From the Guidelines
IV contrast is recommended for chest CT scans in patients with suspected parapneumonic effusion or empyema, as it improves visualization of pleural abnormalities and aids in diagnosis. The main indications for IV contrast in chest CT scans include:
- Suspected pulmonary embolism
- Evaluation of mediastinal masses or lymphadenopathy
- Assessment of vascular structures (e.g., aorta, pulmonary arteries)
- Characterization of lung nodules or masses
- Staging of lung cancer
- Evaluation of pleural diseases, such as suspected malignant pleural effusion or unilateral pleural effusion with an increased pretest probability of malignancy 1 Typically, 80-100 mL of iodinated contrast material is administered intravenously at a rate of 3-4 mL/second. The scan is timed to capture images during the appropriate phase of contrast enhancement, usually 25-30 seconds after injection for pulmonary arterial phase and 60-70 seconds for venous phase. Acquiring the CT scan 60 seconds after the contrast bolus improves visualization of pleural abnormalities associated with malignancy 1. Before administering contrast, ensure the patient has adequate renal function (eGFR >30 mL/min/1.73m²) and no history of severe allergic reactions to iodinated contrast. Patients should be well-hydrated and instructed to inform the technologist of any unusual sensations during injection. IV contrast improves visualization by increasing the density difference between vascular structures and surrounding tissues, allowing for better delineation of anatomy and pathology. This enhanced visibility is crucial for accurate diagnosis and characterization of various thoracic conditions. In patients with recent pneumonia and suspected parapneumonic effusion or empyema, CT chest with IV contrast is recommended, as it can accurately identify pleural enhancement, pleural thickening, loculation, extrapleural fat proliferation, and increased attenuation of the extrapleural fat, which are associated with the diagnosis of empyema 1. The use of IV contrast may also improve detection of mediastinal and hilar adenopathy, distinguishing nodes from mediastinal vessels, and aid in delineation of soft tissue extension of skeletal metastatic disease 1.
From the FDA Drug Label
Computed Tomography of the Head or Body (270 mg Iodine/mL and 320 mg Iodine/mL) Coronary Computed Tomography Angiography (CCTA) (320 mg Iodine/mL) The indications for Intravenous (IV) Contrast in Computed Tomography (CT) scans of the chest are:
- Computed Tomography of the Head or Body: to assist in diagnostic evaluation
- Coronary Computed Tomography Angiography (CCTA): to assist in the diagnostic evaluation of patients with suspected coronary artery disease 2
From the Research
Indications for Intravenous (IV) Contrast in Computed Tomography (CT) scans of the chest
The use of IV contrast in CT scans of the chest is indicated in various situations, including:
- Evaluation of vascular structures, such as in the assessment of pulmonary embolism 3, 4, 5
- Detection of nodal, pleural, and pulmonary disease in oncology patients 4
- Assessment of pleural abnormalities and pulmonary masses 4
- Diagnosis of unsuspected pulmonary embolism in routine chest CT scans 3, 5
Contrasting Phases
Different contrasting phases have been studied, including:
- Arterial phase: commonly used for CT angiograms, but may not provide optimal enhancement for nodal, pleural, and pulmonary assessment 4
- Venous phase: demonstrated to provide more consistent enhancement of vessels, higher attenuation of nodes, pulmonary and pleural lesions, and reduced perivenous beam hardening artefact 4
Safety and Guidelines
Updated guidelines for IV contrast use in CT and MRI scans have been published, indicating that IV contrast can be used safely in more patients, with fewer precautions than previously recommended 6