Review: helical CT has better discriminatory power than ventilation-perfusion scan to exclude pulmonary embolism.

M e t h o d s Data sources: MEDLINE (1985 to 2003), EMBASE/Excerpta Medica (1985 to 2003), bibliographies of relevant studies, and contact with experts. Articles on helical CT were limited to those published between 1990 and 2003, and articles on V/Q scan were limited to those published between 1985 and 2003. Study selection and assessment: Englishlanguage studies that used helical CT or V/Q scan as a diagnostic test for acute PE and pulmonary angiography as the diagnostic standard; reported true-positive, false-positive, true-negative, and false-negative data in absolute numbers; and had a time interval ≤ 48 hours between the test and the diagnostic standard. Studies were assessed for design, blinding between readers, verification bias, and interpretation bias. Outcomes: Diagnostic test characteristics and regression coefficients from summary receiver-operating characteristic (ROC) curve analysis. M a i n r e s u l t s 12 studies were included. 9 studies (n = 520, mean age range 34 to 63 y based on 8 studies) used helical CT, 5 studies (n = 1269, mean age range 53 to 63 y based on 3 studies) used V/Q scan, and 2 studies used both helical CT and V/Q scan. Test characteristics for helical CT and V/Q scan are in the Table. Summary ROC curve analysis showed that helical CT had greater discriminatory power than V/Q scan when an “intermediate-” or a “high-” probability V/Q scan result was considered positive for PE (regression coefficient 4.14, P = 0.05) but had similar discriminatory power when only a “high-probability” V/Q scan result was considered positive for PE (regression coefficient 0.59, P = 0.46).