Accelerated cardiac T2 mapping using breath‐hold multiecho fast spin‐echo pulse sequence with k‐t FOCUSS

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Abstract
Cardiac T2 mapping is a promising method for quantitative assessment of myocardial edema and iron overload. We have developed a new multiecho fast spin echo (ME‐FSE) pulse sequence for breath‐hold T2 mapping with acceptable spatial resolution. We propose to further accelerate this new ME‐FSE pulse sequence using k‐t focal underdetermined system solver adapted with a framework that uses both compressed sensing and parallel imaging (e.g., sensitivity encoding) to achieve higher spatial resolution. We imaged 12 control subjects in midventricular short‐axis planes and compared the accuracy of T2 measurements obtained using ME‐FSE with generalized autocalibrating partially parallel acquisitions and ME‐FSE with k‐t focal underdetermined system solver. For image reconstruction, we used a bootstrapping two‐step approach, where in the first step fast Fourier transform was used as the sparsifying transform and in the final step principal component analysis was used as the sparsifying transform. When compared with T2 measurements obtained using generalized autocalibrating partially parallel acquisitions, T2 measurements obtained using k‐t focal underdetermined system solver were in excellent agreement (mean difference = 0.04 msec; upper/lower 95% limits of agreement were 2.26/−2.19 msec, respectively). The proposed accelerated ME‐FSE pulse sequence with k‐t focal underdetermined system solver is a promising investigational method for rapid T2 measurement of the heart with relatively high spatial resolution (1.7 × 1.7 mm2). Magn Reson Med, 2011.
Funding Information
  • National Institutes of Health (R01-DK069373, R01-EB000447-07A1)
  • American Heart Association (0730143N)
  • Korea Science and Engineering Foundation (2009-0081089)