Scholarly article on topic 'Acute traumatic injuries of thoracic aorta: Role of 64-MDCTA in diagnosis and management'

Acute traumatic injuries of thoracic aorta: Role of 64-MDCTA in diagnosis and management Academic research paper on "Clinical medicine"

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{ATAI / MVC / EVR / ICT / LSCA / MDCTA / MPR / MPCR / MRI / VR / Acute / Thoracic / Aorta / Injury / MDCTA / Endovascular}

Abstract of research paper on Clinical medicine, author of scientific article — Fady Elganayni, Wael Abdulghaffar, Hala Aly Saleh, Ahmed H. Abou-Issa, Osman Abouelcibaa, et al.

Abstract Objectives Review our experience with 64-MDCTA in diagnosis and management of patients with acute traumatic injury of thoracic aorta. Patients and methods Thirty-five patients with possible traumatic aortic injury were subjected to 64-MDCTA. Arterial and delayed phases were acquired for chest, abdomen and pelvis. Positive findings were encountered in 24 patients, surgical repair done for 7 cases, endovascular repair for 14 cases and follow up for 1 case. Two patients died before intervention. The remaining 11 patients had no direct signs of ATAI and their follow up was uneventful. All cases planned for EVR were subjected to conventional aortography as part of the treatment process. MDCTA findings were compared with surgical, aortography findings and clinic-radiologic follow up. Results Direct positive MDCTA findings in 24 cases included pseudoaneurysm (23), transection (15), intimal tear (12), intimal flap (10), intramural–intraluminal hematoma (1) and active bleeding (3). Mediastinal hematoma as an indirect sign was detected in all cases. MDCTA findings correlated well with surgical and aortography findings. Conclusion Stable patients with potential ATAI should be subjected first to urgent MDCTA. This will offer rapid reliable diagnosis, plan intervention and avoid invasive aortography that will be indicated only if endovascular repair is decided.

Academic research paper on topic "Acute traumatic injuries of thoracic aorta: Role of 64-MDCTA in diagnosis and management"

The Egyptian Journal of Radiology and Nuclear Medicine (2012) 43, 203-210

Egyptian Society of Radiology and Nuclear Medicine The Egyptian Journal of Radiology and Nuclear Medicine

www.elsevier.com/locate/ejrnm www.sciencedirect.com

ORIGINAL ARTICLE

Acute traumatic injuries of thoracic aorta: Role of 64-MDCTA in diagnosis and management

Fady Elganayni a, Wael Abdulghaffar a, Hala Aly Saleh b,

Ahmed H. Abou-Issa a'*, Osman Abouelcibaa c, Mohammad Bafaraj d,

Mohammad Atef Bayomie

a Medical Imaging Department, Mansoura University, Egypt b Medical Imaging Department, Zagazig University, Egypt c Vascular Surgery Department, Al-Minia University, Egypt d Vascular Surgery Department, Alnoor Specialist Hospital, Saudi Arabia e Vascular Surgery Department, Al-Azhar University, Egypt

Received 2 August 2011; accepted 28 December 2011 Available online 25 January 2012

KEYWORDS

Acute;

Thoracic;

Aorta;

Injury;

MDCTA;

Endovascular

Abstract Objectives: Review our experience with 64-MDCTA in diagnosis and management of patients with acute traumatic injury of thoracic aorta.

Patients and methods: Thirty-five patients with possible traumatic aortic injury were subjected to 64-MDCTA. Arterial and delayed phases were acquired for chest, abdomen and pelvis. Positive findings were encountered in 24 patients, surgical repair done for 7 cases, endovascular repair for 14 cases and follow up for 1 case. Two patients died before intervention. The remaining 11 patients had no direct signs of ATAI and their follow up was uneventful. All cases planned for EVR were subjected to conventional aortography as part of the treatment process. MDCTA findings were compared with surgical, aortography findings and clinic-radiologic follow up. Results: Direct positive MDCTA findings in 24 cases included pseudoaneurysm (23), transection (15), intimal tear (12), intimal flap (10), intramural-intraluminal hematoma (1) and active bleeding

* Corresponding author. Tel.: +966 25667623; fax: +966 25664314. E-mail address: ahmharon@yahoo.com (A.H. Abou-Issa).

0378-603X © 2012 Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V. All rights reserved.

Peer review under responsibility of Egyptian Society of Radiology and

Nuclear Medicine.

doi:10.1016/j.ejrnm.2011.12.010

(3). Mediastinal hematoma as an indirect sign was detected in all cases. MDCTA findings correlated well with surgical and aortography findings.

Conclusion: Stable patients with potential ATAI should be subjected first to urgent MDCTA. This will offer rapid reliable diagnosis, plan intervention and avoid invasive aortography that will be indicated only if endovascular repair is decided.

© 2012 Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier B.V.

All rights reserved.

1. Introduction

Acute traumatic aortic injury is a serious outcome of blunt chest trauma; the morbidity and mortality are historically greater than 95% if the injury is left untreated. Approximately 80-90% of all ATAIs are immediately fatal. With improved detection and treatment, however, patients who initially survive are more likely to undergo successful treatment. But even among those who reach the hospital alive and are treated, the overall mortality remains greater than 30%. This figure

emphasizes the necessity of rapid and accurate detection and triage (1,2).

Ninety percent of thoracic aortic injuries occur in the region of the aortic isthmus, just distal to the origin of the LSCA. In rare cases, aortic injuries affect the descending aorta at its diaphragmatic hiatus. Thoracic aortic injury involves the ascending aorta in only 5% of the cases and is associated with grave complications, such as aortic valve rupture, coronary artery laceration and hemopericardium with cardiac tamponade. The mechanism of injury at the aortic isthmus is likely due to shearing forces during rapid deceleration between the relatively mobile aortic arch and the relatively fixed descending aorta (3,4).

Imaging evaluation of patients with potential ATAI includes plain X-ray chest, CT scan and aortography. Other modalities like MRI, intravascular US and transesophageal echoaortography are not used routinely in the assessment of ATAI (5).

1.1. Aim of the study

Show the role of 64-MDCTA in the diagnosis and management of patients with ATAI and to demonstrate CT pitfalls to avoid unnecessary aortography or intervention.

Table 1 The MDCTA findings in 24 cases.

MDCTA diagnosis* No.

Pseudoaneurysm 23

Intimal flap 10

Transection 15

Tear 12

Intramural/intraluminal hematoma@ 1

Active bleeding 3

* Patients usually have mixed lesions. @ This patient was subjected to conservative management (Fig. 3).

Figure 1 Acute injury of thoracic aorta. (A & B) Axial images at isthmus and proximal DA show disruption, intimal flaps, mediastinal hematoma (arrows), bilateral hemothorax and LT ICT. (C) Oblique MPCR shows focal bulge, extent of injury and relation to LSCA. Patient survived surgical repair.

Figure 2 Acute injury of proximal descending thoracic aorta. (A) 3D VR shows pseudodiverticulum of proximal DA with acute inferior angle. (B) Axial image shows irregular aortic contour, focal disruption and periaortic hematoma (arrows). These findings help differentiation from ductus diverticulum which usually has smooth uninterrupted margins and gentle appearing slope inferiorly.

2. Material and methods

This prospective study was conducted in a level 1 trauma center between October 2008 and October 2011. Thirty-five patients in whom ATAI was suspected on clinical and chest X-ray basis were referred for MDCTA. Mechanism of injury was MVC (33), fall from height (1) and pedestrian injury (1). Supine X-ray chest on backboard was done for all the patients.

All patients subjected to MDCTA using 64-dectector scanner (CTV, GE Healthcare). Pan CT technique for polytrauma patients was used, this includes plain CT for head and cervical spine and contrast enhanced scan for chest, abdomen and pelvis. For patients with suspected ATIA, we did 2 phases; early phase with peak arterial enhancement to obtain angiographic-like images and to allow precise localization of bleeding source if present. A delayed phase 60-70 s after contrast injection was obtained for better evaluation of non arterial injuries such as liver, spleen, kidneys, etc.

The arterial phase was done with 64 x 0.6 mm collimation, rotation time 0.4 s, pitch 1.375, tube voltage 120 kVp, and

automatic mA (tube current modulation). 100-120 ml of non-ionic iodinated contrast material (Omnipaque or Xenetix 350 mg/ml) was injected by a power injector at 4-5 ml/s through an 18 gauge cannula. 40-50 ml saline chaser followed contrast with the same rate. An automatic triggering system (Smartprep, GE Healthcare) with ROI placed in ascending aorta was initiated 10 s after the start of contrast injection. On reaching a predefined enhancement level (120HU), data acquisition from thoracic inlet to symphysis pubis starts. Raw data were reconstructed into 2.5 mm axial, sagittal and coronal images. Curved multiplanar reconstruction (CMPR) and volume rendering (VR) were also done. Interactive assessment using cross-linked images in different planes (axial, sagittal, coronal or oblique), different format (2D & 3D) and different window settings was done for all patients to offer precise anatomic details for aorta and major branches and localize the exact source of contrast extravasation if present. If EVR is decided, further dimensions and angles are measured to choose stent size, decide position of landing zone, LSCA coverage, access side for delivery system and C-arm angle during procedure.

Figure 4 Severe ATAI in 32 years old male. (A & B) Arterial phase, axial images show transection of DA (arrow in A), periaortic hematoma, bilateral hemothorax and marked attenuation of aortic lumen (arrow in B). (C & D) are the delayed phase, (C) axial image at same level of B, (D) coronal reformat. They show extensive aortic dissection (arrows) that extends to the abdominal aorta. Large periaortic contrast extravasation denotes high rate of bleeding. Patient died before intervention.

The delayed phase was obtained with 64 x 5 mm collima-tion, started 60-70 s after contrast injection to have better assessment of organs and degree of contrast extravasation if present.

3. Results

Thirty-five patients with clinical or radiographic findings suggestive of ATAI underwent MDCTA, 24 showed positive direct findings; they were 23 males and 1 female, their age ranged from 16 to 62. The cause of trauma was head-on MVC (27), side impact MVC (6), fall from height (1) and pedestrian injury (1). Direct signs for ATAI were pseudoaneu-rysm (23 cases), transection (15 cases), intimal flaps (10 cases), intimal tear (12 cases), intraluminal/mural thrombus (1 case) and active contrast extravasation (3 cases) (Table 1).

Intimal flap presented on MDCTA as linear or wavy intra-luminal filling defect (Fig. 1), intimal tear appeared as partial mural interruption with contour irregularity (Fig. 2), pseudo-aneurysm or pseudodiverticulum appeared as focal irregular contrast filled bulge from aorta (Fig. 2), mural and intralumi-nal thrombus as non-enhancing mural or intraluminal density (Fig. 3), transection appeared as near complete disruption of the whole circumference of the aorta (Fig. 4), aortic dissection which is a rare sequela of trauma appeared as a longitudinal tear in the aortic wall (Fig. 4), active bleeding appeared as extra-vascular, peri-aortic contrast leak (Fig. 5). Mediastinal hematoma appeared as soft tissue density replacing the normal fat density of the mediastinum, it was considered a secondary sign or associated finding, but alone was not considered diag-

nostic for aortic injury (Fig. 6). Although all patients were subjected to supine chest X-ray, we relied on MDCTA due to false positive and negative findings on chest X-ray. Table 2 shows the management plan according to CT diagnosis.

Before the introduction of EVR in our institution, surgical repair was the treatment option; it was done in 7 patients. No one was subjected to aortography before surgery. The position of proximal clamp was based on MDCTA reformat. Resection of the injured segment and the placement of a Dacron graft was performed through left thoracotomy. All patients survived the surgery however, 2 died during post-operative care. Operative findings correlated well with MDCTA findings.

Conventional aortography was done in 14 patients for whom EVR was the treatment option. The aortographic findings correlated with the MDCTA findings in all cases however, active contrast extravasation was appreciated better on MDCTA probably due to lower sensitivity of aortography or due to cessation or decreased rate of bleeding during the interval between MDCTA and aortography (Fig. 5).

Isthmus and adjacent DA were the most common locations for aortic injuries in our series (21 cases). Isolated descending aortic lesion was noted in 3 cases.

Among the 11 cases with negative CTA; there were pitfalls in 5 cases. These included pericardial sleeve in 2 cases (Fig. 7), thymus density in 1 case, and streak artifacts in 2 patients. In the remaining 6 cases, there was mediastinal and periaortic hematoma but direct signs for aortic injury were absent.

(Fig. 6).

Associated injuries in the 24 cases included cranial injury (12), fracture spine (14), fracture ribs (22), liver (12), spleen

Figure 5 Acute traumatic injury of proximal DA. (A & B) MDCTA shows acute injury of DA with active bleeding (arrow), focal disruption of aortic wall and irregular contour. Other signs include mediastinal hematoma, bilateral hemothorax and pulmonary hemorrhage. Patient becomes unstable which mandated urgent EVR. (C) Aortography through RT brachial artery shows extent of aortic injury however, active bleeding was not appreciated. Stent position is verified before release (arrows). (D) After deployment, the injured segment is excluded without evidence of endoleak. Patient's hemodynamics stabilized after EVR. (E) Axial CT brain shows associated right frontal intracerebral hemorrhage and subgaleal hematoma. Heparin free EVR was planned to avoid further bleeding.

(13), mediastinal hematoma (24), hemothorax (24), bowel (2) and IVC (1).

4. Discussion

Traumatic aortic injuries are time sensitive events, carry a high mortality rate and are immediately fatal in an estimated 80-90% of all cases. Although the clinical presentation or mechanism of injury is of primary importance in the prompt diagnosis of patients with ATAI, the radiologic findings play a vital supportive role (3,6,7).

CT scan is the definitive radiographic study in most patients with trauma. CT imaging of the head, chest, abdomen and pelvis is the most sensitive and accurate noninvasive diagnostic tool for identifying soft-tissue injury (8,9). However, over reliance on CT imaging can be detrimental if emergent operations are delayed. One review of patients presenting with hypotension (systolic BP < 90 mm Hg) and significant abdominal injury demonstrated greater mortality if surgery was delayed by a CT scan (10). We have 2 patients who died before intervention due to unstable hemodynamic state.

CT scanning is replacing aortography as the state-of-the-art study for imaging mediastinal vascular structures, particularly the aorta. It is also more sensitive than AP chest radiography in the detection of pneumothorax, rib fractures, pulmonary contusion, and hydrothorax. For most patients with trauma, CT scans of the head, chest, abdomen, and pelvis are sufficient

to guide operative and nonoperative management of injuries in their respective regions of the body (11,12).

As the quality of CT scans continues to increase, the role of angiography continues to focus to a greater degree on interventions rather than on diagnosis (13). In most of the centers, MDCT is now considered the diagnostic modality of choice for ATAI (14). MDCTA is particularly convenient in patients with polytrauma who are undergoing other CT scan studies at the same time. Acquisition parameters and protocols should be developed locally, based on equipment, physician preference, and patient condition (7).

ATAI may be diagnosed from CT scans on the basis of direct or indirect signs. Direct signs (e.g., aortic intimal flap, contour abnormality) are more accurate than indirect signs (e.g., mediastinal, periaortic hematoma) (7).

In our study; direct signs of ATAI on MDCTA included pseudoaneurysm in 23 cases, transection in 15 cases, intimal tear in 12 cases, intraluminal hematoma in one case and inti-mal flaps in 10 cases. The constant finding in these cases was mediastinal hematoma which was considered an indirect sign. Pseudoaneurysms presented on MDCTA as focal irregular contrast filled bulge from the aorta, transection appeared as near complete disruption of the whole circumference of the aorta, intimal tear appeared as partial mural interruption with contour irregularity, intimal flap was linear or wavy intralumi-nal filling defect, mural and intraluminal thrombus appeared as non-enhancing mural or intraluminal density. Mediastinal

Figure 6 RTA victim with mediastinal hemorrhage and possible aortic injury. (A & B) Axial CT in arterial and delayed phases show periaortic hematoma and contrast extravasation anterior to DA (thin arrows). (C) Sagittal oblique images acquired during interactive cross linked image analysis confirmed intact outline of aorta and absent direct signs of aortic injury. Block arrow in A & C indicates left intercostal artery. Patient evolved favorably, follow up CT confirmed absent aortic injury.

hematoma appeared as soft tissue density replacing the normal fat density of the mediastinum.

Many diagnostic pitfalls are encountered with the use of MDCTA in ATAI that may lead to false positive results and can be due to either anatomic or technical causes. Normal anatomic structures that may simulate ATAI include normal pericardial recesses, the left brachiocephalic vein, the left inferior pulmonary vein, the left superior intercostal vein, the right atrial appendage, and normal thymus (14). Occasionally, the take-off of bronchial and intercostal arteries can have small infundibula that may give the impression of a small pseu-doaneurysm. Infundibula are typically conical in shape and the artery can be seen at the apex of the outpouching. Ductus remnants may present as either bumps or diverticula. Occasionally, normal post-isthmic aortic dilatation (aortic spindle) may be seen when viewed in the sagittal oblique plane. This contour change is a normal finding and should not be misinterpreted as an aortic injury.

In our institution, surgery was the treatment option for patients with ATAI before the availability of EVR. With the introduction of EVR; MDCTA gained higher importance because it provides not only a rapid, reliable diagnosis but also provides a roadmap for EVR. The diameter and length of proximal landing zone, diameter of distal landing zone, and length of injured segment are measured to select suitable stent

dimensions. The relation to LSCA and possibility of coverage is also determined. The optimum C-arm angle used during intervention is predefined on MDCTA so we can reduce radiation exposure, contrast load and overall procedure time of EVR. The access and pathway of the stent is verified by examining distal aorta, iliac and common femoral arteries (Fig. 8). Other injuries like cerebral hemorrhage or other bleeding sources are checked to avoid heparin during the procedure or prioritize management actions. MDCTA was also utilized in the follow up of patients after EVR.

In conclusion; MDCTA is considered an imaging modality of choice for screening patients with potential ATAI as well as

Table 2 CT findings and management plan in 35 cases with suspected ATAI.

Finding No. Management No.

Negative MDCTA 11 None 11

Positive MDCTA 24 Surgery 7

EVR 14

Follow up 1

Death before intervention 2

Total 35 35

Figure 7 This patient referred from other hospital for EVR. 64-MDCTA done for planning, (A & B) shows the superior pericardial recess (arrows) simulating mediastinal hematoma. Left rib fracture and hemothorax are noted. (C) 3D VR shows smooth aortic contour. Follow up was uneventful.

Figure 8 EVR planning. (A) 2D MPCR shows diameter (D = 19 mm) and length (L = 8 mm) of proximal landing zone (segment between red dashed lines), the LSCA will be covered. CT scan is crucial in determining stent size and LSCA coverage before EVR. (B) Axial image at proximal landing zone shows measurement of C-arm angle prior to EVR. It is the acute angle (A) between line 1 (bisects patient) and 2 (perpendicular to the flow lumen which is represented by dashed red arrow). (C) Axial CT scan at pelvis shows post-traumatic stenosis of RT external iliac artery, compared to left one (arrows). The right side is not a suitable access for delivery system of the stent.

for other associated injuries. It is a quick, non invasive technique with high sensitivity and high negative predictive values. It provides angiographic-like images that help avoid invasive aortography and provides the roadmap for endovascular repair.

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