3D high temporal and spatial resolution contrast‐enhanced MR angiography of the whole brain

Abstract

Sensitivity encoding (SENSE) and partial Fourier techniques have been shown to reduce the acquisition time and provide high diagnostic quality images. However, for time‐resolved acquisitions there is a need for both high temporal and spatial resolution. View sharing can be used to provide an increased frame rate but at the cost of acquiring spatial frequencies over a duration longer than a frame time. In this work we hypothesize that a CArtesian Projection Reconstruction‐like (CAPR) technique in combination with 2D SENSE, partial Fourier, and view sharing can provide 1–2 mm isotropic resolution with sufficient temporal resolution to distinguish intracranial arterial and venous phases of contrast passage in whole‐brain angiography. In doing so, the parameter of “temporal footprint” is introduced as a descriptor for characterizing and comparing time‐resolved view‐shared pulse sequences. It is further hypothesized that short temporal footprint sequences have higher temporal fidelity than similar sequences with longer temporal footprints. The tradeoff of temporal footprint and temporal acceleration is presented and characterized in numerical simulations. Results from 11 whole‐brain contrast‐enhanced MR angiography studies with the new method with SENSE acceleration factors R = 4 and 5.3 are shown to provide images of comparable or higher diagnostic quality than the unaccelerated reference. Magn Reson Med 60:749–760, 2008.