Reduction of MR imaging time by the hybrid fast-scan technique.

The time taken to collect high-resolution and high signal-to-noise (S/N) data in magnetic resonance (MR) imaging may be the limiting factor in patient throughput and in reducing patient motion. A hybrid fast-scan technique combining static and oscillatory phase-encoding gradients from two-dimensional Fourier transform (2DFT) and echo-planar imaging can reduce the time needed to collect data at the expense of loss in S/N. The flexibility of this technique is that any amplitude or frequency of oscillation of the phase-encoding gradient can be used. The technique was used for different frequencies and amplitudes, and images are presented that were acquired in one-half and one-quarter the time required with standard 2DFT techniques. The images illustrate that the hybrid and 2DFT techniques produce comparable resolution and contrast under identical conditions.