Background: In light of their potential for devastating consequences, a liberalized screening approach for blunt cerebrovascular injuries (BCVI) is becoming increasingly accepted. The "gold standard" for diagnosis of BCVI is arteriography; however, noninvasive diagnostic alternatives offer clear advantages. Recent series have demonstrated the ability of computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) to identify BCVI, but have not compared their accuracy with arteriography. We hypothesized that CTA or MRA could reliably identify BCVI, obviating the need for arteriography. The purpose of this study was to determine the accuracy of CTA and MRA in identifying BCVI in asymptomatic patients.
Methods: Asymptomatic patients meeting criteria for BCVI screening underwent arteriography, according to our institutional standard. A subset of patients requiring computed tomographic scanning underwent CTA; a subset of patients requiring magnetic resonance imaging underwent MRA. All of the studies were interpreted by radiologists in a blinded manner. Data were analyzed for sensitivity and specificity.
Results: Forty-six patients underwent both CTA and arteriography. Of 23 with a normal CTA examination, 7 (30%) had BCVI on arteriography. Of 23 with an abnormal CTA examination, 8 (35%) had a normal arteriogram. The sensitivity, specificity, positive predictive value, and negative predictive value of CTA were 68%, 67%, 65%, and 70%, respectively. CTA missed 55% of grade I injuries, 14% of grade II injuries, and 13% of grade III injuries. Sixteen patients underwent both MRA and arteriography. One (11%) had a false-negative MRA result, and four (57%) had false-positive MRA results (75% sensitivity, 67% specificity, 43% positive predictive value, 89% negative predictive value).
Conclusion: CTA and MRA can identify BCVI, but they miss grade I, II, and III injuries. Future technical modifications may improve their accuracy. A prospective multicenter trial is warranted to define the capabilities and limitations of these noninvasive modalities. In the interim, arteriography remains the gold standard for diagnosis, but if arteriography is not available, CTA or MRA should be used to screen for BCVI in patients at risk.