title: MDCT diagnosis of acute pulmonary embolism in the emergent setting.
abstract: To compare utilization of CT pulmonary angiogram (CTA) for diagnosis of pulmonary embolism (PE) in an emergency department (ED) with unstructured CT ordering to published rates of CT positivity in other EDs including those employing decision support and to identify pathways for improved utilization via collaboration with our pathology and ED colleagues. Two hundred seventeen patients over a 2.5-month time period who received a CTA for PE were reviewed with exclusion of pediatric patients and all sub-optimal, non-diagnostic, or equivocal scans; 21 were excluded leaving a sample of 196 patients. The rate of PE diagnosis and association of PE positivity with selected factors (D-dimer testing) was assessed. The percentage of cases positive for PE was 10.7 % (21/196) which is similar to the frequently published rate of 10 % in other emergency departments including settings that have studied the use of decision support. D-dimer testing was performed in 40.3 % of cases. In 29.6 % (58/196) of subjects, D-dimer was positive, 10.7 % (21/196) was negative, and 59.7 % (117/196) was not assessed. Prevalence of PE among D-dimer negative (0 %, 0/21) was lower versus positive D-dimer (12.1 %, 7/58) and unknown D-dimer patients (12.0 %, 14/117). D-dimer had 100 % (21/21) negative predictive value for the diagnosis of PE. While this suggests that D-dimer is useful to rule-out PE, due to the small number of patients with PE, the 95 % confidence intervals are wide and the post-test likelihood of PE could be as high as 14 %. The rate of CT positivity for PE in an ED with unstructured CT ordering is similar to that in other published series including as series in which decision support was used. While D-dimer had high negative predictive value, large studies are needed to confirm this high sensitivity and potentially increase its use in ruling out PE without CT and to reduce CT ordering particularly in patients with sufficiently low clinical pre-test probability of PE.
authors.affiliation: Department of Radiology, NYU Langone Medical Center, 660 1st Avenue, 3rd Floor, New York, NY, 10016, USA, Nainesh.Parikh@nyumc.org.
authors.forename: Nainesh
authors.initials: N
authors.lastname: Parikh
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Morris
authors.forename: James
authors.initials: J
authors.lastname: Babb
authors.forename: Maj
authors.initials: M
authors.lastname: Wickstrom
authors.forename: John
authors.initials: J
authors.lastname: McMenamy
authors.forename: Rahul
authors.initials: R
authors.lastname: Sharma
authors.forename: David
authors.initials: D
authors.lastname: Schwartz
authors.forename: Mark
authors.initials: M
authors.lastname: Lifshitz
authors.forename: Danny
authors.initials: D
authors.lastname: Kim
mesh_terms: D000208:Acute Disease; D000328:Adult; D000792:Angiography; D015415:Biomarkers / Q000032:analysis; D003661:Decision Support Techniques; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D006801:Humans; D008297:Male; D061330:Multidetector Computed Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D