American Association of Critical-Care Nurses (AACN) Certification Practice Test

Which imaging modality is considered the gold standard for diagnosing a pulmonary embolism?

1. X-ray

2. CT with contrast

3. Ultrasound

4. Chest MRI

The correct answer is: CT with contrast

The imaging modality recognized as the gold standard for diagnosing a pulmonary embolism is CT with contrast. This approach, often referred to as CT pulmonary angiography (CTPA), allows for detailed visualization of the pulmonary arteries. It is particularly effective in identifying the presence of blood clots in the pulmonary circulation, which are the hallmark of pulmonary embolism. CTPA is favored for its rapid acquisition of images and high sensitivity and specificity for detecting emboli. The use of contrast enhances the visibility of blood vessels, allowing for clearer delineation between normal and obstructed areas, making it an indispensable tool in emergency settings where prompt diagnosis is critical. While other modalities, such as X-ray, ultrasound, and chest MRI, have their respective roles in imaging the chest, they do not provide the same level of diagnostic accuracy for pulmonary embolism as CT with contrast. X-rays can help rule out other conditions but do not visualize clots effectively. Ultrasound is mainly used for assessing deep vein thrombosis, not directly visualizing pulmonary embolism. Chest MRI can be beneficial for certain patients, especially those who cannot undergo CT, but it is not the standard first-line test for this specific diagnosis.