3DFT MR angiography of carotid and basilar arteries

Three-dimensional Fourier transform (3DFT) time-of-flight and two-dimensional Fourier transform (2DFT) projection phase-contrast MR angiography was performed in eight healthy volunteers and in 14 patients with known carotid artery or basilar artery occlusion, stenosis, or dissection. Comparative angiography was available in 13 cases (although in some cases the studies were separated by a number of months) and duplex sonography in one case. After localization of the carotid artery bifurcations by using 2DFT projection phase-contrast angiography, multiple 1.25-mm contiguous images were obtained with the 3DFT technique. In all cases, the lesions were identified on MR angiography. Because flow is detected in a manner that is independent of flow-induced phase shifts in the 3DFT time-of-flight technique, signal loss arising from complex flow and turbulence is minimized, yet the flow image remains sensitive to all velocity components of flow. Applications of this technique are ideal for relatively straight vessels where flow is laminar, but it can also be used to evaluate the carotid artery bifurcations where flow becomes complex.