title: CT Pulmonary Angiography: Using Decision Rules in the Emergency Department.
abstract: OBJECTIVE
  The aim of this study was to assess the appropriateness of utilization and diagnostic yields of CT pulmonary angiography (CTPA), comparing two commonly applied decision rules, the pulmonary embolism (PE) rule-out criteria (PERC) and the modified Wells criteria (mWells), in the emergency department (ED) setting.
  
  
  METHODS
  Institutional review board approval was obtained for this HIPAA-compliant, prospective-cohort, academic single-center study. Six hundred two consecutive adult ED patients undergoing CTPA for suspected PE formed the study population. The outcome was positive or negative for PE by CTPA and at 6-month follow-up. PERC and mWells scores were calculated. A positive PERC score was defined as meeting one or more criteria and a positive mWells score as >4. The percentage of CT pulmonary angiographic examinations that could have been avoided and the diagnostic yield of CTPA using PERC, mWells, and PERC applied to a negative mWells score were calculated.
  
  
  RESULTS
  The diagnostic yield of CTPA was 10% (61 of 602). By applying PERC, mWells, and PERC to negative mWells score, 17.6% (106 of 602), 45% (273 of 602), and 17.1% (103 of 602) of CT pulmonary angiographic examinations, respectively, could have been avoided. The diagnostic yield in PERC-positive patients was higher than in mWells-positive patients (10% [59 of 602] vs 8% [49 of 602], P < .0001). Among PERC-negative and mWells-negative patients, the diagnostic yields for PE were 1.9% (2 of 106) and 4% (12 of 273), respectively (P = .004). The diagnostic yield of a negative PERC score applied to a negative mWells score was 1.9% (2 of 103).
  
  
  CONCLUSIONS
  The use of PERC in the ED has the potential to significantly reduce the utilization of CTPA and misses fewer cases of PE compared with mWells, and it is therefore a more efficient decision tool.
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan. Electronic address: jstoanov@umich.edu.
authors.forename: Jadranka
authors.initials: J
authors.lastname: Stojanovska
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Ruth C
authors.initials: RC
authors.lastname: Carlos
authors.affiliation: Emergency Medicine, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Keith E
authors.initials: KE
authors.lastname: Kocher
authors.affiliation: University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Arun
authors.initials: A
authors.lastname: Nagaraju
authors.affiliation: University of Michigan Medical School, Ann Arbor, Michigan.
authors.forename: Karen
authors.initials: K
authors.lastname: Guy
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Aine M
authors.initials: AM
authors.lastname: Kelly
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Aamer R
authors.initials: AR
authors.lastname: Chughtai
authors.affiliation: Department of Radiology, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Ella A
authors.initials: EA
authors.lastname: Kazerooni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000706:statistics & numerical data*; D003422:Critical Care / Q000706:statistics & numerical data; D020000:Decision Support Systems, Clinical / Q000706:statistics & numerical data*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006801:Humans; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D015995:Prevalence; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D019564:Unnecessary Procedures / Q000706:statistics & numerical data*; D014600:Utilization Review; D055815:Young Adult
keywords: Pulmonary embolism rule-out criteria; computed tomographic pulmonary angiography; emergency department; modified Wells score; pulmonary embolism