Ventilation-perfusion scanning and helical CT in suspected pulmonary embolism: meta-analysis of diagnostic performance.

PURPOSE To perform meta-analysis of literature about the role of helical computed tomography (CT) and ventilation-perfusion (V-P) scanning in detection of acute pulmonary embolism (PE) by using summary receiver operating characteristic (ROC) curve analysis. MATERIALS AND METHODS V-P scanning articles published from January 1985 to March 2003 and helical CT articles published from January 1990 to March 2003 in MEDLINE and EMBASE databases were included if (a) tests were performed for evaluation of acute PE, (b) conventional angiography was the reference standard, and (c) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available. Sensitivity analysis was conducted by excluding articles published before 1995. RESULTS A total of 12 articles discussing helical CT and/or V-P scanning were included. With a random-effects model, pooled sensitivity for helical CT was 86.0% (95% confidence interval [CI]: 80.2%, 92.1%), and specificity was 93.7% (95% CI: 91.1%, 96.3%). V-P scanning yielded low sensitivity of 39.0% (95% CI: 37.3%, 40.8%) but high specificity of 97.1% (95% CI: 96.0%, 98.3%) with high probability threshold. V-P scanning yielded high sensitivity of 98.3% (95% CI: 97.2%, 99.5%) and low specificity of 4.8% (95% CI: 4.7%, 4.9%) with normal threshold. Regression coefficients for helical CT angiography were 0.588 (95% CI: -1.55, 2.74) and 4.14 (95% CI: -0.002, 8.28) versus V-P scanning with high and normal thresholds, respectively. Regression coefficients for helical CT angiography were 0.588 (95% CI: -1.55, 2.74) and 4.14 (95% CI: -0.002, 8.28) versus V-P scanning with high and normal thresholds, respectively. CONCLUSION Helical CT has greater discriminatory power than V-P scanning with normal and/or near-normal threshold to exclude PE, while helical CT and V-P scanning with high probability threshold had similar discriminatory power in the diagnosis of PE.