title: Perfusion and ventilation scans in patients with extensive obstructive airway disease: utility of single-breath (washin) xenon-133.
abstract: The presence of extensive obstructive airway disease in many patients leads to an interpretation of intermediate or indeterminate probability for pulmonary emboli using ventilation/perfusion lung scans. We observed that patients with extensive obstructive airway disease having perfusion abnormalities matching those on a single-breath xenon image usually have a normal pulmonary angiogram. This study's objective was to further assess the utility of a single-breath image in evaluating patients with extensive obstructive airway disease and abnormal perfusion studies categorized as having intermediate or indeterminate probability of pulmonary embolism in an attempt to decrease the number of nondiagnostic studies.
  
  
  METHODS
  We studied retrospectively 33 patients with extensive obstructive airway disease, with abnormal perfusion scans and no infiltrates on chest x-ray categorized as having intermediate or indeterminate probability of pulmonary embolism. We established the presence or absence of matching ventilation and perfusion abnormalities by comparing perfusion scan and single-breath images.
  
  
  RESULTS
  Among 25 patients with perfusion abnormalities matching the initial ventilation pattern on single-breath images, only 1 (4%) had pulmonary emboli as documented by pulmonary angiogram. Four out of the remaining 8 patients with no matching perfusion and single-breath ventilation pattern had pulmonary emboli (50%).
  
  
  CONCLUSIONS
  Patients categorized by ventilation/perfusion scintigraphy as having intermediate or indeterminate probability for pulmonary emboli due to the presence of extensive obstructive airway disease can be further subclassified using single-breath images. Patients with matching perfusion and single-breath ventilation pattern should be categorized as having low probability for pulmonary embolism, regardless of the extent of the ventilation abnormalities.
authors.affiliation: Department of Radiology, Eugene L. Saenger Radioisotope Laboratory, University of Cincinnati Hospital, Ohio 45267-0577.
authors.forename: A H
authors.initials: AH
authors.lastname: Elgazzar
authors.forename: E B
authors.initials: EB
authors.lastname: Silberstein
authors.forename: J
authors.initials: J
authors.lastname: Hughes
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008173:Lung Diseases, Obstructive / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000209:etiology; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D012307:Risk Factors; D014980:Xenon Radioisotopes / Q000008:administration & dosage
chemical_list: D014980:Xenon Radioisotopes