|Computed Tomograhic Angiography For the Diagnosis of Blunt Carotid/Vertebral Artery Injury: A Note of Caution|
|Ajai K Malhotra*, Marc Camacho*, Rao R Ivatury, Michel B Aboutanos*, Therese M Duane*, Charlotte Cockrell*, Christopher T Borchers*, Nancy Martin* |
Medical College of Virginia, Virginia Commonwealth University, Richmond, VA
|OBJECTIVE(S): Computed tomographic angiography (CTA) by 16-channel multi-slice scanner is increasingly replacing conventional angiography (CA) for diagnosing or excluding blunt carotid/vertebral artery injuries (BCVI). To date there has been only one study in which all patients received both examinations. That study (AAST'05: JOT’06;60:925-29) reported high accuracy for CTA. The current prospective parallel comparative study questions this high accuracy.|
METHODS: Patients at risk of BCVI (facial/cervical-spinal fractures; unexplained neurologic deficit; anisocoria; clinical suspicion) underwent both CTA (16-channel multi-slice scanner) and CA. Results of the two studies and the clinical course, were prospectively recorded.
RESULTS: 76 consecutive patients met inclusion criteria. 20/76 (26%) CAs identified 23 BCVIs (Carotid-13, Vertebral-10). Among these 20 CTAs, 15 identified 17 BCVIs (Carotid-9, Vertebral-8) (true positives), and 5 failed to identify 6 BCVIs (Carotid-4, Vertebral-2) (false negatives). 56/76 CAs were normal. Of these 56 CTAs, 6 were falsely suspicious for 10 BCVIs (Carotid-3, Vertebral-7) (false positives), and 47 were normal (true negatives). The remaining 3 CTAs were non-evaluable (mistimed contrast-1, streak artifact-2). 12/73 (16%) evaluable CTAs, were suboptimal (mistimed contrast-2; streak artifacts-10). Excluding the 3 non-evaluable CTAs, the sensitivity, specificity, positive and negative predictive values of CTA for diagnosing or excluding BCVI were, 75%, 89%, 71% and 90% respectively. No neurologic events attributable to missed BCVI were recorded.
CONCLUSIONS: Current CTA technology cannot reliably diagnose or exclude BCVI. 20% of CTAs are either non-evaluable or suboptimal. The current trend towards utilizing CTA to screen for and/or diagnose these rare but potentially devastating injuries is dangerous.
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