title: Combined helical computed tomographic pulmonary angiography and lung perfusion scintigraphy for investigating acute pulmonary embolism.
abstract: OBJECTIVE
  To evaluate a diagnostic protocol incorporating helical computed tomographic pulmonary angiography (CTPA) and lung perfusion scintigraphy in the detection or exclusion of pulmonary embolism (PE) in routine clinical practice.
  
  
  METHODS
  A prospective observational study of 808 consecutive patients with suspected acute PE was undertaken over a 23-month period. Twenty-nine cases who failed to follow the protocol were excluded, leaving 779 cases to be reviewed. The three main outcome measures were negative perfusion scintigraphy, positive CTPA and other significant abnormalities demonstrated on CT.
  
  
  RESULTS
  Two hundred and thirty-one (30%) had negative perfusion scintigraphy and no further investigation. CTPA was performed in 548 (70%) and PE confirmed in 193 (25% of all patients). Other significant abnormalities were demonstrated in 25 (3%). CTPA was technically inadequate in 15 (2%).
  
  
  CONCLUSIONS
  A confident conclusion was achieved in 449 cases (58%), with PE excluded in 231 (30%), proved in 193 (25%), and relevant alternative abnormalities found in 25 (3%). This protocol using both perfusion scintigraphy and CTPA is practical and more effective than either investigation alone.
authors.affiliation: Department of Chest Medicine, Stoke Mandeville Hospital, Aylesbury, Buckinghamshire, UK.
authors.forename: Helen T H
authors.initials: HT
authors.lastname: Wilson
authors.forename: Tom M M
authors.initials: TM
authors.lastname: Meagher
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Williams
mesh_terms: D000208:Acute Disease; D000465:Algorithms; D006801:Humans; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*