Sixteen-slice CT angiography in patients with suspected blunt carotid and vertebral artery injuries

BACKGROUND: We sought to determine whether 16-slice multidetector CT angiography (CTA) has sufficient negative predictive value for use as the initial imaging examination for patients with suspected blunt carotid and vertebral artery injury (BCVI) and to estimate the positive predictive value of different screening criteria in assessing BCVI. STUDY DESIGN: We conducted a retrospective study of patients who were imaged for suspected BCVI at a Level I trauma center during 2004. The policy at our center was to evaluate all patients with specific indications with CTA, and at the discretion of the clinical service, four-vessel digital subtraction angiography (DSA) if the CTA was normal. We recorded injury grade, location, and diagnostic certainty from the imaging report. The primary outcome was the proportion of patients with normal CTA who also had normal DSA. RESULTS: Of 372 patients imaged with CTA for suspected BCVI, 271 had normal studies. Eighty-two (30%) of those with normal initial CTA were further examined with DSA, which was normal or equivocal in 75 of these 82 patients (CTA negative predictive value, 92% [95% CI, 83% to 97%]). The aggregate positive predictive value of BCVI screening criteria was 19% (95% CI, 14% to 23%). Lateral element cervical vertebral fractures and-skull base fractures were the most predictive criteria. CONCLUSIONS: Multidetector CTA misses relatively few injuries and adequately supplants DSA as a screening study in patients with risk factors for BCVI Radiologists should maintain a high degree of suspicion in patients who meet screening criteria. Optimal imaging strategies should focus on the most predictive criteria.