Contrast-enhanced MR angiography of the intracranial circulation.

NCE MRA can provide the authors with useful diagnostic information in patients suffering from intracranial vascular disease, often leading to improved or altered treatment decisions. Most centers have used 3D TOF for evaluation of stroke-the most common cerebral vascular disease. Because of slow and disturbed flow, conventional 3D TOF MRA tends to overestimate stenotic lesions and occluded arteries and this can confound neurovascular assessment in stroke patients. Post contrast 3D TOF techniques provide a more robust and more specific method for imaging the intracranial circulation that overcomes the drawbacks of conventional 3D TOF. In the setting of acute ischemic stroke, the authors have found that the combination of conventional and CE 3D TOF MRA improves their overall diagnostic ability. Dynamic and time-resolved CE MRA techniques have evolved rapidly. Time-resolved CE MRA, in particular, is emerging as a useful technique for imaging dynamic vascular pathologies such as AVMs. Unfortunately, time-resolved MRA of the intracranial circulation provides images with low spatial resolution and is currently limited to subsecond frame rate 2D acquisitions, and less than 2 seconds frame rates for 3D acquisitions. Nevertheless, like in other vascular regions, CE MRA represents a milestone for non-invasive intracranial vascular imaging. The continuing development of CE MRA techniques and of new contrast agents will lessen the need for intra-arterial angiography in the future.