Anatomy: The most common diagnostic challenge is differentiating a traumatic aortic isthmus pseudoaneurysm from a normal ductus diverticulum (type III ductus). Ductus diverticulum is commonly thought of as the remnant of the ductus arteriosum, although Grollman theorized that the ductus is a remnant of the right dorsal aortic root. The aortic isthmus is located anteromedially, just distal to the origin of the left subclavian artery. This location is most commonly ruptured. It is also the location of the ductus diverticulum; therefore, diagnostic confusion can result. Smooth anteromedial outpouching of the aortic isthmus represents the normal ductus diverticulum and should not be confused with a pseudoaneurysm.

The Goodman classification (from 1982) describes the contour of the isthmus as follows: Type I involves a concave isthmus contour; type II, mild straightening or convexity without a discreet bulge; and type III, a discrete focal bulge of the aortic isthmus called the ductus diverticulum.

Another normal variant is a fusiform enlargement or prominence of the proximal descending aorta. It is considered normal unless other findings of TAI are present.

Clinical Details: BAT is usually the result of a crush or deceleration injury, which often occurs during a motor vehicle accident or a fall from substantial height. Clinical evaluation and triage are vital to the patient's survival. The severity, likelihood, and clinical impact of potential injuries must be considered in the context of the patient's polytrauma as a whole.

The clinical signs and symptoms associated with TAI are nonspecific and for the most part indirect. The exception is the rapid onset of severe hypovolemic shock associated with a free (noncontained) aortic rupture. The signs and symptoms of contained TAI are more related to the associated injuries of polytrauma, such as fractures, spinal cord, and head injury. Some centers use criteria such as mechanism or visible steering wheel injury in their polytrauma protocols. Fortunately, the evaluation for TAI is fairly easily incorporated into trauma center workflow.

The integrity of the airway, cardiovascular system, and spinal cord must be addressed before a potential blunt aortic injury is considered. Splenic or aortic disruption must be considered in patients with blunt trauma who present in hypovolemic shock. The choice and timing of plain radiography, CT, and/or angiography must be considered in context of the patient's condition as a whole.

Preferred Examination: CT and angiography are the prime imaging modalities in planning treatment for blunt trauma.

As yet, no ideal diagnostic algorithm is available for TAI. The clinical history (mechanism score) is often used for the prompt diagnosis of TAI. Plain radiographic evaluation is usually the first to be performed. The optimal upright posteroanterior (PA) chest evaluation is often deferred for a portable examination with the patient still on the backboard.

Either CT or angiography may be performed, depending on institutional preferences, the patient's condition, and the likelihood of other injuries. For example, a patient with hemorrhage from a crushed pelvis would undergo angiography first, whereas a hemodynamically stable patient with a suspected renal or splenic injury would undergo CT first. Diagnostic imaging should be deferred in patients presenting in hypovolemic shock or cardiac arrest.

Except for cases involving exsanguinating hemorrhage from a pelvic fracture, angiography has no role in the early treatment of a patient with polytrauma who is in unstable condition. MRI generally has no role in the acute evaluation of polytrauma. Some centers advocate the early use of transesophageal echography, which is beyond the scope of this discussion.

 

DIFFERENTIALS

Abdominal Aortic Aneurysm, Diagnosis
Abdominal Aortic Aneurysm, Rupture
Aorta, Coarctation
Aorta, Dissection
Aortic Regurgitation
Aortic Stenosis


Other Problems to be Considered:

Atherosclerosis

Bronchial and/or intercostal artery

Ductus diverticulum

Normal fusiform dilation of isthmus

Polytrauma - Spinal cord injury; bleeding; behavioral change; renal failure; and tracheobronchial tree, heart, and/or pericardial injuries

 

X-RAY

Findings: After a clinical evaluation, most patients are best evaluated with a chest radiography (CXR) followed by CT, angiography, or immediate surgery, depending on the specific results of the case and institutional preferences. In the typical emergency-department evaluation of a patient with blunt trauma, an initial screening radiograph of the chest and cervical spine are obtained. The patient's clinical condition, the severity and mechanism of the trauma, and the initial radiographic findings are used to determine if angiography or CT is indicated.

BAT has several classic radiographic signs. These signs are more a result of multiple injuries or the radiographic technique used and less a specific sign of BAT. Regarding the popular mediastinal widening sign, some trauma radiologists believe that the mediastinal contour is a better sign of BAT than the actual transverse diameter.

Stark et al reviewed the CXR findings in 49 cases of aortic rupture (Stark, 1987). A widened mediastinum, partial blurring of the aortic shadow, a left apical cap, and right tracheal deviation were the most common findings. No patient in the study had normal CXR results. Unfortunately, these findings are often nonspecific, and they can be present in patients without significant aortic injury. Therefore, clinical evaluation is essential in determining which patients require further studies.

The frequency of radiographic signs of TAI, as adapted from the report by Stark et al, are as follows: wide mediastinum, 70%; partial obliteration of the descending aorta, 67%; a left apical cap, 65%; downward displacement of the left bronchus, 65%; tracheal deviation to the right, 63%; obscuration of the aortic arch, 55%; a right paratracheal stripe thickening, 53%; deviation of the nasogastric (NG) tube to the right, 50%; enlarged abnormal aortic contour, 39%; left hemothorax, 35%; a displaced left paraspinal stripe, 35%; a displaced right paraspinal stripe, 33%; and a fracture of the first rib, 16%.

Radiographic signs of TAI, as adapted from the report by Kirsh et al, are as follows (Kirsh, 1976): widened mediastinum, 42; abnormal aortic contour, 41; deviation of the trachea to the right, 14; depression of the left mainstem bronchus, 13; left pleural effusion, 15; and negative signs, 1.

The Table below shows the poor predictive value of the classic CXR signs of TAI.

Frequency of Abnormal Radiographic Signs in Patients With Suspected TAI

Sign Aortic Laceration, % Normal Aortographic Findings, %
Mediastinum >8 cm 75.5 73.3
Indistinct descending aortic arch contour 75.5 94.7
Indistinct descending aortic contour 12.2 15.4
Trachea displaced to the right 61.2 31.6
NG tube or esophagus displaced to the right 66.7 23.1
Left mainstem bronchus displaced inferiorly 53.1 26.3
Pleural apical cap 36.7 42.1
Fractures of rib 1 or 2 17.0 30.0

Source.—Adapted from Kadir, 1986.

Degree of Confidence: Diagnoses such as masses, infection, and chronic injury may simulate acute TAI.

False Positives/Negatives: In 1998, Demetriades et al reported a similar, significant false-negative rate with initial CXR findings in patients with TAI. They recommend follow-up CT in all patients with suspected TAI.

  

CAT SCAN

Findings: The days of conventional angiography as the criterion standard for the evaluation of BAT are likely numbered. The historic tradeoff between CT and angiography was image resolution versus cross-sectional imaging. The submillimeter resolution available with angiography (cut-film and then digital subtraction angiography [DSA]) was invaluable for delineating the sometimes-subtle findings of traumatic aortic disruption. CT scanning times were long, and sections were thick. With CT, the intravascular density of contrast material was far less than that currently achievable. False-negative results could occur with subtle injuries. False-positive CT findings were possible with mediastinal hemorrhage from venous bleeding and irregularities of the vessel wall due to atherosclerosis.

Recent developments in technology have allowed CT to catch up to angiography in terms of image quality. The current generation of multidetector-row spiral CT scanners can acquire 32 sections per second with submillimeter section thicknesses and a 512 X 512 image matrix. CT is ideal for evaluating the nonarterial injuries in patients with polytrauma such as those with brain, spine, pelvis, spleen, liver, and/or kidney injuries. A single intravenous administration of contrast material can be used for a combined vascular and nonvascular evaluation.

Technologic improvements are a double-edged sword. With decreasing section thickness comes a commensurate increase in the number of images to be interpreted. Examinations involving 600-800 individual sections are possible. High-speed diagnostic workstations can help in managing the data load. With these workstations, reviewers can rapidly scroll through high-resolution datasets and combine the data into fewer, thicker sections.

Another data-management tool returns us full circle to the angiographic interpretation of BAT images. Cross-sectional imaging may be processed with 3-dimensional (3D) and 2-dimensional (2D) surface reconstruction techniques. These reconstruction techniques produce images that simulate anatomic dissections and angiograms. These images allow the clinician to obtain an examination overview and to focus on particular areas of pathology or surgical interest. As technology improves, reconstructed images will eventually supplant source images in routine image interpretation.

The imaging endpoints of reconstructed CT and conventional angiograms are essentially similar. Similar interpretation approaches are likely to apply. Angiographic signs and interpretation skills should have significant overlap with the evaluation of CT angiograms.

Authorities generally agree (with a vocal dissenting minority) that CT is an excellent screening modality for patients not undergoing aortography. CT is particularly convenient in patients with polytrauma who are undergoing other CT studies at the same time. Angiography had imaging advantages over previous generations of CT, because of the scanner design. However, new multidetector-row units may allow CT to eventually become the new criterion standard.

For a single detector-row spiral CT acquisition, the following parameters may be used: 3 mL/s X 100-150 mL, 30-s delay, 3-mm collimation, pitch of 1.5, imaging from the diaphragm to the apex, and 1 X 1 reconstruction if 3D imaging is desired. If CT angiographic reconstruction is used, the axial source images should be reviewed.

The advantages of CT are that it is quick; noninvasive; useful in evaluating multiple traumas at the same time; and capable of providing a larger field of interest, particularly with fast spiral technology.

The disadvantages are the following: (1) CT may be limited by partial-volume effects (eg, those due to small disruption or subtle intimal injury). (2) Cardiac and respiratory motion (eg, artifact in the region of the aortic root) can affect the image quality. (3) CT can expose the patient to contrast material, particularly if angiography and/or embolization are required.

Degree of Confidence: TAI may be diagnosed on the CT scans as a direct or indirect sign. Direct signs (eg, aortic intimal flap, contour abnormality) are more accurate than indirect signs (eg, mediastinal, periaortic hematoma).

Studies have shown that CT is sensitive for TAI (83-100%) with high negative predictive value (NPV) of 99-100%. Its specificity of 54-99.8%, and its related positive predictive value (PPV) of 9-89% are generally lower than those of angiography.

In 1996, Mirvis et al explained the reason for the lower specificity of CT. They stratified the sensitivity and specificity results based on direct and indirect signs. Although direct signs were 99% specific, they reported that the specificity of indirect signs was only 87%.

Most of the studies that show a 100% NPV for CT are limited to clinical follow-up. Data about follow-up CT or angiography in patients with negative initial CT findings are limited. Further study is needed before the field of CT in traumatology is considered mature.

A number of investigators recommend that CT is the screening examination of choice for TAI as well as for other injuries (eg, pulmonary laceration, pneumothorax, tracheobronchial, spinal injury). Unless the CT results are diagnostic, confirmatory angiography is generally required. Angiography or preemptive surgery is advised if TAI is highly suspected, either on the basis of the clinical or plain radiographic findings. In 1999, Pate et al reported that CT led to a 50% reduction in the use of angiography; this is a benefit in regions with limited access to angiography.

False Positives/Negatives: Atelectasis, the thymus, or the pericardial recess can mimic mediastinal hematoma.

Partial-volume and cardiorespiratory motion effects can lead to false-positive or false-negative findings, particularly in the region of the aortic root. Ductus diverticulum or other variants may be confused with TAI. Mediastinal hematoma may be due to venous or arterial injury. Subtle ruptures, particularly intimal injuries, may not be clearly delineated. Nevertheless, authors of published reports speak highly of CT evaluation.

Recent studies are showing improved results with CT. Various grading schemes have been described, and these are likely to address the false-positive issue.

 

ULTRASOUND

Findings: Transesophageal echography (TEE) for TAI diagnosis has its proponents, which support it mostly because of its portability and rapid availability in a trauma center setting. TEE has significant proponents in the pediatric trauma literature.

Degree of Confidence: Limitations of the modality include blind spots where the aorta is suboptimally imaged with ultrasonography. Like angiography, TEE is operator and reader dependent and must be performed by well-trained personnel.

 

ANGIOGRAPHY

Findings: Aortography may be performed with a standard 100-cm-long 5F pigtail catheter, although a 110-cm-long 6F pigtail (Merit) is preferred. The longer length is helpful to reach the aortic root in tall patients. With the 6F catheter, the 27-mL/s contrast-agent injection rate typical of 100-cm-long 5F catheters can be exceeded. The 6F pigtail may be more rigid than 5F catheters. Predilation of the tract with a 5F or 6F dilator or a 6F sheath is recommended.

Although most TAI occur in the region of the isthmus, the entire thoracic aorta should be evaluated. To exclude aortic regurgitation and other aortic root injury, the catheter is first placed above the sinuses of Valsalva. A test injection is used to verify that the catheter tip does not interfere with the aortic root to avoid spurious aortic regurgitation. The contrast-agent injection rate is 20- to 30-mL/s for 50 mL, depending on the patient's cardiac output. Patients with BAT are typically young and present in a state of high cardiac output.

The injection and imaging rate may be adjusted on the basis of the test injection results. For intubated patients, mechanical ventilation may be suspended during each angiographic run. Once the aortic root and the ascending aorta are cleared, the catheter may then be withdrawn to the upper ascending aorta to concentrate on the Isthmus and distal aorta. The side holes of the catheter should be positioned just proximal to the area of interest for maximum opacification.

Aortographic signs of aortic rupture may be subtle. A high index of suspicion is important. A minimum of 2 angiographic projections is required to exclude TAI. Typical projections are a 45° left anterior oblique (LAO) view followed by a steep LAO or lateral view. When an isthmus abnormality is suspected, obtain a lateral or steep LAO view to differentiate between the contour abnormality of a pseudoaneurysm and a normal ductus. Other projections are obtained depending on clinical suspicion and the preliminary angiographic findings. In one case from the author's experience, a rupture was better seen on the PA image than on the shallow oblique image (no steep oblique or lateral image had been obtained).

Biplane imaging or rotational angiography can reduce the examination time and the contrast agent load. A biplane combination of 45° right anterior oblique (RAO) and/or LAO views may be used. The imaging frame rate, the source-to–image intensifier distance (SID), and the projection may be altered to accommodate tube-loading, kilovolt-peak issues, or cardiac output. A typical frame rate is 4-6 per second. DSA magnification may be helpful in equivocal cases. Tube loading limits may become significant for steep oblique or lateral magnified studies. Rotational angiography typically increases tube loading. Whenever tube loading becomes an issue, the traditional steps may be taken, that is, a reduction in the frame rate and the duration of the examination, in the SID, in the magnification, or the dose (increased DSA quantum mottle).

Degree of Confidence: Angiography is the traditional modality for evaluating patients with suspected acute TAI. Approximately 10-20% of patients with blunt trauma who are referred for angiography have positive angiographic findings. In BAT, angiography is best used as a confirmatory tool for patients with positive CT findings or as a primary diagnostic tool in hemodynamically stable patients in whom the clinical suspicion for TAI is high.

In 1995, Gavant reported that angiography is 94% sensitive and 96% specific. In 1998, Fabian et al reported that angiography had a sensitivity of 100%, a specificity of 97%, an NPV of 97%, and a PPV of 97%.

False Positives/Negatives: A high index of suspicion is required when a patient is evaluated for TAI. The mortality rate for a missed diagnosis (false-negative angiographic finding) is high. Equivocal cases should undergo close clinical and imaging follow-up or exploratory surgery. Surgery is a relatively benign procedure when the risk of morbidity and mortality associated with a missed TAI is considered. As the quality of CT and other noninvasive imaging modalities improve, the surgical exploration rate can be expected to decrease.

False diagnoses can be minimized by paying meticulous attention to the imaging technique and by following-up any equivocal findings. False-negative angiographic results may occur when the injury is subtle, when it is not seen in profile (out of plane), or when the injured area is not delineated by the contrast agent column or when it is out of the field of view.

False-positive angiographic results may occur as a result of inadequate angiographic technique (catheter position, injection rate, exposure and position), motion or inflow artifacts, comorbidities (eg, atherosclerosis), the presence of nontraumatic entities (eg, infection), and normal variants in the anatomy. Common variants at the isthmus are a smooth fusiform circumferential widening at the isthmus, a ductus diverticulum, and an asymmetric ductus with bronchointercostal artery. No other signs of TAI should be present if a normal variant is to be safely diagnosed.

 

INTERVENTION

Intervention: The greatest and most important role for the radiologist is in integrating and coordinating with the rest of the trauma team to triage and facilitate the appropriate and prompt care for this all too common and life-threatening entity. Radiologic intervention has a limited role in the current management of BAT.

Transcatheter embolization of minor arterial injuries or other associated injuries may be appropriate for some patients who present with BAT. The early data on stent-graft treatment of TAI is positive. Compared with stent-graft treatment of abdominal aortic aneurysm disease, this treatment has differences in time requirements, anatomy, and technique. The procedure should be attempted only in centers familiar with the stent-graft procedure. For now, the standard of care is urgent surgical intervention with thoracotomy and repair.

Medical/Legal Pitfalls:

  • No specific legal issues are related to this topic.
  • The equipment, the personnel and their training, and the level of service must be adequate, as in all of radiology.

 

PICTURES
Caption: Picture 1. Aorta, trauma. CT scan shows aortic disruption at the aortic isthmus. Increased attenuation is present in the mediastinum; this indicates hematoma and a left pleural effusion. The linear lucency across the aortic lumen may be an artifact. The pseudoaneurysm is not seen on this image.
Picture Type: CT
Caption: Picture 2. Aorta, trauma. Left anterior oblique (45°) angiogram shows aortic disruption at the aortic isthmus. An irregular outpouching is present with an intimal flap and an angular transition that represents a contained disruption at the isthmus. This appearance is in contrast to the otherwise normal-appearing vessels.
Picture Type: Image
Caption: Picture 3. Aorta, trauma. Left anterior oblique (45°) angiogram shows disruption of the innominate artery. A fairly well-contained pseudoaneurysm originates near the innominate artery.
Picture Type: Image
Caption: Picture 4. Aorta, trauma. Chest radiograph shows widening of the mediastinal contour and deformity and blurred margins of the superior mediastinum.
Picture Type: X-RAY
Caption: Picture 5. Aorta, trauma. Posteroanterior angiogram shows disruption of the innominate artery. This early image shows a poorly circumscribed pseudoaneurysm or extravasation.
Picture Type: Image
Caption: Picture 6. Aorta, trauma. Posteroanterior angiogram shows disruption of the innominate artery. This delayed image shows continuing expansion of the extravasation of contrast material. The outer margins of the pseudoaneurysm are better delineated on this image than on others.
Picture Type: Image
Caption: Picture 7. Aorta, trauma. Left anterior oblique (45°) angiogram shows disruption of the innominate artery. A well-circumscribed narrow-neck pseudoaneurysm is noted along the superior margin of the aortic isthmus. The findings suggest a daughter injury immediately distal to the main outpouching.
Picture Type: Image
Caption: Picture 8. Aorta, trauma. Posteroanterior angiogram shows multiple great-vessel injuries. The image shows a cut-off of the left vertebral artery and a pseudoaneurysm of the left subclavian artery. The right common carotid artery is also occluded. The occlusions are probably due to intimal flap ballooning into the vessel lumen that occludes it.
Picture Type: Image
Caption: Picture 9. Aorta, trauma. Left anterior oblique angiogram (LAO) shows the typical appearance of the normal ductus diverticulum. The smooth walls and transition would be better delineated on a steep LAO or lateral view (not shown).
Picture Type: Image
Caption: Picture 10. Aorta, trauma. Chest radiograph shows a chronic isthmus pseudoaneurysm, which is demonstrated as a smooth outpouching near the aortic knob. The calcified rim indicates that this injury is several years old.
Picture Type: X-RAY
Caption: Picture 11. Aorta, trauma. Image shows a chronic isthmus pseudoaneurysm, which is indistinguishable from the acute variety. The calcium seen on plain radiographs is not readily seen on digital subtraction angiograms (DSAs).
Picture Type: Image
Caption: Picture 12. Aorta, trauma. Chest radiograph shows a focal isthmus pseudoaneurysm. The superior mediastinum is distorted, with a loss of the normal aortic knob contour. The right mediastinal edge is blurred as well. Although not measured, the mediastinum is also wide.
Picture Type: X-RAY
Caption: Picture 13. Aorta, trauma. CT scan shows a focal isthmus pseudoaneurysm. The image shows increased attenuation of the mediastinum, which is consistent with mediastinal hematoma. The descending aortic contour is bilobed consistent with pseudoaneurysm formation.
Picture Type: CT
Caption: Picture 14. Aorta, trauma. Posteroanterior angiogram shows a focal isthmus pseudoaneurysm. A fairly sharply demarcated, rounded, doubly dense region is seen superimposed on the isthmus area. Its differentiation from a normal ductus may be difficult.
Picture Type: Image
Caption: Picture 15. Aorta, trauma. Left anterior oblique (45°) angiogram shows a focal isthmus pseudoaneurysm. Image shows delayed washout from the slightly irregular isthmus bulge that supports the diagnosis of pseudoaneurysm. The remainder of the aorta is smooth in this 19-year-old male patient.
Picture Type: Image
Caption: Picture 16. Aorta, trauma. Chest radiograph shows spontaneous rupture of the isthmus, a mycotic aneurysm secondary to Salmonella pneumonitis infection. The widening and distortion of the superior mediastinum is indistinguishable from a traumatic pseudoaneurysm. This patient had no history of significant trauma and presented with chest pain. At surgery, a necrotic node was found, and Salmonella organisms were cultured. A faint bronchogram was noted retrospectively.
Picture Type: X-RAY
Caption: Picture 17. Aorta, trauma. CT scan shows spontaneous rupture of the isthmus, a mycotic aneurysm secondary to Salmonella pneumonitis infection. Increased attenuation in the mediastinum is indistinguishable from a hematoma. The calcified outpouching of the aorta suggests a more chronic condition.
Picture Type: CT
Caption: Picture 18. Aorta, trauma. Left anterior oblique (40°) angiogram shows spontaneous rupture of the isthmus, a mycotic aneurysm secondary to Salmonella pneumonitis infection. An isthmus outpouching has reduced contrast enhancement and a slightly irregular contour and margins in comparison to the surrounding aorta. This appearance is indistinguishable from that of a traumatic pseudoaneurysm.
Picture Type: Image
Caption: Picture 19. Aorta, trauma. Angiogram shows a spurious aortic regurgitation. The pigtail catheter is placed too close to the aortic valves (sinuses of Valsalva) and interferes with normal valvular function and regurgitation. Repeat angiogram obtained after the catheter was repositioned showed normal findings. The position of the catheter should be verified with a vigorous test injection.
Picture Type: Image
Caption: Picture 20. Aorta, trauma. Left anterior oblique (LAO) (30°) angiogram shows a tear on the undersurface of the aortic arch. This case is unusual in that the oblique view fails to demonstrate all of the patient's injuries. This moderate LAO view demonstrates only the atherosclerotic and hypertensive changes.
Picture Type: Image
Caption: Picture 21. Aorta, trauma. Left anterior oblique (4°) angiogram shows a tear on the undersurface of the aortic arch. This nearly posteroanterior (PA) view demonstrates a small but definite irregular and hypodense pseudoaneurysm extending from the undersurface of the aortic arch. This case illustrates the need for multiple angiographic projections before the findings can be declared normal.
Picture Type: Image
Caption: Picture 22. Aorta, trauma. Angiogram shows a focal isthmus traumatic pseudoaneurysm. This example demonstrates an anteromedial bulge, intimal flap, acute-angle transition, irregular contour, and contrast-material hang up in this 45-year-old female patient.
Picture Type: CT
Caption: Picture 23. Aorta, trauma. Posteroanterior (PA) angiogram shows a subtle intimal flap. Only a hint of the intimal flap at the anteromedial isthmus is depicted in this 31-year-old man. The angiographic findings are otherwise normal.
Picture Type: Image
Caption: Picture 24. Aorta, trauma. Left anterior oblique (30°) angiogram shows a subtle intimal flap. Image demonstrates a focal anteromedial isthmus bulge with the intimal flap shown to better advantage.
Picture Type: Image
Caption: Picture 25. Aorta, trauma. Posteroanterior angiogram shows a subtle isthmus tear in a 21-year-old man. On this view, the anteromedial isthmus abnormality is the only subtly demonstrated as a round, superimposed density in this otherwise unremarkable study.
Picture Type: Image
Caption: Picture 26. Aorta, trauma. Left anterior oblique (45°) angiogram shows a subtle isthmus tear. This digital subtraction angiogram clearly demonstrates the focal bulge of a pseudoaneurysm, with a linear defect of the intimal flap shown superiorly.
Picture Type: Image
Caption: Picture 27. Aorta, trauma. Posteroanterior (PA) angiogram shows a subtle circumferential isthmus tear in a 72-year-old man. Image demonstrates the mildly irregular lateral surface of the aortic isthmus. This abnormality could easily be confused with atherosclerosis.
Picture Type: Image
Caption: Picture 28. Aorta, trauma. Left anterior oblique (45°) digital subtraction angiogram shows a subtle circumferential isthmus tear. The findings confirm the irregularity, and the image shows a focal bulge with a sharply angled superior transition.
Picture Type: Image
Caption: Picture 29. Aorta, trauma. Posteroanterior (PA) angiogram shows an anteromedial isthmus rupture in a 19-year-old man. Image shows an anteromedial bulge with a slightly irregular contour and a suggestion of an acute-angle transition with the aortic wall. This appearance might be confused with that of a ductus diverticulum.
Picture Type: Image
Caption: Picture 30. Aorta, trauma. Left anterior oblique (45°) digital subtraction angiogram shows an anteromedial isthmus rupture. Image clearly demonstrates the linear defect of an intimal flap, which confirms the diagnosis of an aortic rupture.
Picture Type: Image
Caption: Picture 31. Aorta, trauma. Left anterior oblique (45°) angiogram shows a circumferential isthmus rupture. Irregularity and acute angulation are noted in this acute traumatic aortic injury (TAI).
Picture Type: Image
Caption: Picture 32. Aorta, trauma. Chest radiograph shows a circumferential isthmus rupture. The aortic knob is not depicted, and the mediastinum is wide and deformed.
Picture Type: X-RAY
Caption: Picture 33. Aorta, trauma. Left anterior oblique (45°) angiogram shows a circumferential isthmus rupture. The contour of the proximal margin of the pseudoaneurysm is shown in relief against the adjacent aorta.
Picture Type: Image
Caption: Picture 34. Aorta, trauma. Angiogram shows a circumferential isthmus rupture. The surface irregularity, contour abnormality, and acute angulation of the transition make this diagnosis easy.
Picture Type: Image
Caption: Picture 35. Aorta, trauma. Chest radiograph shows an isthmus tear and atherosclerosis in a 79-year-old man. Image shows blurring of the aortic knob with a double shadow. The extensive subcutaneous emphysema probably related to another injury.
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Caption: Picture 36. Aorta, trauma. Left anterior oblique angiogram shows an isthmus tear and atherosclerosis. Although the appearance of the surrounding and underlying atherosclerosis confuses the diagnosis, a definite focal bulge at the anteromedial isthmus is noted. This was proven to be a traumatic aortic injury (TAI).
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Caption: Picture 37. Aorta, trauma. Left anterior oblique (30°) angiogram shows atherosclerosis without an aortic injury. No focal variation in the atherosclerotic pattern is present to suggest injury.
Picture Type: Image
Caption: Picture 38. Aorta, trauma. Left anterior oblique (60°) angiogram shows atherosclerosis without an aortic injury. No focal variation in the atherosclerotic pattern is present to suggest injury.
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Caption: Picture 39. Aorta, trauma. Left anterior oblique angiogram shows a normal fusiform aortic isthmus. Angiogram shows smooth, fusiform widening of the isthmus with a smooth transition at an obtuse angle with the descending aorta. No persistence of contrast opacification is shown. This 31-year-old patient was referred for surgery, and a normal aorta was found. The angiographic findings were false-positive. In the author's experience, subsequent patients with similar findings have not been referred for thoracotomy, and they have not developed signs or symptoms of aortic rupture.
Picture Type: Image
Caption: Picture 40. Aorta, trauma. Left anterior oblique (45°) angiogram shows a normal aorta with a fusiform isthmus and atherosclerosis. No abnormality is superimposed over the normal variant fusiform appearance of the isthmus and the typical appearance of atherosclerosis.
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Caption: Picture 41. Aorta, trauma. Angiogram shows a chronic circumferential isthmus rupture. The appearance should not be confused with that of the normal fusiform dilation in the Image 40. Note the acute angles of the transition and the irregular margins. This patient was 9 years old and was involved in a motor vehicle accident.
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Caption: Picture 42. Aorta, trauma. Left anterior oblique (20°) angiogram shows a normal bronchointercostal artery. The image shows an acute widening in the anteromedial isthmus region, with linear enhancement projecting superomedially. This 40-year-old man underwent surgical exploration, with negative results. The finding was retrospectively identified as a bronchial artery aorta.
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Caption: Picture 43. Aorta, trauma. Left anterior oblique (45°) angiogram shows a normal bronchointercostal artery with a ductus diverticulum. The initial image in this young female patient who was injured in a motor vehicle accident shows a possible contour abnormality in the region of the isthmus.
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Caption: Picture 44. Aorta, trauma. Left anterior oblique (70°) angiogram shows a normal bronchointercostal artery with a ductus diverticulum. The anteromedial isthmus outpouching is asymmetric, with a questionable distal irregularity. The differential diagnosis includes ductus diverticulum and traumatic aortic injury (TAI).
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Caption: Picture 45. Aorta, trauma. Lateral digital subtraction angiogram shows a normal bronchointercostal artery with a ductus diverticulum. The anteromedial isthmus outpouching is asymmetric, and a right-angle transition is depicted proximally. The margins are smooth, and no hang up is shown. Because of the severity of the patient's other injuries, surgical exploration was recommended. During surgery, a normal isthmus region was found.
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Caption: Picture 46. Aorta, trauma. Anteroposterior digital subtraction angiogram shows a subtle isthmus pseudoaneurysm. The image demonstrates no abnormality.
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Caption: Picture 47. Aorta, trauma. Left anterior oblique (45°) digital subtraction angiogram shows a subtle isthmus pseudoaneurysm. The image shows a slightly asymmetric anteromedial bulge that might represent a small ductus diverticulum.
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Caption: Picture 48. Aorta, trauma. Lateral digital subtraction angiogram shows a subtle isthmus pseudoaneurysm. This image better demonstrates the irregular contour and the right-angle transition of the pseudoaneurysm.
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Caption: Picture 49. Aorta, trauma. Lateral screen-film angiogram shows a subtle isthmus pseudoaneurysm. Conventional subtraction image confirms demonstrates the irregular contour of the isthmus rupture. The image also suggests a linear defect of the intimal flap. Surgical exploration confirmed subtle aortic injury. CT scan of the aortic arch (not shown) showed no abnormality in the region of the traumatic pseudoaneurysm that was demonstrated on the angiogram.
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Caption: Picture 50. Aorta, trauma. Left anterior oblique (45°) angiogram shows a replaced origin of the left vertebral artery. Familiarity with normal variants such as this aortic origin of left vertebral artery is essential.
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