MR angiography of basilar artery thrombosis

The goal of this investigation is to identify basilar artery thrombosis using MR phase-contrast angiography. Four patients presenting with brain-stem dysfunction were evaluated with standard MR imaging techniques and MR angiography. Sagittal T1-weighted images, axial spin-density, axial T2-weighted images, and (in two patients) contrast-enhanced T1-weighted images were obtained. The standard imaging sequences were followed by MR angiography. The MR angiograms were obtained with two-dimensional (2D) multisection and 3D pulse sequences modified to implement bipolar gradient phase-contrast angiography. Asymmetric echo acquisition was employed to reduce the TE to approximately 14 msec. Velocity-compensated field of view selection and readout gradients were used. Weak dephasing gradients in the projection direction suppressed static spin signal. The total image acquisition times were typically 4 minutes (2D) and 14 minutes (3D). Images for the other three orthogonal velocity components were added in quadrature. In all four patients, basilar artery thrombosis or severe compromise of the basilar artery was clearly documented with MR angiography. Intraluminal thrombus was also identified on the standard imaging sequences. Standard angiography was also performed in three patients, validating the MR observations. MR angiography is a useful adjunct to the standard MR imaging sequences for the diagnosis of basilar artery occlusion