<< An Evidence Based Thoracic Imaging Curriculum for Emergency Medicine

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Mediastinal widening is present when the mediastinum measures greater than 8 cm at the aortic arch or the mediastinum:chest width ratio is greater than 0.25.
In the setting of trauma, serial CXR's may be indicated when suspicion is high and initial screening radiographs are negative.
The American College of Radiology rates specialized rib views as having a low level of appropriateness for adults less than 65 years of age who have sustained chest trauma and possible rib fracture(s). However, the chest radiograph is appropriate at any age when the diagnosis of rib fracture is under consideration, primarily to rule out associated pulmonary injury.
Ultrasonography has been shown to have greater sensitivity in detecting chest wall fractures than either clinical acumen or radiography.
Ultrasonography can detect hemothoraces not evident on CXR, and is rapid and accurate.
As follow up for an abnormal CXR, computed tomography of the chest has a sensitivity of 100% and specificity of 99.7%.
Myocardial contusion is best diagnosed by transesophageal echocardiography. There are no complications related to the procedure and high quality images are generally obtained.
In the setting of penetrating trauma to the heart or lung, evaluation for pericardial hemorrhage is best carried out by echocardiography. The best view is the subcostal view in which blood will appear as an anechoic area surrounding the heart.
CT has been shown to have sensitivity and specificity of 100% after suspected esophageal perforation.
On CT, the combination of discontinuity, thickening, and segmental non-recognition is reported to be 100% sensitive for diaphragmatic injury.
With 16-slice multidetector-row CT scanners, now commonly available, the entire chest can be imaged with excellent resolution, requiring a breath-hold of less than 10 seconds. These scanners can reliably diagnose tiny emboli in sub-segmental vessels, although the clinical significance of sub-segmental emboli is still in question.
With advanced generation scanners, it now appears feasible to use clinical risk stratification, D-dimer measurement, and multi-detector CT scanning to reliably and safely diagnose or exclude clinically significant pulmonary emboli.
Chest radiography has been recommended for febrile children (temperature greater than 38 C or 100.4 F) younger than three months with evidence of acute respiratory illness. However, the chance of a positive chest radiograph in a febrile infant less than three months of age with no pulmonary signs or symptoms is only approximately 1%.
The typical radiological presentation of post-primary tuberculosis in adults is with infiltration nodules in the upper zones, with or without cavitation.
CT may be better at defining the cause of hemoptysis than bronchoscopy and the two modalities are equally effective at determining the site of bleeding.
Non-contrast CT is easy, fast, and 100% sensitive for upper esophageal foreign bodies. It should be the first choice for diagnostic imaging of suspected upper esophageal foreign bodies not expected to be visible on plain radiographs.
In the acute or exudative phase of acute respiratory distress syndrome (ARDS), CXR findings include bilateral, patchy, asymmetrical pulmonary infiltrates. There may be associated pleural effusions. The pattern is indistinguishable from cardiogenic pulmonary edema.
High-resolution images obtained rapidly by multi-detector computed tomography have recently improved image quality to the point where it is possible to consider non-invasive coronary angiography as a routine clinical tool.
Echocardiography performed by emergency physicians has been shown to be a reliable technique for evaluating for pericardial effusion.
The CT scan has become a standard test for aortic dissection. In fact, multi-slice CT scanning now appears to be the modality of choice for complete examination of the entire aorta.