Method of efficient data encoding in dynamic magnetic resonance imaging

Abstract

MRI is used to monitor the time behavior or an organ of interest. Images of such organ may change in time due to physiological motion, and/or due to contrast-agent accumulation. Dynamic applications generally involve acquiring data in a k-t space, which contains both temporal and spatial information. In some dynamic applications, the t axis of the k-t space is not densely filled with information. A method is introduced which can transfer information from the k axes to the t axis, allowing a denser, smaller k-t space to be acquired, and leading to significant reductions in the acquisition time of the temporal frames. Results are presented for cardiac imaging and functional MRI (fMRI). In the case of cardiac imaging, the present method is shown to reduce the data requirement by nearly a factor two. In the case of fMRI, reductions by as much as a factor six can be obtained. The behavior of the method is assessed by comparing the results to data obtained in a conventional way. Of course, the reductions in imaging time lead to the expected reductions in SNR. The present method can be used to significantly reduce the acquisition time of the individual temporal frames in certain dynamic studies. This can be used, for example, to increase the temporal and/or spatial resolution, increase the spatial coverage, decrease the total imaging time, or alter sequence parameters (e.g., TR and TE) and thereby alter contrast, depending on the circumstances.