This is the current release of the guideline.

This guideline updates a previous version: Holtzman SR, Yucel EK, Rybicki FJ, Baum RA, Desjardins B, Flamm SD, Foley WD, Koss SA, Mammen L, Mansour MA, Narra VR, Expert Panel on Vascular Imaging. ACR Appropriateness Criteria® blunt chest trauma -- suspected aortic injury. [online publication]. Reston (VA): American College of Radiology (ACR); 2009. 5 p. [37 references]

The appropriateness criteria are reviewed biennially and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

Blunt chest trauma, suspected aortic injury

To evaluate the appropriateness of initial radiologic examinations for blunt chest trauma–suspected aortic injury

Patients with blunt chest trauma, suspected aortic injury

Utility of radiologic examinations in differential diagnosis

Literature Search Procedure

The Medline literature search is based on keywords provided by the topic author. The two general classes of keywords are those related to the condition (e.g., ankle pain, fever) and those that describe the diagnostic or therapeutic intervention of interest (e.g., mammography, MRI).

The search terms and parameters are manipulated to produce the most relevant, current evidence to address the American College of Radiology Appropriateness Criteria (ACR AC) topic being reviewed or developed. Combining the clinical conditions and diagnostic modalities or therapeutic procedures narrows the search to be relevant to the topic. Exploding the term "diagnostic imaging" captures relevant results for diagnostic topics.

The following criteria/limits are used in the searches.

1. Articles that have abstracts available and are concerned with humans.
2. Restrict the search to the year prior to the last topic update or in some cases the author of the topic may specify which year range to use in the search. For new topics, the year range is restricted to the last 5 years unless the topic author provides other instructions.
3. May restrict the search to Adults only or Pediatrics only.
4. Articles consisting of only summaries or case reports are often excluded from final results.

The search strategy may be revised to improve the output as needed.

The total number of source documents identified as the result of the literature search is not known.

Strength of Evidence Key

Category 1 - The conclusions of the study are valid and strongly supported by study design, analysis, and results.

Category 2 - The conclusions of the study are likely valid, but study design does not permit certainty.

Category 3 - The conclusions of the study may be valid, but the evidence supporting the conclusions is inconclusive or equivocal.

Category 4 - The conclusions of the study may not be valid because the evidence may not be reliable given the study design or analysis.

The topic author drafts or revises the narrative text summarizing the evidence found in the literature. American College of Radiology (ACR) staff draft an evidence table based on the analysis of the selected literature. These tables rate the strength of the evidence for all articles included in the narrative text.

The expert panel reviews the narrative text, evidence table, and the supporting literature for each of the topic-variant combinations and assigns an appropriateness rating for each procedure listed in the table. Each individual panel member forms his/her own opinion based on his/her interpretation of the available evidence.

More information about the evidence table development process can be found in the ACR Appropriateness Criteria® Evidence Table Development document (see the "Availability of Companion Documents" field).

Modified Delphi Technique

The appropriateness ratings for each of the procedures included in the Appropriateness Criteria topics are determined using a modified Delphi methodology. A series of surveys are conducted to elicit each panelist's expert interpretation of the evidence, based on the available data, regarding the appropriateness of an imaging or therapeutic procedure for a specific clinical scenario. American College of Radiology (ACR) staff distributes surveys to the panelists along with the evidence table and narrative. Each panelist interprets the available evidence and rates each procedure. The surveys are completed by panelists without consulting other panelists. The ratings are a scale between 1 and 9, which is further divided into three categories: 1, 2, or 3 is defined as "usually not appropriate"; 4, 5, or 6 is defined as "may be appropriate"; and 7, 8, or 9 is defined as "usually appropriate." Each panel member assigns one rating for each procedure per survey round. The surveys are collected and the results are tabulated, de-identified and redistributed after each round. A maximum of three rounds are conducted. The modified Delphi technique enables each panelist to express individual interpretations of the evidence and his or her expert opinion without excessive bias from fellow panelists in a simple, standardized and economical process.

Consensus among the panel members must be achieved to determine the final rating for each procedure. Consensus is defined as eighty percent (80%) agreement within a rating category. The final rating is determined by the median of all the ratings once consensus has been reached. Up to three rating rounds are conducted to achieve consensus.

If consensus is not reached, the panel is convened by conference call. The strengths and weaknesses of each imaging procedure that has not reached consensus are discussed and a final rating is proposed. If the panelists on the call agree, the rating is accepted as the panel's consensus. The document is circulated to all the panelists to make the final determination. If consensus cannot be reached on the call or when the document is circulated, "No consensus" appears in the rating column and the reasons for this decision are added to the comment sections.

Not applicable

A formal cost analysis was not performed and published cost analyses were not reviewed.

Criteria developed by the Expert Panels are reviewed by the American College of Radiology (ACR) Committee on Appropriateness Criteria.

ACR Appropriateness Criteria®

Clinical Condition: Blunt Chest Trauma—Suspected Aortic Injury

Radiologic Procedure	Rating	Comments	RRL*
X-ray chest	9	Chest x-ray and CTA are complementary examinations. Both should be done.
CTA chest (noncoronary) with contrast	9	Chest x-ray and CTA are complementary examinations. Both should be done.
Aortography thoracic	8
MRA chest (noncoronary) without and with contrast	7	See statement regarding contrast in text under "Anticipated Exceptions."	O
CT chest without contrast	6	Useful to detect mediastinal hematoma when contrast is contraindicated.
US echocardiography transesophageal	5	Invasive. Suitable for bedside use.	O
MRA chest (noncoronary) without contrast	4		O
US intravascular aorta	4	Problem solving tool in the setting of invasive angiography.	O
Rating Scale: 1,2,3 Usually not appropriate; 4,5,6 May be appropriate; 7,8,9 Usually appropriate			*Relative Radiation Level

Note: Abbreviations used in the table are listed at the end of the "Major Recommendations" field.

Summary of Literature Review

Trauma ranks fifth behind cardiovascular diseases, cancer, cerebrovascular diseases, and chronic lower respiratory diseases as a cause of death in the United States. Seventy-five percent of the deaths from blunt trauma are due entirely or in part to chest injuries. Rupture of the thoracic aorta is a common cause of death following blunt chest trauma. In more than 80% of cases, rupture is through all three layers of the aorta, resulting in exsanguination and death at the accident site. Individuals who survive have maintained the adventitia intact but are at risk for subsequent complete rupture. For these near-full-thickness injuries, 30% of initial survivors will die within 6 hours and 20% within 24 hours if the diagnosis is not made and treatment instituted. With technological advancements, a spectrum of disease is now being appreciated. Small tears of the intima can now be diagnosed, but the natural history of these "minimal aortic injuries" is not yet known. Imaging may play a role in grading the severity of aortic injuries to help guide clinical management.

Pathophysiology

Traumatic injury of the aorta is thought by most investigators to result from unequal horizontal shear forces that are applied during high-speed deceleration to different parts of the thoracic aorta. During rapid deceleration, torsion and shearing forces are produced against the aorta at levels of relative immobility, mainly the aortic root, ligamentum arteriosum, and diaphragm. Injury occurs most commonly at the ligamentum arteriosum (80%) and less commonly to the ascending aorta. A mechanism involving compressive forces between anterior and posterior bony thoracic structures has also been proposed (the "osseous pinch").

Because the adventitia remains intact as a barrier to exsanguination in survivors, the most common pathologic findings are tears of the intima and media. The mediastinal hematoma associated with these injuries is therefore most commonly due to rupture of small arteries and veins in the mediastinum. Traumatic laceration of the aorta is the most common lesion seen at autopsy, although survival even from this injury has been reported. In these rare cases, a pseudoaneurysm is contained by periaortic tissue. Chronic pseudoaneurysm has been described and may present many years after the traumatic event.

Clinical Presentation

Variation in clinical presentation is the rule with thoracic aortic injuries. Patients may present in full cardiovascular collapse or complain of chest pain, midscapular pain, or shortness of breath. Almost half of patients with aortic disruption have no external signs of chest trauma. Because of the variable presentation, a high index of suspicion for traumatic rupture of the aorta must be assumed for any patient who has sustained high-speed rapid deceleration.

Chest Radiograph

Despite the advent of newer imaging modalities, the chest radiograph remains the primary screening method for detecting mediastinal hemorrhage following blunt thoracic trauma. It is included in most trauma center protocols in the initial evaluation of patients with polytrauma.

Because of the trauma setting in which chest radiographs of these patients are obtained, they are usually portable anteroposterior supine radiographs. This results in a lordotic view with a shortened focal spot-film distance, magnifying the width of the superior mediastinum and decreasing resolution. Sitting the patient upright when feasible for an anteroposterior radiograph should result in fewer falsely abnormal radiographs.

Most of the radiograph findings in aortic rupture are related to mediastinal hemorrhage rather than to the aortic injury itself. The most common chest radiograph finding, widening of the mediastinum, has been defined as a transverse distance of 8 cm from the left side of the aortic arch to the right margin of the mediastinum. It must be emphasized that the vast majority of patients with mediastinal widening do not have aortic injuries. Angiographically confirmed aortic injury is found in only 10% to 20% of these patients. Mediastinal widening has 90% sensitivity but only 10% specificity for aortic disruption.

Approximately 7% of patients with aortic rupture have a normal initial chest radiograph. A prior pilot study has also suggested that a chest radiograph and an abdominal computed tomography (CT) scan will identify most occult intrathoracic injuries, and thoracic CT may be reserved for patients with an abnormal chest radiograph or severe blunt trauma, which could safely reduce cost and radiation exposure while still diagnosing significant thoracic injuries. However, the diagnostic evaluation of patients with blunt chest trauma now includes chest CT at most facilities. CT has proven to be very sensitive for detecting aortic injury. When no mediastinal hematoma is detected on chest CT, the probability of a significant aortic injury is very low.

Thoracic Aortography

Thoracic aortography has been widely accepted as the gold standard for evaluating patients with suspected aortic injury. The aortogram establishes the diagnosis, defines the anatomy of the lesion, and, because approximately 20% of patients have multiple tears, identifies additional sites of injury. At most institutions, aortography is performed on patients who have suffered rapid deceleration injury and who have a widened mediastinum or obscure aortic knob and descending aorta on a chest radiograph, or who have indirect or direct signs of aortic injury detected by CT.

Various film sequences have been used, including anteroposterior, lateral, and oblique projections. It should be emphasized that more than one projection may be necessary to detect an aortic injury. Because acutely injured patients are in a hyperdynamic state, high contrast volumes of 60 to 70 cc rapidly injected are needed.

Computed Tomography

With the increasing availability of multidetector rows, CT is playing a more prominent and in many cases dominant role in the assessment of patients with suspected aortic injury. CT's strength lies in its ability to distinguish mediastinal blood from other causes of mediastinal widening detected on initial chest radiographs (e.g., artifacts of magnification, mediastinal fat, or anatomic variation). It has been suggested that routine CT has relatively lower, though still substantial, added diagnostic value compared with selective CT of the chest in patients with severe blunt trauma. If no mediastinal hematoma is detected on CT, the probability of a significant aortic injury is very low, and aortography is generally not needed. Studies have confirmed that patients with a negative chest CT in this setting have favorable clinical outcomes. It has also been shown that CT may be a useful diagnostic method for assessing chest trauma in forensic medicine as a supplement to autopsy.

Computed Tomographic Angiography (CTA)

With newer multidetector CT protocols and image postprocessing tools, angiographic images of the aorta and great vessels in multiple planes can be created. In addition, imaging of the aortic root with electrocardiography (ECG) gating decreases the pulsation artifact that can leave questions regarding traumatic aortic injury and require catheter-based aortography after CTA performed without ECG gating. Studies have shown high sensitivity and negative predictive value in the evaluation of suspected traumatic aortic injury when there are no signs of direct aortic injury such as an intimal flap, change in aortic contour or caliber, intraluminal irregularity, pseudoaneurysm, or intramural hematoma. Some authors have found that even in the presence of mediastinal hematoma, aortic injury is very unlikely without direct evidence of aortic injury. Others have shown a high specificity for aortic injury when such direct signs are present. Many centers have abandoned aortography in the initial evaluation of patients at risk of aortic injury and instead use CTA that has the additional advantage of visualizing other structures in the thorax, including bone fractures.

Magnetic Resonance Angiography (MRA)

Although magnetic resonance (MR) can demonstrate acute and subacute mediastinal hematoma, it currently does not have a role in the initial evaluation of the critically ill, hemodynamically unstable trauma patient. MR, however, has proven to be useful in evaluating chronic traumatic aortic pseudoaneurysms. In the setting of trauma, restricted access to critically ill patients in the MR scanner also poses a problem. Moreover, the strong magnetic field can be very limiting for those patients who require extensive monitoring and interventions such as a ventilator. However, despite these limitations, ECG-gated contrast-enhanced MRA with breath-holding can provide diagnostic images of the thoracic aorta in cooperative hemodynamically stable patients with blunt chest trauma. This procedure is most applicable for patients with significant contraindication to iodinated contrast. MR may also be a useful diagnostic tool in forensic medicine for evaluating blunt chest trauma.

Transesophageal Echocardiography (TEE)

TEE has been used in the acute trauma setting to study both the heart (for contusion) and the thoracic aorta. It appears to be much more sensitive than transthoracic echocardiography for detecting cardiac contusions.

TEE is more operator-dependent and more invasive than CT. The procedure usually requires sedation. In some patients, blind spots created by the tracheal-bronchial bifurcation may preclude adequate visualization of portions of the aortic arch. Other blind spots for TEE are the distal ascending aorta and the aortic arch vessels, sites of traumatic injury in up to 20% of patients with blunt chest trauma. When CTA must be delayed for emergent abdominal exploration, intraoperative TEE may be a useful modality to evaluate for aortic injury.

Recent studies have reported excellent diagnostic accuracy using TEE for recognizing aortic injury. This experience, however, has not been uniformly positive. Further studies are required before TEE can be recommended as part of the imaging workup in patients with blunt chest trauma.

Intravascular Ultrasound (IVUS)

The continued development of IVUS has offered an adjunct to standard transfemoral aortography. Although the routine use of IVUS is neither indicated nor practical, in a few cases it has been found to be useful in confirming or excluding thoracic aortic injury when angiographic findings are subtle or uncertain.

Summary

• The literature supports the continued use of the chest radiograph as the initial screening examination in the patient who has sustained blunt chest trauma.
• In the appropriate clinical setting and with a chest radiograph demonstrating mediastinal widening or other signs of mediastinal hemorrhage, thoracic aortography or helical chest CT is indicated.
• CTA is emerging as a very sensitive and specific examination for aortic injury and has replaced thoracic aortography as the primary aortic imaging tool in many trauma centers.
• With this expanding role for CTA, the role of IVUS and TEE is diminishing, but they may be useful in select cases.

Anticipated Exceptions

Nephrogenic systemic fibrosis (NSF) is a disorder with a scleroderma-like presentation and a spectrum of manifestations that can range from limited clinical sequelae to fatality. It appears to be related to both underlying severe renal dysfunction and the administration of gadolinium-based contrast agents. It has occurred primarily in patients on dialysis, rarely in patients with very limited glomerular filtration rate (GFR) (i.e., <30 mL/min/1.73 m²), and almost never in other patients. There is growing literature regarding NSF. Although some controversy and lack of clarity remain, there is a consensus that it is advisable to avoid all gadolinium-based contrast agents in dialysis-dependent patients unless the possible benefits clearly outweigh the risk, and to limit the type and amount in patients with estimated GFR rates <30 mL/min/1.73 m². For more information, please see the American College of Radiology (ACR) Manual on Contrast Media (see the "Availability of Companion Documents" field).

Abbreviations

• CT, computed tomography
• CTA, computed tomographic angiography
• MRA, magnetic resonance angiography
• US, ultrasound

Relative Radiation Level Designations

Relative Radiation Level*	Adult Effective Dose Estimate Range	Pediatric Effective Dose Estimate Range
O	0 mSv	0 mSv
	<0.1 mSv	<0.03 mSv
	0.1-1 mSv	0.03-0.3 mSv
	1-10 mSv	0.3-3 mSv
	10-30 mSv	3-10 mSv
	30-100 mSv	10-30 mSv
*RRL assignments for some of the examinations cannot be made, because the actual patient doses in these procedures vary as a function of a number of factors (e.g., region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as NS (not specified).

Algorithms were not developed from criteria guidelines.

The recommendations are based on analysis of the current literature and expert panel consensus.

Selection of appropriate radiologic imaging procedures for evaluation of patients with blunt chest trauma, suspected aortic injury

Gadolinium-based Contrast Agents

Nephrogenic systemic fibrosis (NSF) is a disorder with a scleroderma-like presentation and a spectrum of manifestations that can range from limited clinical sequelae to fatality. It appears to be related to both underlying severe renal dysfunction and the administration of gadolinium-based contrast agents. It has occurred primarily in patients on dialysis, rarely in patients with very limited glomerular filtration rate (GFR) (i.e., <30 mL/min/1.73 m²), and almost never in other patients. Although some controversy and lack of clarity remain, there is a consensus that it is advisable to avoid all gadolinium-based contrast agents in dialysis-dependent patients unless the possible benefits clearly outweigh the risk, and to limit the type and amount in patients with estimated GFR rates <30 mL/min/1.73 m². For more information, please see the American College of Radiology (ACR) Manual on Contrast Media (see the "Availability of Companion Documents" field).

Relative Radiation Level (RRL)

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, an RRL indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, both because of organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared to those specified for adults. Additional information regarding radiation dose assessment for imaging examinations can be found in the ACR Appropriateness Criteria® Radiation Dose Assessment Introduction document (see the "Availability of Companion Documents" field).

The American College of Radiology (ACR) Committee on Appropriateness Criteria and its expert panels have developed criteria for determining appropriate imaging examinations for diagnosis and treatment of specified medical condition(s). These criteria are intended to guide radiologists, radiation oncologists, and referring physicians in making decisions regarding radiologic imaging and treatment. Generally, the complexity and severity of a patient's clinical condition should dictate the selection of appropriate imaging procedures or treatments. Only those examinations generally used for evaluation of the patient's condition are ranked. Other imaging studies necessary to evaluate other co-existent diseases or other medical consequences of this condition are not considered in this document. The availability of equipment or personnel may influence the selection of appropriate imaging procedures or treatments. Imaging techniques classified as investigational by the U.S. Food and Drug Administration (FDA) have not been considered in developing these criteria; however, study of new equipment and applications should be encouraged. The ultimate decision regarding the appropriateness of any specific radiologic examination or treatment must be made by the referring physician and radiologist in light of all the circumstances presented in an individual examination.

An implementation strategy was not provided.

Not applicable: The guideline was not adapted from another source.

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Vascular Imaging

Panel Members: Shadpour Demehri, MD (Research Author); Frank J. Rybicki, MD, PhD (Principal Author and Panel Chair); Karin E. Dill, MD (Panel Vice-chair); Benoit Desjardins, MD, PhD; Chieh-Min Fan, MD; Scott D. Flamm, MD; Christopher J. Francois, MD; Marie D. Gerhard-Herman, MD; Sanjeeva P. Kalva, MD; Hyun S. Kim, MD; M. Ashraf Mansour, MD; Emile R. Mohler III, MD; Isabel B. Oliva, MD; Matthew P. Schenker, MD; Clifford Weiss, MD

Not stated

This is the current release of the guideline.

This guideline updates a previous version: Holtzman SR, Yucel EK, Rybicki FJ, Baum RA, Desjardins B, Flamm SD, Foley WD, Koss SA, Mammen L, Mansour MA, Narra VR, Expert Panel on Vascular Imaging. ACR Appropriateness Criteria® blunt chest trauma -- suspected aortic injury. [online publication]. Reston (VA): American College of Radiology (ACR); 2009. 5 p. [37 references]

The appropriateness criteria are reviewed biennially and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

Electronic copies: Available (in Portable Document Format [PDF]) from the American College of Radiology (ACR) Web site.

Print copies: Available from the American College of Radiology, 1891 Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

The following are available:

• ACR Appropriateness Criteria®. Overview. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the American College of Radiology (ACR) Web site.
• ACR Appropriateness Criteria®. Literature search process. Reston (VA): American College of Radiology; 1 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Evidence table development. Reston (VA): American College of Radiology; 4 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Radiation dose assessment introduction. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria® Manual on contrast media. Reston (VA): American College of Radiology; 90 p. Electronic copies: Available in PDF from the ACR Web site.

None available

This summary was completed by ECRI on February 20, 2001. The information was verified by the guideline developer on March 14, 2001. This summary was updated by ECRI on March 6, 2006. This NGC summary was updated by ECRI Institute on June 8, 2010. This summary was updated by ECRI Institute on January 13, 2011 following the U.S. Food and Drug Administration (FDA) advisory on gadolinium-based contrast agents. This NGC summary was updated by ECRI Institute on March 9, 2012.

Instructions for downloading, use, and reproduction of the American College of Radiology (ACR) Appropriateness Criteria® may be found on the ACR Web site .