Hybrid HYPR MRA

¹Medical Physics, University of Wisconsin, Madison, Madison, WI, USA; ²Radiology, University of Wisconsin, Madison, Madison, WI, USA; ³Medical Physics and Radiology, University of Wisconsin, Madison, Madison, WI, USA

HYPR FLOW was able to provide 0.69 mm isotropic (.33mm3) spatial resolution with 0.5s frame rate and a 0.75s temporal window for contrast-enhanced information. Although this approach has good resolution and provides flow information and flow derived quantities, it is difficult to reduce voxel volume below about 0.3 mm3 due to the need to acquire four excitations per projection. We present here early results using an alternate hybrid HYPR MRA technique called HYPR TOF in which a separately acquired TOF examination is used to provide a composite image for processing time resolved CE MRA data. Although initially implemented in a stack of stars geometry, this approach when combined with VIPR acquisition will permit greater spatial resolution than HYPR FLOW at the expense of physiological information. This will be important for some aneurysm cases where higher spatial resolution is desirable.