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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Magnetic resonance materials in physics, biology and medicine 2 (1994), S. 79-89 
    ISSN: 1352-8661
    Keywords: mr imaging ; relaxation times ; proton density ; double delay multiecho ; high resolution parameter images ; tissue characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics
    Notes: Abstract A new magnetic resonance imaging high-resolution sequence is presented that allows for the collection of all data for determination ofT 1 and ρ as well as for multiexponentialT 2 analysis within one measurement cycle. Noise preprocessing is performed in order to avoid systematic errors in relaxation parameter analysis and to increase the interexperimental reproducibility of the results. ForT 2 analysis, an optimized Marquardt algorithm is used, in combination with image processing methods for both automatic detection of voxels with partial volume effects, and for speedup of the iterative nonlinear regression steps. Determination of longitudinal relaxation time is based on a sophisticated signal intensity ratio technique that computesT 1 as the mean of up to eight individualT 1 values, each weighted with its relativeT 2 decay. Relative proton density is computed using results of the evaluations of both relaxation times. Validation of the method is accomplished by comparing phantom measurements with reference data acquired with spectroscopic sequences.In vivo examples of the computed parameter images taken from a study of experimental cerebral infarcts in rats are presented. The method allows one to acquire high-resolution parameter images within a measurement time that is tolerable even in clinical routine. Furthermore, the chosen evaluation concepts guarantee a short computation time. Therefore, an on-line computation of the parameter images and, in consequence, their direct use for diagnostic purposes appears feasible.
    Type of Medium: Electronic Resource
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