Abstract
Objective. The authors evaluate blood flow velocities in the medial cerebral artery (MCA) and the basilar artery using magnetic resonance (MR) phase contrast technique in comparison with transcranial Doppler ultrasound (TCD). Eleven healthy male volunteers were studied. TCD of the MCA (n = 22) and basilar artery (n = 11)was performed. MR phase velocity mapping was done in each vessel at the same ...
Abstract
Objective. The authors evaluate blood flow velocities in the medial cerebral artery (MCA) and the basilar artery using magnetic resonance (MR) phase contrast technique in comparison with transcranial Doppler ultrasound (TCD). Eleven healthy male volunteers were studied. TCD of the MCA (n = 22) and basilar artery (n = 11)was performed. MR phase velocity mapping was done in each vessel at the same location where the TCD signal had been acquired. A 2-dimensional FLASH sequence with retrospective cardiac gating and an average temporal resolution of 45 ms was used. Resistance indices (Rls) and pulsatility indices (Pls) were calculated for both modalities. The TCD insonation angle was measured retrospectively with MR, and TCD velocities were corrected based on these measurements. The comparison of flow velocities obtained with TCD and MR led to a low correlation coefficient with regard to the basilar artery and the MCA: maximum systolic velocity, r = 0.02 and r = 0.50, respectively; enddiastolic velocity, r = 0.47 and r = 0.65, respectively; mean velocity, r = 0.52 and r = 0.66, respectively. The average Pls in the basilar artery and the MCA were 0.80 and 0.81 with MR and 0.65 and 0.85 with TCD, respectively. The average Rls in the basilar artery and the MCA were 0.52 and 0.54 with MR and 0.52 and 0.55 with TCD, respectively. The TCD insonation angle differed significantly from the ideal value in the basliar artery (mean value = 32.6 degrees) and the MCA (mean value = 26.5 degrees). The authors find a low correlation between velocities measured with MRI and TCD but similar results with regard to the Pls and Rls. Several sources of error, such as a nonideal TCD insonation angle, were identified.
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