CTA Chest with IV Contrast vs Without and With IV Contrast
CTA chest with IV contrast is the preferred imaging modality for most clinical scenarios requiring vascular imaging of the chest, while CTA chest without and with IV contrast generally provides no added diagnostic value and should be avoided.
Indications for CTA Chest with IV Contrast
- CTA chest with IV contrast is the recommended imaging modality when there is clinical concern for pulmonary embolism or aortopathy 1
- For patients with suspected malignant pleural effusion or suspected unilateral pleural effusion with increased pretest probability of malignancy, CT chest with IV contrast is recommended, with acquisition 60 seconds after contrast bolus to improve visualization of pleural abnormalities 1
- In hemodynamically stable patients with penetrating thoracic injuries, CTA chest with IV contrast is valuable for assessment of transmediastinal injury and can guide immediate surgical intervention versus expectant management 1
- For patients with hemoptysis, CT with IV contrast or CTA is recommended as it is superior to chest radiography for identifying the etiology and location of bleeding, with a localization rate of up to 91% of cases 2
Limitations of CTA Chest Without and With IV Contrast
- Performing CT chest without and with IV contrast does not provide added value compared to CT chest with IV contrast in the evaluation of complicated pneumonia 1
- There is no relevant literature supporting the use of CT chest without and with IV contrast for imaging patients with suspected lung cancer recurrence 1
- There is no relevant literature to support the use of CT chest without and with IV contrast in the initial imaging of dyspnea, cough, or chest pain with suspected noninfectious pleural effusion 1
- There is no relevant literature regarding the usefulness of adding a noncontrast phase to a contrast-enhanced CT chest for initial evaluation of penetrating torso trauma limited to the chest 1
Technical Considerations
- IV contrast significantly improves visualization of mediastinal structures and provides substantial benefit for preprocedural planning if intervention becomes necessary 2
- Patients who had CT without IV contrast before bronchial artery embolization had higher rates of emergent surgical resections following embolization (10%) compared to those who had CTA (4.5%), emphasizing the importance of IV contrast 2
- Low tube voltage protocols (80-100 kV) with reduced contrast volume can maintain adequate diagnostic quality while decreasing radiation dose exposure and preserving renal function 3
- For carotid and cerebral CTA, combining low voltage (80 kV) with 50% reduction in contrast volume can provide good image quality with lower radiation dose 4
Special Clinical Scenarios
Pulmonary Embolism Evaluation
- CTA chest with IV contrast is useful in identifying pulmonary emboli when there is a high clinical index of suspicion 1
- Small pleural effusions are present in up to 40% of PE cases, with 80% of PE-related effusions being exudates and 80% being bloodstained 5
Trauma Assessment
- CT chest with IV contrast is established as the imaging modality of choice for characterizing penetrating thoracic injuries, with a high negative predictive value up to 99% in triaging hemodynamically stable patients 1
- CTI (CT with IV contrast) and CTA are similar at evaluating trauma patients for blunt aortic injury, although CTI may be preferable during initial assessment as contrast injection may be combined with abdominal scanning 6
Hemoptysis Workup
- The American College of Radiology recommends CT with IV contrast for all patients with frank hemoptysis, hemoptoic sputum, or risk factors for lung cancer 2
- High-resolution CT (HRCT) identified a cause of hemoptysis in 41% of patients with a normal chest radiograph, but modern CT technology can now reconstruct HRCT-quality images from routine CT scans with IV contrast 2
Common Pitfalls to Avoid
- Using CTA for suspected pleural effusion or lung abscess when timing of dedicated CTA studies is suboptimal for evaluation of pleural enhancement that is most conspicuous in the delayed phase 1
- Performing non-contrast CT of the chest in trauma patients, which is inadequate to definitively evaluate for vascular injuries in the setting of ballistic trauma 1
- Neglecting to use IV contrast in patients with hemoptysis, which significantly improves diagnostic yield and preprocedural planning if intervention becomes necessary 2
- Overlooking the potential for reduced contrast protocols that maintain diagnostic quality while decreasing radiation exposure and contrast volume 7, 3