The goal of this project is to improve magnetic resonance angiography (MRA) to the point that it will be a viable alternative to intra-arterial X-ray angiography and provide new diagnostic information not available in other tests. A variety of MRA technqiue improvements have been developed and evaluated in order to consistently visualize arterial vessels on the order of 0.3 to 0.5 mm in diameter in a reasonable examination time. MRA using these improved techniques has been found adequate, by our neurovascular surgeons, to replace X-ray angiography in the pre-operative evaluation of unruptured intracranial aneurysms. It has also been accepted as the method of choice for aneurysm screening in high risk families. The acceptance of MRA for aneurysm screening and pre-surgical planning indicates that the tremendous improvements recently made in MRA have substantial clinical value, however, there is still a strong need for additional improvement. We believe that MRA can be made to consistently visualize aneurysm shape and morphology as well as provide better detail of the surrounding blood vessels. Improved MRA techniques may also enable better visualization of residual aneurysms in the vicinity of aneurysm clips. In the next funding period we will develop, refine, and evaluate 4 new pulse sequences and a set of new RF imaging coils with the goal to further improve vascular detail, increase spatial resolution and decrease clip artifacts. First, we will evaluate sliding interleaved projection reconstruction (SLIPR) and a novel improvement to sliding interleaved Ky (SLINKY). Both techniques show potential for improved vascular detail in non-contrast enhanced applications. We will also develop a novel hybrid dynamic/high-resolution contrast enhanced technique which should allow emphasis of arterial detail over venous detail. Reduction of clip artifacts will be addressed by using clips with the least amount of susceptibility and a combination of a new spectroscopic 3D TOF with high resolution black blood 3D fast spin echo. Finally, we will evaluate these MRA improvements in the following four specific clinical tasks related to aneurysm management: (1) Screening: The detection of aneurysms in high risk individuals, (2) followup studies on patients with untreated aneurysms, (3) pre-operative evaluation and planning, and (4) post-surgical followup in order to monitor procedure efficacy. Successful completion of this funding period will extend the domain in which high resolution MRA can provide significant diagnostic information essential for the detection and management of intracranial aneurysms. It will allow MRA to provide clinical information not currently obtained by other imaging modalities as well as replace some procedures currently performed by X-ray angiography.
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