Ultrafast interleaved gradient-echo-planar imaging on a standard scanner.

Ultra-fast imaging traditionally implies either echo-planar imaging on specially developed gradient systems, or very short repetition time gradient-echo imaging on standard magnetic resonance imaging scanners. An alternative strategy for very fast imaging with conventional whole-body scanners is discussed here. The technique is a hybrid, whereby the advantages of gradient-echo imaging and echo-planar imaging are combined. It is here denoted interleaved gradient-echo-planar imaging. It is not a single specific measurement sequence, but rather a continuum of sequences whereby multiple excitations with multiple gradient-echos are employed. The power of this fast imaging approach is that one has much more flexibility toward the optimization of the measurement sequence with respect to imaging time, T2 relaxation, gradient power, resolution, image distortion, and signal-to-noise ratio. In vivo human heart images, acquired in 110 ms, and with a resolution of 2.5 mm, have been obtained with a standard whole-body scanner.