Fast k-space sample selection in MRSI with a limited region of support

One of the primary drawbacks in the application of magnetic resonance spect roscopic imaging is the long acquisition times required to obtained the des ired resolution. When region of support information is available, the numbe r of phase-encoding steps and thus time can be reduced without loss of info rmation if the k-space locations are chosen well. We propose to select loca tions using a rectangular sampling array that is shifted to various positio ns in k-space to obtain the necessary sampling density. This method allows multiple samples to be selected simultaneously and reduces the computation required to evaluate the selection criterion. We present an efficient forwa rd selection algorithm for optimizing the shift pattern so that the image c an be reconstructed as reliably as possible from a periodic nonuniform set of samples. The proposed algorithm has important practical potential in tha t it can finish the selection in less than half a minute for typical image sizes and can reconstruct the image with fewer samples than regular samplin g. With appropriate imaging hardware, this new algorithm makes selective sa mpling possible in a real-time image acquisition setting.