What is the preferred initial test for diagnosing pulmonary embolism (PE)?

The preferred initial test for diagnosing pulmonary embolism (PE) is spiral CT, also known as CT pulmonary angiography. This imaging modality is specifically designed to visualize the pulmonary arteries and can promptly and accurately identify or exclude significant clots in these vessels. The high sensitivity and specificity of spiral CT for PE make it a cornerstone in the diagnostic evaluation of patients suspected of having this condition.

In practice, a spiral CT can provide comprehensive information about the presence of emboli and any associated changes in the lung tissue. It is readily available and can be performed quickly, which is crucial given that timely diagnosis and treatment are vital for improving outcomes in patients with PE.

While other tests, such as D-dimer, chest X-ray, and leg ultrasound, can be part of the diagnostic workup, they serve different roles. The D-dimer test is useful in ruling out PE in low-risk patients but cannot definitively diagnose it. A chest X-ray may be performed to exclude other causes of chest pain or dyspnea but does not provide conclusive evidence for PE. An ultrasound of the legs is primarily used to detect deep vein thrombosis (DVT), which can be a source of emboli, but it doesn't directly assess the pulmonary vasculature