Thorax 2 (Traumatic aortic injury (CT ( most common) (grading system …
Traumatic aortic injury
- MR angiography provides an excellent display of the aortic lesion and its relationship with supra-aortic vessels
- Sagittal MR image demonstrates a lesion of the isthmic aorta.
- For more than 20 years aortography has been the only imaging modality for studying aortic pathology, and it has been considered to be the gold standard in confirming or excluding the presence of traumatic aortic rupture.
- The diagnosis is based on the detection of the intimal/medial tear visible as a linear irregular filling defect within the lumen of the aorta
- can be performed quickly at the bedside.
- non-invasive technique and does not require the administration of contrast media.
- provides information on possible associated cardiac contusions or valvular lesion.
- disadvantages of transesophageal echocardiography (TEE): It cannot be performed in patients with facial fractures or cervical spine fractures,
CT ( most common)
- Comparing the diagnostic value of transesophageal echocardiography (TEE) and helical CT it found false negative value with TEE in a traumatic lesion of the innominate artery, identified by helical CT.
- On the contrary, helical CT missed few cases of intimal/medial injuries at the aortic isthmus; however, the sensitivity and specificity of helical CT in the detection of traumatic aortic lesions was approximately 100%
Grade 0: normal aorta and mediastinum
Grade 1: abnormal mediastinum and normal aorta.
Grade 2: minimal aortic injury. intimal injuries extended for 1 cm or less may be difficult to detect and should be differentiated from atherosclerotic plaques.
Grade 3: confined aortic injury. This is the most common type of aortic lesion, easily identified due to the formation of pseudoaneurysm.
Grade 4: total aortic disruption. The aortic contour is irregular, poorly defined, and contrast medium extravasation into the extra-adventitial space is visible
- if the adventitia is intact, aortic rupture may occur without hemorrhage
- signs of aortic rupture include:
an abrupt change in the aortic contour,
extravasation of contrast material from the
diminished caliber of the descending aorta
double aortic lumen.
- detects of mediastinal hematomas as an indirect sign, rather than on the detection of direct signs of aortic injury
- The hematoma secondary to aortic rupture is mostly peri-aortic and may extend along the descending aorta
- The following are the most frequent and important abnormalities seen on the plain chest radiograph :
Abnormal aortic contour
Aortopulmonary window opacification
Shift of the trachea and nasogastric tube
Widening of paraspinal lines
and of the paratracheal stripe
Depressed left mainstem bronchus
- patients with aortic rupture do not present with indicative clinical signs, the routine chest radiograph an essential tool for identifying subjects with suspected aortic injury
- Aortic rupture occurs at the isthmus in 90% of the clinical series.
- The ascending aorta may be involved in the proximity of the innominate artery or in its proximal segment superior to the aortic valve
- Other less common locations are distal segments of the descending aorta or the abdominal infrarenal segment
- a lesion of the aortic wall extending from the intima to the adventitia, as a result of a trauma
- aortic rupture is secondary only to head trauma: Air bags and seatbelts do not protect against this type of impact
- CT angiography, and MR angiography are highly sensitive and specific for the diagnosis of aortic dissection.
- Because of limitations in acquiring diagnostic images in some subjects and lower diagnostic accuracy, transthoracic echocardiography has been replaced by transoesophageal echocardiography.
- The portability of transoesophageal echocardiography is a highly attractive attribute since it can be taken to the patient in the emergency department or intensive care unit.
- The definitive diagnosis established by:
computed tomography angiograhy,
magnetic resonance imaging angiograhy,
The chest X-ray is neither sensitive nor specific
The chest radiograph demonstrates an enlarged thoracic aorta as a consequence of underlying predisposing diseases such as hypertension or aortic valvular disease.
The chest X-ray may display features indicative of Marfans syndrome such as sternal deformity, scoliosis and elongated thorax.
Infrequently, the chest X-ray may demonstrate inward displacement of intimal calcification in the aortic arch on the frontal view or an apical pleural cap.
- Splitting of the media of the aortic wall by blood. It may occur by means of a tear in the aortic intima with blood passing from the lumen into the wall causing the intima to be torn from the wall for a variable distance. Dissection may also occur by spontaneous bleeding of the vasa vasorum causing intramural haematoma without rupture of the intima and consequently no connection between the lumen and the intramural dissection.
- There are two classifications of aortic dissection. The Stanford classification recognizes Type A (involvement of ascending aorta alone or involvement of ascending and descending aorta) and Type B (involvement of descending aorta alone). The De Bakey classification describes Type I (ascending and descending aorta), Type II (ascending aorta alone) and Type III (descending aorta only). Stanford A and De Bakey I and II are treated by emergency surgery.
recommended as the procedure of choice in the patient with a suspected diagnosis of PE. Unfortunately, angiography is invasive and has achieved only limited patient and physician acceptance.
- spiral CT:
Contrast-enhanced helical CT, can directly display the emboli.
followed by additional testing if not diagnostic and a combination of CT and lower extremity Doppler ultrasonography in the remainder of patients.
Angiography would be reserved for cases where imaging results are equivocal and a strong clinical suspicion persists.
- chest film abnormalities are minor and nonspecific:
an elevated hemidiaphragm,
a small pleural effusion,
long bands of focal atelectasis (Fleischner lines)
Westermark's sign (the obstructed vessel is enlarged)
Hampton's hump (focal consolidation in the costophrenic angle)
air space consolidation
- Westermark's sign, Hampton's hump and a wedge-shaped, pleural-based density are more suggestive but uncommon manifestations of pulmonary embolus.
- partial or complete obstruction of one or more pulmonary arterial branches by a clot.
- difficult to diagnose
- often associated with lower extremity venous thrombosis.
- more than one test is required to establish a diagnosis.
- chest radiograph is the initial examination.
- majority of chest radiographs in patients with PE are abnormal.
- lower lobe:
identical to that seen with left upper lobe collapse.
major and minor fissures are both displaced downward and backward creating an opacity that obliterates the dome of the right hemidiaphragm.
- middle lobe:
collapsed right middle lobe is easily recognized on the lateral chest radiograph.
right hilum is not displaced. The right hemidiaphragm and mediastinum are in a normal position.
- right upper lobe:
right hilum becomes elevated;
collapsed lobe packs against the mediastinum and lung apex.
golden S sign
- left upper lobe:
hilum is displaced upwards and the major fissure forwards
Displacement of the anterior mediastinum fat and displacement of the trachea towards the left
left hemidiaphragm is moderately elevated
sharp lucent interface between the atelectatic lobe and the mediastinum on the chest radiograph, a phenomenon known as the Lufsichel sign
- involve one or more lobes or segments .
- can have a nonanatomical distribution.
- opacification: Air within the collapsed or atelectatic lung parenchyma can be entirely resorbed and partially replaced by fluid or fibrosis.
- signs of loss of volume:
displacement of fissures, pulmonary blood vessels and major bronchi,
shift of other structures to compensate for the loss of volume.
golden S sign: large tumour mass located in a parahilar situation may produce a bulge in the contour of the collapsed lobe (In the case of obstructive atelectasis)
- a loss of volume of lung parenchyma caused by a reduced inflation.
- mechanisms that cause atelectasis:
bronchial obstruction (most frequent)
extrinsic compression of adjacent parenchyma (pleural fluid or air)
cicatrization atelectasis resulting from lung parenchymal fibrosis;
adhesive atelectasis resulting from loss of surfactant.
- major radiological signs are opacity of the lobe and loss of volume of the lobe.
- Opacity results from the presence of intra-alveolar fluid in the case of obstructive atelectasis or passive atelectasis or from scarring or lung fibrosis in the case of cicatrization atelectasis.
- The radiograph in cardiogenic pulmonary oedema may show cardiomegaly, alteration of cardiac contour due to congenital heart disease or abnormality of the pulmonary vasculature due to a right-to-left shunt.
- The earliest radiographic change visible in increased pulmonary venous pressure is redistribution of blood flow, with an increase in prominence of the normally smaller upper lobe vessels. Also, the supine film does not allow detection of any change in distribution.
- radiographic changes of hydrostatic oedema are quite characteristic.
- As the left-sided pressure increases, the blood is diverted to the upper lobes. This results in "cephalization" with the upper lobe vessels becoming larger than the lower lobe vessels (in the normal adult, the lower lobe pulmonary vessels are larger than the upper lobe vessels due to gravitational forces)
- A great aid in evaluating cephalization is the end-on appearance of the paired pulmonary artery and bronchus of the anterior segments of the upper lobes.
- In left heart failure, the artery enlarges relative to the bronchus. Since they are in the same plane, magnification is not an issue.
- Abnormal accumulation of fluid in the interstitial compartment of the lung with or without associated air-space filling.
- due to changes in hydrostatic forces in the capillaries, to increased capillary permeability or to impaired lymphatic drainage.
- Transudative pulmonary oedema is due to increased hydrostatic pressure or, rarely, due to decreased oncotic pressure across a functioning capillary membrane.
- Hydrostatic pulmonary oedema can result from cardiogenic or noncardiogenic (renal failure, fluid overload) causes.
- Cardiogenic pulmonary oedema is a consequence of elevated left-sided pressure which may result from left ventricular dysfunction, mitral valve disease, left atrial disease or, rarely, pulmonary venous obstruction.
- The stomach, transverse colon, and omentum may herniate into the pericardium through lesions of the central tendon
- single-slice or multislice spiral CT with high-quality sagittal or coronary reconstructions has remarkably increased the sensitivity compared with unsatisfactory results of conventional CT
- Magnetic resonance is the ideal method for visualizing the diaphragm, particularly on the left side. On T1-weighted sequences, the diaphragm is hypointense thin band of soft tissue outlined by the hyperintense signal of abdominal and mediastinal fat
- Generally, the use of MR imaging is limited in those cases where spiral CT has less diagnostic doubts.
- Mostly caused by penetrating trauma. more frequently observed in abdominal traumas.
- Left-sided diaphragmatic ruptures predominate.
- Bilateral injuries are extremaly rare
- always associated with other traumatic pathologies (pleural effusions, lung injury, aortic injury, hepatic injury, splenic injury, fractures, acute gastric distension, paralysis of the phrenic nerve)
- Chest radiography is the initial and most commonly performed imaging modality
- The following radiological signs can be detected on chest radiographs:
an abnormal course of the nasogastric tube;
an elevated or intrathoracic location of abdominal organs;
obliteration, elevation, or distortion of the diaphragm;
contralateral shift of the mediastinum;
air-fluid levels in the lower thorax; and fractures of the lower ribs
- Supine chest film shows:
left hemothorax associated with pulmonary contusions
moderate right shift of the mediastinal shadow
thin curved radiopaque band caused by the interface between lung and herniated stomach
- must be excluded in any case of mediastinal penetrating trauma. Esophageal rupture is extremely rare as a complication of blunt trauma
- At CT, the presence of air bubbles in the mediastinum suggests esophageal perforation.
- Contrast esophagography is the ideal method (90% sensitivity). should be performed first with water-soluble contrast and, if no leaks are detected, with barium sulfate contrast.