Four-vessel biplanar cerebral arteriography (ART) has been considered the gold standard for diagnosis of BCVI. Unfortunately, it is invasive and resource intensive, and its risks include complications related to catheter insertion (1–2% hematoma; arterial pseudoaneurysm), contrast administration (1–2% renal dysfunction; allergic reaction), and stroke (<1%).¹¹ Duplex ultrasonography is widely used for imaging the extracranial carotid arteries. However, because of its technical limitations and poor sensitivity in clinical trials, there is virtually no role for ultrasonography for BCVI screening.^3,27 Similarly, with its documented poor sensitivity and specificity for BCVI,^12,28 magnetic resonance angiography is not considered a standard screening test for BCVI. In contrast, CT angiography (CTA) has emerged as the preferred screening test for BCVI. Although the accuracy of early generation CTA was poor,^12,28 it was improved with multidetector-row (4- and 8-slice) CTA.^29,30 Sixteen-slice CTA has been adopted by a number of centers and seems to reliably identify clinically significant BCVI.^15,26 Three published studies have evaluated the accuracy of 16-slice CTA compared with ART. Eastman et al.¹⁴ reported 100% sensitivity of 16-slice CTA for carotid and 96% sensitivity for vertebral artery injuries. Utter et al.29 performed ART on a subset (30%) of their patients with normal CTA and initially found that CTA missed seven BCVI among 82 patients, for a negative predictive value of 92%. However, retrospective review of the CTA images found that the injuries were evident in six of the seven patients, and that the seventh patient’s abnormality was most likely not traumatic in origin. Malhotra et al.³¹ have offered a note of caution, reporting 43% false-positive and 9% false-negative rates for CTA. However, as in the series of Utter et al.,²⁹ the inaccuracy of CTA seemed to be related in large part to the radiologists’ inexperience, as all of the missed BCVI occurred in the first half of the study period. Thus, it seems that 16-slice (or more) CTA is reliable for screening for clinically significant BCVI, but that the accuracy diminishes with fewer detector rows. If CTA is not available, ART is the gold standard. If ART is not available, it is recommended that an institutional clinical practice guideline be outlined that considers transfer to a trauma center for patients at high risk. In the setting of a symptomatic patient and normal noninvasive screening study, ART is recommended to definitively exclude injury.