Optimal values of flow velocity on transcranial Doppler in grading middle cerebral artery stenosis in comparison with magnetic resonance angiography

Background and purpose. To investigate the optimal values of flow velocity on transcranial Doppler (TCD) in grading the severity of middle cerebral artery (MCA) stenosis in comparison with magnetic resonance angiography (MRA). Methods. Both TCD and MRA examinations were performed on 148 asymptomatic patients. The peak flow velocities of each MCA were recorded. Severity of MCA stenosis on MRA was classified as normal-mild (< 50% lumen diameter reduction), moderate (50%-75%), and severe-void (> 75% and void of flow signal). Results. Among 296 MCAs evaluated, normal-mild stenosis was found in 75 (25%), moderate stenosis in 112 (38%), and severe stenosis in 109 (37%). The mean of systolic velocity (Vs) of MCA differed significantly among these three groups: mean Vs = 121.83 +/- 22.52 cm/s in the normal-mild group; 155.96 +/- 21.62 cm/s for the moderate group; and 199.39 +/- 43.86 cm/s for the severe group (P <.001). The optimal cutoff velocity for detection of MCA (> 50%) stenosis was found at Vs > 140 cm/s on TCD (area under the ROC curve is 0.87, P < 0.001). The best cutoff points for grading severity of on TCD were 140 cm/s and 180 cm/s. Conclusion. TCD enables grading of the severity of MCA stenosis according to the flow velocity, This method provides a noninvasive and reliable method for grading MCA stenosis and allows longitudinal monitoring of the relationship between clinical outcome and hemodynamic change.