Reducing gradient imperfections for spiral magnetic resonance spectroscopic imaging.

Spiral k-space magnetic resonance spectroscopic imaging (MRSI) requires high performance from gradient hardware systems. During the readout phase, oscillating gradients are continuously played out, which can cause undesired effects. These effects on the quality of SI data are non-intuitive because of their time-varying nature. In this work we describe the effects of undesirable gradient performance on SI. Measurements of the true readout trajectories were performed and the results were then used in the reconstruction process. The effects of these imperfections resulted in a spatially and spectrally varying amplitude and frequency modulation. The use of the measured trajectories in the reconstruction process yielded an up to 20% increase in signal amplitude recovery. Copyright (c) 2006 Wiley-Liss, Inc.