title: The prevalence of symptomatic and coincidental pulmonary embolism on computed tomography.
abstract: OBJECTIVE
  To investigate the proportion of pulmonary embolism (PE) on computed tomographic pulmonary angiography (CTPA) and the proportion of coincidental PE on regular contrast-enhanced CT in oncological and nononcological patients.
  
  
  METHODS
  This study received internal review board approval and was Health Insurance Portability and Accountability Act compliant. All consecutive adult patients who had contrast-enhanced chest CT or dedicated CTPA during January 2005 were studied. Procedural codes were used to identify cases, and all CT images were reviewed. Clinical data collected included oncology status, chemotherapy regimen, site of tumor, and location of PE. chi2 Tests were used for statistical analysis.
  
  
  RESULTS
  Two hundred twenty-nine patients had CTPA, and 27 (11.8%) of them were positive for PE. Of 1168 patients who had contrast-enhanced CT for other indications, coincidental PE was found in 21 patients (1.8%). The proportions of coincidental PE were 3.3% of patients with progressive cancer, 2.5% of patients with stable cancer, 0.7% of patients with no evidence of cancer posttreatment, and 1.0% of nononcological patients. Coincidental PE was found more frequently in patients with progressive cancer compared with nononcological patients (P = 0.035). Patients who were on chemotherapy also had a higher risk of coincidental PE (P=0.019).
  
  
  CONCLUSIONS
  The prevalence of symptomatic PE on dedicated CTPA was 11.8%, and the rate of coincidental PE on contrast-enhanced CT was 1.8%. Coincidental PE was significantly higher inpatients with progressive cancer or those receiving chemotherapy.
authors.affiliation: Harvard School of Public Health, Massachusetts General Hospital, Boston, MA 02114-2696, USA. gladwin.hui@utoronto.ca
authors.forename: Gladwin C
authors.initials: GC
authors.lastname: Hui
authors.forename: Alan
authors.initials: A
authors.lastname: Legasto
authors.forename: Conrad
authors.initials: C
authors.lastname: Wittram
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed