Accelerating time-resolved MRA with multiecho acquisition.

A new four-dimensional magnetic resonance angiography (MRA) technique called contrast-enhanced angiography with multiecho and radial k-space is introduced, which accelerates the acquisition using multiecho while maintaining a high spatial resolution and increasing the signal-to-noise ratio (SNR). An acceleration factor of approximately 2 is achieved without parallel imaging or undersampling by multiecho (i.e., echo-planar imaging) acquisition. SNR is gained from (1) longer pulse repetition times, which allow more time for T(1) regrowth; (2) decreased specific absorption rate, which allows use of flip angles that maximize contrast at high field; and (3) minimized effects of a transient contrast bolus signal with a shorter temporal footprint. Simulations, phantom studies, and in vivo scans were performed. Contrast-enhanced angiography with multiecho and radial k-space can be combined with parallel imaging techniques such as Generalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) to provide additional 2-fold acceleration in addition to higher SNR to trade off for parallel imaging. This technique can be useful in diagnosing vascular lesions where accurate dynamic information is necessary. (c) 2010 Wiley-Liss, Inc.