Figure 3. True stenotic defect. (a) A focal, dark filling defect is noted at the posterior bulb of the internal carotid artery (arrow) on two-dimensional Fourier transformation time-of-flight MR angiography (2D-FT TOF MRA). The defect appears as dark as the background darkness. The posterior wall contour is not preserved, and the margin of the defect is sharp. (b) The filling defect is well documented on digital subtraction angiography (arrow).