Diagnostic value of the helical CT scan for traumatic aortic injury: Correlation with mortality and early rupture

doi:10.1016/j.jemermed.2005.08.004

The Journal of Emergency Medicine

Volume 30, Issue 3, April 2006, Pages 277-282

https://doi.org/10.1016/j.jemermed.2005.08.004 Get rights and content

Abstract

To evaluate the value of helical computed tomography of the thorax (HCTT) as a definitive tool for diagnosing traumatic aortic injury, this study retrospectively examined 53 patients with blunt thoracic injuries and HCTT during a 5-year period. All CT scans were reviewed for direct signs of aortic injury and correlated with aortography or surgery. Correlations between clinical parameters, as well as combinations of direct signs and individual signs, and mortality were analyzed in all traumatic aortic injury (TAI) cases. Direct signs were seen on the HCTT in 25 cases and 22 had TAI. All false positive results came from the group with only a single direct sign depicted on HCTT. Among individual direct signs examined, intimal flap and luminal thrombus were the most specific (100%), whereas irregular aortic contour was the most sensitive (100%). A combination of ≥ 3 direct signs (p = 0.006) and periaortic contrast material extravasation significantly correlated with early rupture and mortality (p = 0.002). In conclusion, intimal flap on HCTT is both the most specific and sensitive sign for TAI. TAI patients with ≥ 3 direct signs, including periaortic contrast material extravasation, may not require aortography before immediate surgery.

Introduction

Traumatic aortic injury (TAI) is a potentially lethal condition. It accounts for 10–20% of mortality in high-speed deceleration accidents (1, 2). Among all victims of TAI, 80–90% die at the scene (1, 3). Of the remaining victims who arrive at the emergency department, the mortality rate of untreated TAI remains high; 30% of the mortality occurs within 6 h, 40–50% within 24 h (3, 4). However, patients receiving prompt recognition and surgery survive more than 70% of the time (4).

The diagnostic tool requirement in the Emergency Department, therefore, should be fast, timely, available, and highly specific. In recent years, helical computed tomography of the thorax (HCTT) has been advocated as a screening tool for TAI after blunt chest trauma, but its role in replacing catheter aortography as a definitive diagnostic tool remains controversial (2, 5, 6). Recently, reports showed that direct signs revealed on HCTT are specific and accurate in diagnosing TAI, and that aortography is not needed in patients with a clearly positive CT scan (7, 8, 9, 10). Despite evidence that HCTT can be as accurate and as effective as aortography, ambiguities regarding this recommendation still exist, especially in the surgical community, and some surgeons are reluctant to operate on the basis of HCTT alone. This is due in part to the perceived mandatory need for aortography before operation, and also, false positive results using direct signs have been reported (11, 12, 13). However, the requirement for aortography in patients with clearly positive CT scans may delay definite therapy and even result in death in some patients without obtaining additional information needed for surgery.

The purpose of this study was to evaluate the value of individual and combined direct signs revealed by HCTT in the diagnosis of traumatic aortic injury among patients in whom aortic injury was subsequently proven or excluded. The mortality risk correlated with these direct signs was also measured.

Section snippets

Materials and methods

During a period of 5 years, 479 patients who sustained blunt chest injuries underwent HCTT at a Level I trauma center. These patients were referred to HCTT if they presented with a significant injury mechanism that suggested deceleration injury, and chest radiographic findings of possible mediastinal hematoma. Patients whose chest radiographs did not show suspicious findings also underwent HCTT if aortic injury was suspected clinically or if contrast-enhanced helical CT scan of the abdomen or

Statistical analysis

Data are presented as means ± standard deviation (SD) or frequency (percentage). Because the sample size was small, Fisher’s exact test or the Wilcoxon rank-sum test was conducted to compare data between the mortality and surviving groups. The strength of association was presented as odds ratio (95% CI) for binary variables with survival status. All p values reported were one sided. Results were considered statistically significant if p < 0.05.

Results

Of the 53 patients, direct signs were found in 25 cases and not found in 28 cases. Among the 25 cases with direct signs revealed on HCTT, 22 had aortic injuries proved by subsequent aortography or surgical findings, and 3 did not show acute thoracic aortic injuries. Aortography in the 28 cases without direct signs was normal. None of these 31 patients died of mediastinal exsanguination during hospitalization or clinical follow-up for a median of 12.2 months. Of the 22 patients who had aortic

Discussion

Rapid exsanguination after TAI, if not promptly diagnosed and treated, is a threat to patients who survive long enough to reach a hospital. Patients with TAI often have multiple injuries and a wide range of signs and symptoms that are seldom specific (1, 6). The diagnosis of TAI is difficult, and therefore an imaging examination is critical in evaluating this injury. This imaging modality must be safe, efficient and reliable.

HCTT is an ideal imaging tool for TAI in the Emergency Department (ED)

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Traditionally, when one suspected traumatic thoracic aortic injury based on clinical and chest radiographic findings, conventional aortography was considered the diagnostic gold standard, especially in hemodynamically unstable patients. There is a growing body of evidence supporting the use of MDCT as the primary diagnostic tool in this clinical setting.4,5,73–76 Because of the early mortality with the more typical aortic injuries, atypical locations may be encountered more commonly in those who survive long enough to be evaluated with a CT scan.
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El traumatismo de aorta torácica es una lesión asociada a una alta morbimortalidad en el lugar del accidente. En los años noventa se generalizó el tratamiento mediante la colocación de un stent endovascular con buenos resultados. En este trabajo presentamos una serie de cinco casos clínicos de pacientes ingresados en la Unidad de Cuidados Intensivos de nuestro hospital durante el año 2006. De un total de 619 pacientes ingresados en el mismo periodo, 121 (19,5%) fueron traumáticos y 5 (4,13%) sufrían traumatismos de aorta torácica. Todos los pacientes fueron diagnosticados por tomografía computarizada helicoidal torácica al ingreso. Cuatro pacientes tenían un pseudoaneurisma de aorta y fueron intervenidos. Tres recibieron tratamiento endovascular dentro de las 36 primeras horas y el otro al vigesimoctavo día del ingreso. El quinto paciente presentó una lesión de la íntima y no se intervino. La evolución posterior fue buena en todos los casos.
Thoracic aorta traumatism is a lesion associated to high morbidity-mortality at the site of the accident. In the 90’s, treatment by placement of an endovascular stent was generalized with good results. In this work, we present a series of 5 clinical cases of patients admitted to the Intensive Care Unit of our hospital during the year 2006. Out of a total of 619 patients admitted in the same period, 121 (19.5%) were traumatic and 5 (4.13%) had thoracic aorta traumatisms. All of the patients were diagnosed by thoracic helical computed tomography on admission. Four patients had a pseudoaneurism of the aorta and underwent an operation. Three received endovascular treatment within the first 36 hours and the fourth on day 28 of admission. The fifth patient had a lesion of the intima and was not operated on. Posterior evolution was good in all the cases.
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As CT technology advanced, first with the introduction of helical CT, and later multi-row detector CT (MDCT), the quality of images obtained in the axial plane, multiplanar reformations, surface contour, and volume rendering techniques improved in step. Over the past decade, these advances have made CT the usual definitive screening test for major thoracic vascular injury, without the requirement of arteriography or transesophageal echocardiography to exclude or confirm the diagnosis, with the rare exception of an equivocal CT result or a technically inadequate study [9–11]. While the improved spatial resolution, better overall image quality, and supplemental post-processing techniques have been a great boon to the success of CT for the diagnosis of aortic-great vessel injury, these advances have also led to recognition of greater numbers of normal variants of vascular anatomy and subtler vascular injuries that were less likely to be appreciated using earlier conventional CT scans obtained with wider slice thickness, greater motion artifacts, poorer quality multiplanar reformations, and less consistent peak aortic contrast opacification.
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Original contributionDiagnostic value of the helical CT scan for traumatic aortic injury: Correlation with mortality and early rupture

Abstract

Introduction

Section snippets

Materials and methods

Statistical analysis

Results

Discussion

Ann Thorac Surg

Am J Emerg Med

Am J Emerg Med

Ann Vasc Surg

Ann Thorac Surg

Prospective study of blunt aortic injuryMulticenter Trial of the American Association for the Surgery of Trauma

J Trauma

Can chest CT be used to exclude aortic injury?

Radiology

Thoracic aorta injuriesmanagement and outcome of 144 patients

J Trauma

Nonpenetrating traumatic injury to the aorta

Circulation

Original contribution
Diagnostic value of the helical CT scan for traumatic aortic injury: Correlation with mortality and early rupture