Application of 3D magnetic resonance microscopy to the anatomy of woody tissues

Abstract

We demonstrate the use of high-resolution three-dimensional magnetic resonance microscopy (3D MRM) for anatomical studies of woody tissues. Samples of normal and pathological structures in the branches of four tree species were imaged by 3D MRM immediately after removal from the tree, without additional tissue preparation. MRM data sets were displayed in 2D sections and in a 3D volume rendered mode. Good image contrasts between identical anatomical structures in different tree species suggest that 3D MRM may be a promising method in comparative wood anatomy. MRM can be used for general morphological observations, as well as for positioning and examination of a particular portion of tissue in the investigated object. This is demonstrated by examples of a needle trace within the xylem in Norway spruce and by localisation of the protection zone at the base of a dead branch in beech. Visualisation of a wound scar in beech demonstrates the efficiency of 3D MRM in revealing the spatial dimensions of any moisture-related structural defects within wood. It can provide relatively high and isotropic resolution, thus enabling non-destructive and accurate determination of the moisture content of any wood structure. High-resolution 3D MRM has great potential in studying the anatomy of woody plants due to the non-destructive nature of the technique, the simplicity of tissue preparation and very versatile information retrieval by choosing an appropriate MRM method and its parameter set.