Discrete and Continuous Spin-Spin Relaxation Rate Distributions Derived from CPMG NMR Response Curves: a Comparative Analysis Exemplified by Water in Meat

作者：Hansen Eddy W^*; Zhu Han

来源：Applied Magnetic Resonance, 2016, 47(11): 1255-1272.

DOI：10.1007/s00723-016-0828-y

The spin-spin relaxation rate distribution of water in a porcine longissimus dorsi muscle was derived from an inverse integral transformation of the proton CPMG (Carr-Purcell-Meiboom-Gill) NMR (nuclear magnetic resonance) signal at each hour during a 49 h drip period. This "continuous (C)" relaxation rate distribution was found to be excellently represented by an empirical peak function, characterized by three parameters: a peak width, an average relaxation rate, and a skewness parameter, which enable the distribution to be quantitatively defined. In addition, the same CPMG response was fitted to a sum of three single-exponential decay functions, denoted a "discrete (D)" relaxation rate model. The analysis shows that when the fraction of the slow relaxation component from the continuous model is close to 5 %, which is a rather typical value, the mean relaxation rate from the discrete model becomes larger than the corresponding relaxation rate from the continuous model by nearly 25 % and becomes larger than by more than 75 %. Likewise, when approaches 2.5 %, becomes larger than by more than 75 % and becomes larger than by more than a factor of 3 which are supported by model simulations. The relative quality and goodness of the two different relaxation rate models are discussed. Finally, the number of transients needed to obtain a preset error in relaxation rate and/or mole fraction was determined by model simulation.

• 出版日期2016-11