title: A randomized trial of spiral CT and ventilation perfusion scintigraphy for the diagnosis of pulmonary embolism.
abstract: OBJECTIVE
  To compare spiral computed tomographic pulmonary angiography (SCTA) with lung ventilation-perfusion scintigraphy (VQS) as the initial investigation of patients with suspected pulmonary embolism (PE).
  
  
  METHODS
  Prospective randomized trial of 78 patients with suspected pulmonary embolism. Patients underwent either SCTA or lung VQS as their initial investigation for PE. Cross-over between groups meant that 50 patients received both examinations. The clinicians' assessment of overall clinical likelihood of PE was also collected.
  
  
  RESULTS
  (1) It was possible to make a confident diagnosis in a significantly larger proportion of patients when SCTA was used as the initial investigation (35/39, 90%) compared with using VQS first (21/39, 54% P<0.001). The main difference between the two groups was that SCTA demonstrated lesions other than pulmonary embolism considered responsible for the patients' symptoms in 13/39 patients (33%) randomized to SCTA as the initial investigation and following a non-diagnostic VQS in 10/39 patients (25%) randomized to VQS as the initial investigation. (2) There was no difference in the prevalence or detection of PE in the two groups. SCTA demonstrated pulmonary emboli in 6/39 patients (16%) in the SCTA first group and VQS was high probability for PE in 5/39 patients (13%) in the VQS first group. SCTA detected PE in a further two patients in the VQS first group.
  
  
  CONCLUSIONS
  It is proposed that, where logistically feasible, SCTA should replace VQS as the initial investigation for PE in patients with an underlying cardio-respiratory disorder.
authors.affiliation: Department of Radiology, Addenbrooke's Hospital, and the University of Cambridge, UK.
authors.forename: J J
authors.initials: JJ
authors.lastname: Cross
authors.forename: P M
authors.initials: PM
authors.lastname: Kemp
authors.forename: C G
authors.initials: CG
authors.lastname: Walsh
authors.forename: C D
authors.initials: CD
authors.lastname: Flower
authors.forename: A K
authors.initials: AK
authors.lastname: Dixon
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014692:Ventilation-Perfusion Ratio