Management of suspected acute pulmonary embolism in the era of CT angiography: a statement from the Fleischner Society.

During the past decade, the contribution of computed tomographic (CT) angiography in the diagnosis of pulmonary embolism (PE) has dramatically increased as a consequence of major advances in CT technology. The question now no longer concerns demonstrating its clinical value but optimizing its use in various categories of patients. Since the introduction of multidetector CT with high spatial and temporal resolution, CT angiography has become the method of choice for imaging the pulmonary vasculature when PE is suspected in routine clinical practice. This change in the imaging algorithm has had numerous practical consequences. The widespread availability of a noninvasive and accurate means of evaluating the pulmonary circulation has led to the recognition that acute PE has a lower prevalence than it was thought to have in the past among patients clinically suspected of having the disease. Because CT images contain additional diagnostic information in the majority of patients who are suspected of having acute PE and may therefore lead to diagnosis of alternative causes for the patient’s symptoms, the increased use of CT has improved patient care by minimizing diagnostic delays that may be incurred when alternative imaging tests are used. The current possibility of performing electrocardiographically (ECG)-gated examinations of the entire thorax has further reinforced the role of CT angiography in this clinical setting, adding coronary artery disease to the list of alternative diagnoses detectable with the aid of this tool and enabling the use of CT angiography to provide prognostic information from the same data set as that used to help diagnose acute PE. However, the increasingly frequent use of CT has raised concerns about the overall radiation exposure to the population scanned and has imposed on the radiology community a need to optimize scanning protocols. This, in turn, makes it necessary to stratify more precisely the population being scanned according to the likelihood of PE being present (pretest probability), with the aim of reducing the number of unnecessary CT pulmonary angiograms being obtained in patients who are unlikely to have PE. Furthermore, although the number of indeterminate studies has dramatically decreased over time because of improved CT technology, clinicians may still face diagnostic dilemmas when the CT angiographic results are either inconclusive or discordant with the pretest probability. Because of changes in strategy over the past few years and the numerous issues still being debated, the Fleischner Society has deemed it useful to propose a consensus update on the role of CT angiography in the diagnostic approach to PE in 2007.