REVIEW Clinical Validity of a Negative Computed Tomography Scan in Patients With Suspected Pulmonary Embolism A Systematic Review

THE OPTIMAL DIAGNOSTIC IMAG-ing modality for acute pulmo-nary embolism continues to bedebated. Computed tomogra-phy (CT) is readily available atmost in-stitutions and is rapidly becoming the first-line imaging test for the assess-ment of patients with suspected acute pulmonary embolism.1,2 However, con-ventional single-slice spiral CT has in-sufficient sensitivity3-5 for isolated pe-ripheral pulmonary embolism. The clinical importance of detecting and treating peripheral pulmonary embo-lism remains uncertain.However,many patients with negative CT scans re-ceive additional imaging tests to de-finitively rule out a diagnosis of pul-monary embolism. The additional tests increase a patient’s exposure to radia-tion and risk of complications,6,7 and in-crease societal health care costs. The most reliable method to deter-mine the accuracy of a diagnostic test to rule out a disease is to perform a pro-spective study inwhich a diagnostic cri-terion with a high negative predictive value (NPV) is used. Although pulmo-AuthorAffiliations:DepartmentofRadiology(DrsQuiroz