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Keywords:

  • T2 relaxometry;
  • undersampling;
  • k-t BLAST;
  • k-t GRAPPA;
  • SPIO labeled cells

Abstract

A new method has been developed to reduce the number of phase-encoding steps in a multi-echo spin-echo imaging sequence allowing fast T2 mapping without loss of spatial resolution. In the proposed approach, the k-space data at each echo time were undersampled and a reconstruction algorithm that exploited the temporal correlation of the MR signal in k-space was used to reconstruct alias-free images. A specific application of this algorithm with multiple-receiver acquisition, offering an alternative to existing parallel imaging methods, has also been introduced. The fast T2 mapping method has been validated in human brain T2 measurements in a group of nine volunteers with acceleration factors up to 3.4. The results demonstrated that the proposed method exhibited excellent linear correlation with the regular T2 mapping with full sampling and achieved better image reconstruction and T2 mapping with respect to SNR and reconstruction artifacts than the selected reference acceleration techniques. The new method has also been applied for quantitative tracking of injected magnetically labeled breast cancer cells in the rat brain with acceleration factors of 1.8 and 3.0. The proposed technique can provide an effective approach for accelerated T2 quantification, especially for experiments with single-channel coil when parallel imaging is not applicable. Copyright © 2010 John Wiley & Sons, Ltd.