NMR imaging of white button mushroom (Agaricus bisporis) at various magnetic fields

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) have been applied to visualize physiological phenomena in plants and agricultural crops, Imaging sequences that result in contrast of a combination of parameters (e.g., proton density, T-1, T-2, T-2*) cannot be used for a correct and unique interpretation of the results, In this study multiecho imaging together with monoexponential T-2 decay fitting was applied to determine reliable proton density and T-2 distributions over a mushroom, This was done at three magnetic field strengths (9.4, 4.7, and 0.47 T) because susceptibility inhomogeneities were suspected to influence the T-2 relaxation times negatively, and because the influences of susceptibility inhomogeneities increase with a rise in magnetic field strength, Electron microscopy was used to understand the different T-2's for the various tissue types in mushrooms, Large influences of the tissue ultrastructure on the observed T-2 relaxation times were found and explained, Based on the results, it is concluded that imaging mushrooms at low fields (around or below 0.47 T) and short echo times has strong advantages over its high-field counterpart, especially with respect to quantitative imaging of the water balance of mushrooms, These conclusions indicate general validity whenever NMR imaging contrast is influenced by susceptibility inhomogeneities. Copyright (C) 1996 Elsevier Science Inc.