Clinical and imaging aspects of pulmonary embolism: a primer for radiologists

Although many advancements have been made in imaging modalities that can be used to diagnose pulmonary embolism (PE), computed tomography pulmonary angiography (CTPA) is still the preferred gold standard for promptly diagnosing pulmonary embolism by looking for filling defects caused by the embolus lodged within the main pulmonary artery or its respective branches. The diagnosis is made by the radiologists in emergency settings where quick detection of a PE on CTPA helps the Pulmonary Embolism Response Team (PERT) in quick management. Thus, utmost care is needed to follow standard image acquisition protocols and optimal contrast administration techniques to achieve a contrast opacification of at least 210 Hounsfield units for the radiologists to easily pinpoint an embolus within the pulmonary arteries. Even following proper CTPA scan acquisition guidelines, a CTPA image is prone to several artifacts that can be mistaken for a PE, resulting in a false positive read. In addition to this, many incidental findings, that can be the etiology of chest pain in a PE-suspected patient, are often overlooked by emergency radiologists who try to be as quick as possible in their read so that timely management of PE can be ensued. Taking this into account, our review paper provides the audience with a comprehensive understanding of the clinical aspects of pulmonary embolism and the imaging modalities used for PE detection. The main focus is on CTPA, its acquisition protocols, and the various incidental findings and artifacts to look for while interpreting a CTPA scan. PRéCIS: Beyond the filling defects, a CTPA scan should also be assessed by the radiologists for any incidental findings while keeping in mind several associated pitfalls and artifacts of CTPA.