Computed tomographic pulmonary angiography: clinical implications of a limited negative result.

LESS ISMORE Computed Tomographic Pulmonary Angiography: Clinical Implications of a LimitedNegative Result A substantial proportion of computed tomographic pulmonary angiography (CTPA) results are degraded by patientrelated and technical factors, yielding a limited negative interpretation, which qualifies the definitive exclusion of pulmonaryembolism.This leads todiagnosticuncertaintyand may affect patient management. A multicenter randomized clinical trial ofCTPAvsventilation-perfusionscintigraphyconsideredCTPA results negative if no pulmonary embolismwas demonstrated to the lobar level.1 Investigators have explicitly questioned the clinical relevance of small pulmonary emboli,2,3 and there is growing concern that pulmonary embolism is overdiagnosed on CTPA.4,5 We hypothesized that a limited negative CTPA result portends similar clinical outcomes to a definitively negative result; thus, emphasis on examination limitations may, in fact, be detrimental. Methods |This retrospective cohort studywasapprovedby the institutional review board of the Montefiore Medical Center, which waived written informed consent. Included were all adults with suspected pulmonary embolismwho underwent CTPA from July 1, 2011, through June 30, 2012, at the 3 emergency departments or inpatient sites of Montefiore Medical Center, Bronx,NewYork.Wedefined a limitednegativeCTPA result as one that reported no pulmonary embolism but also explicitly stated a limitation or qualification in the report impression. Theprimary outcomewas 90-day venous thromboembolism incidence, ameasureof the false-negative rate. Secondary outcomes were additional imaging, initiation of anticoagulation treatment, and bleeding complications.