Comparison of transcranial Doppler sonography with and without imaging in the evaluation of children with sickle cell anemia.

OBJECTIVE: High blood flow velocity in the middle cerebral artery or distal internal carotid artery, as measured by nonduplex transcranial Doppler sonography, predicts stroke in children with sickle cell anemia. However, velocities measured using the more widely available duplex transcranial Doppler imaging equipment may not be comparable. We sought to determine the magnitude and significance of the potential differences. SUBJECTS AND METHODS: We performed 55 paired examinations with duplex imaging and nonduplex nonimaging sonography machines on 53 children with sickle cell anemia. Examinations were performed consecutively by three sonographers blinded to the results of the opposing study. Velocities were measured in five clinically relevant vessels.
RESULTS: Time-averaged mean maximum (TAMx) velocity measurements obtained with the duplex equipment were significantly lower than those made with the nonduplex equipment for all vessels except the posterior cerebral artery. The mean differences were 10.9% (p < 0.0001) in the middle cerebral artery, 12.7% (p = 0.002) in the anterior cerebral artery, 2.2% (p = 0.69) in the posterior cerebral artery, 21.0% (p < 0.0001) in the distal internal carotid artery, and 15.3% (p < 0.0001) at the bifurcation of the distal internal carotid artery.
CONCLUSION: If TAMx velocities measured with duplex equipment are used to assign stroke risk in children with sickle cell anemia, we suggest that 180 cm/sec or more should be considered abnormal, and 153-179 cm/sec, as conditional. These values are 10% lower than those obtained from the nonduplex equipment used in the Stroke Prevention Trial in Sickle Cell Anemia study.