Acute Care/Hospitalization

Hyperdense basilar artery on unenhanced CT scan predicts a clot in the artery and poorer outcome among stroke patients

Blockage of the basilar artery, which is located along the brainstem in the back of the brain, is typically a devastating event that can lead to major stroke-related disability and death. Early diagnosis is critical so that clot-busting therapy or other supportive measures can begin. However, most community medical centers do not routinely perform advanced imaging such as enhanced computerized tomography angiography (CTA) or magnetic resonance angiography. They rely instead on unenhanced computerized tomography (CT) for their clinical decisions. A new study suggests that community hospitals can use unenhanced CT to diagnose these dangerous blood clots. It found that a hyperdense basilar artery (HDBA) sign on unenhanced CT was a strong predictor of a blood clot in the basilar artery, as well as short- and long-term patient outcome.

The researchers examined unenhanced CT scans obtained within 24 hours of symptom onset in 95 patients with suspected posterior circulation stroke. Three neuroimagers blinded to clinical outcomes and results of the concurrent CT angiography (used as the reference standard) rated the presence of HDBA sign on unenhanced CT scans on a 5-point scale for level of certainty (1 for definitely absent to 5 for definitely present). Using a certainty cutoff score of 4 or more (probable, definite), HDBA sign had 71 percent sensitivity, 98 percent specificity, 94 percent accuracy, 83 percent positive predictive value, and 95 percent negative predictive value for basilar artery occlusion.

The HDBA sign increased fivefold the likelihood of poor long-term outcome. The only independent predictors of discharge stroke score were admission National Institute of Health Stroke Scale (NIHHS) and HDBA sign. Significant independent predictors of poor long-term outcome were patient age, admission NIHSS, history of stroke/transient ischemic attack (mini stroke), and HDBA sign.

The study was supported by the Agency for Healthcare Research and Quality (HS11392). More details are in "Hyperdense basilar artery sign on unenhanced CT predicts thrombus and outcome in acute posterior circulation stroke," by Gregory V. Goldmakher, M.D., Ph.D., Erica C.S. Camargo, M.D., M.M.Sc., Ph.D., Karen L. Furie, M.D., M.P.H., and others, in the January 2009 Stroke 40, pp. 134-139.

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