Figure 11

Severe Stenosis Misclassification. A. Misalignment of the Doppler cursor, yielding an elevated angle measurement, results in an EDV > 1.4 m/s, indicating a severe stenosis within this stent. Proper cursor alignment would result in EDV = 1.02 m/s, indicating a moderate stenosis. Note the aliased systolic peak extending to the 100 cm/s value. After correcting for aliasing and for angle misalignment, the correct systolic velocity is 3.8 m/s. B. Faced with a bidirectional waveform, the examining sonographer measured the reversed (+) portion of the waveform (indicating arterial flow from brain to heart), measuring the EDV as 1.09 m/s and indicating moderate stenosis, rather than the correct 1.55 m/s value indicating severe stenosis. They also measured a PSV of 4.58 m/s rather than the correct 4.25 m/s value.