title: Use of computed tomography pulmonary angiography in the diagnosis of pulmonary embolismin patients with an intermediate probability ventilation/perfusion scan.
abstract: BACKGROUND
  Computed tomography pulmonary -angiography (CTPA) plays an increasingly important role in the diagnosis of pulmonary embolism (PE). Although accurate in the detection of large PE, its accuracy in other patient groups is yet to be defined.
  
  
  OBJECTIVE
  To compare CTPA with pulmonary angiography as a second-line investigation in patients with a ventilation/perfusion (VQ) scan indicating an intermediate probability of PE.
  
  
  METHODS
  We recruited 25 patients over a 17-month period. Subjects were eligible if they: (i). had clinically suspected PE, (ii). had a VQ scan indicating an intermediate probability of PE and (iii). were referred for pulmonary angiography. Subjects underwent CTPA within 36 h of the VQ scan. CTPA was interpreted without knowledge of the results of the pulmonary angiogram by two of the authors.
  
  
  RESULTS
  PE was prevalent (i.e. embolus detected at pulmonary angiography) in seven of 25 subjects (28%). The sensitivity of CTPA was 57% and the specificity was 94%.
  
  
  CONCLUSIONS
  In the setting of intermediate-probability VQ scanning, CTPA may be used to clarify the diagnosis of PE. However, a negative CTPA cannot -definitely exclude PE. Conventional pulmonary angiography may be necessary to determine the presence of PE if CTPA is negative.
authors.affiliation: Department of Respiratory Medicine, Royal North Shore Hospital, University of Sydney, New South Wales, Australia. estone@med.usyd.edu.au
authors.forename: E
authors.initials: E
authors.lastname: Stone
authors.forename: P
authors.initials: P
authors.lastname: Roach
authors.forename: E
authors.initials: E
authors.lastname: Bernard
authors.forename: G
authors.initials: G
authors.lastname: Briggs
authors.forename: A
authors.initials: A
authors.lastname: Havryk
authors.forename: K
authors.initials: K
authors.lastname: Faulder
authors.forename: C
authors.initials: C
authors.lastname: Dennis
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011652:Pulmonary Circulation; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013668:Technetium Tc 99m Aggregated Albumin; D036542:Tomography, Spiral Computed; D014692:Ventilation-Perfusion Ratio
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin