TABLE 5-1.
Common Thoracic Imaging Modalities
| Modality | Applications | Radiation Exposure | Cost | Contraindications |
|---|---|---|---|---|
| X-ray (radiograph) | Broad utility in chest pain, dyspnea, fever, hemoptysis, pneumoperitoneum, foreign body, trauma | 0.01-0.02 mSv (~1 day of background radiation on Earth) | $50-$200 | None. X-ray is safe in pregnancy, with or without abdominal shielding. |
| Computed Tomography (CT) | Pulmonary embolism, aortic disease, coronary artery disease, trauma, abscesses, malignancy, further delineation of chest x-ray abnormalities | 8-20 mSv, depending on factors such as electrocardiogram gating (see Chapter 8) | $1000-$2000 | IV contrast used for CT angiography is contraindicated by renal insufficiency or allergy. Radiation dose is high, raising concerns in young patients and women due to breast exposure. |
| Ventilation-Perfusion (VQ) Scan, a nuclear scintigraphy technique | Pulmonary embolism; also used in nonemergent settings to evaluate lung ventilation | 8 mSv | $1000-$2000 | Use in pregnancy and nonpregnant women has been advocated as an alternative to CT, based on some studies showing lower radiation exposures from VQ. Use is contraindicated in patients with extensive lung disease, e.g., COPD or asthma, due to high likelihood of nondiagnostic results in PE evaluation. |
| Echocardiography | Pericardial effusion, cardiac output, valvular abnormalities, congenital heart disease, pulmonary embolism, cardiac arrest | None | $500; bedside echo by emergency physicians may or may not be billed depending on institution | None. |
| Magnetic resonance imaging (MRI) | Aortic disease, pulmonary embolism (not standard) | None | $3000-$4000 | Pacemakers and other electronic devices are a contraindication, although some devices are safe (check device- and MRI machine–specific information). Gadolinium contrast used in many chest applications is contraindicated in patients with severe renal disease. |
| Fluoroscopy | Pulmonary angiography, aortography, esophagography | 4-20 mSv; high radiation exposure due to total duration of “beam on” time | Extremely variable; may exceed $10,000 for aortography or pulmonary angiography if used for diagnosis and treatment | Radiation exposure is a relative contraindication in young patients. Injected contrast agents are contraindicated by allergy or renal insufficiency. |
| Positron Emission Tomography (PET) | Detection of metabolically active neoplastic disease | Not routinely used in emergency department patients | ||