709

Introduction: Blunt trauma to the carotid and/or vertebral arteries, collectively termed blunt cerebrovascular injury (BCVI), occurs in approximately 1% of hospitalized blunt trauma victims. Although computed tomographic angiography (CTA) is the most frequently used BCVI imaging test, controversy exists as to whether its diagnostic performance compares favorably with the reference-standard, digital subtraction angiography (DSA). Hypothesis: The diagnostic accuracy of CTA compares unfavorably with DSA for BCVI detection in trauma patients. Methods: We searched electronic databases (MEDLINE, PubMed, EMBASE, Cochrane, and Web of Science) (1950 to May 22nd, 2012), article bibliographies, conference proceedings (2008 to 2011), and clinical trials registries. Two investigators independently screened articles and selected studies comparing the accuracy of CTA with DSA for BCVI detection in trauma patients. Pooled estimates of sensitivity, specificity, and positive and negative likelihood ratios were calculated using bivariate random effects models. Results: Eight studies that examined 5704 carotid or vertebral arteries in 1426 trauma patients met inclusion criteria. The pooled sensitivity and specificity for BCVI detection with CTA versus DSA was 66% (95% CI, 49% to 79%; I2=80.4%) and 97% (95% CI, 91% to 99%; I2=94.6%), respectively. Corresponding pooled positive and negative likelihood ratios were 20.0 (95% CI, 6.9 to 58.4; I2=87.7%) and 0.35 (95% CI, 0.22 to 0.56; I2=74.9%), respectively. Although the pooled sensitivity varied with the number of available CT slices, the training of interpreting radiologists, and in a pattern suggestive of differences in diagnostic threshold for judging CTA positivity, it remained =80% among studies that used scanners with =16-slices per rotation and where the CTA was read by neuroradiologists. Conclusions: Existing evidence suggests that the diagnostic performance of CTA varies considerably across studies, likely due to an implicit variation in diagnostic threshold across trauma centers. Moreover, although CTA appears to lack sensitivity to adequately rule-out BCVI, it may be useful to rule-in BCVI among trauma patients with a high pretest probability of injury.