MRA as a Primary Screening Technique for Intra- and Extracranial Arterial Occlusive Diseases

We designed a protocol of 3-dimensional phase contrast (3D-PC-) magnetic resonance angiography (MRA), which was performed in the axial plane to assess the circle of Willis and in the coronal plane to assess the arteries of the head and neck, for screening of the intra- and extracranial arterial occlusive diseases. We evaluated the accuracy of 3D-PC-MRA comparing it with intraarterial angiography. In 52 consecutive patients presenting with clinical suspicion of a stroke, common carotid bifurcation (CCB), petrous segment of internal carotid artery (C5 segment), carotid siphon, middle cerebral artery (MCA), posterior cerebral artery (PCA), vertebral artery (VA), and basilar artery (BA) were evaluated. Both examinations were blindly graded as normal, mild (0-29% stenosis), moderate (30-69% stenosis), severe (70-99% stenosis), or occluded. In the two readers experienced and inexperienced in MR interpretation, Spearman rank correlations between the two techniques were 0.917/0.866 (CCB), 0.803/0.758 (C5 segment), 0.837/0.702 (carotid siphon), 0.841/0.787 (MCA), 0.899/0.886 (PCA), 0.935/0.889 (VA), and 0.932/0.900 (BA), respectively (p < 0.0001). 3D-PC-MRA and intraarterial angiography had a good overall agreement, suggesting its use as a primary screening technique for intra- and extracranial arterial occlusive diseases, although the diagnostic accuracy of MRA was relatively poor in the C5 segment, carotid siphon, and MCA presumably due to phase dispersion.