MAGMA (2005) 18: 171–174 DOI 10.1007/s10334-005-0109-5 SHORT COMMUNICATION M. Merela A. Sepe P. Oven I. Serˇ sa Three-dimensional in vivo magnetic resonance microscopy of beech (Fagus sylvatica L.) wood Received: 21 March 2005 Accepted: 25 May 2005 Published online: 29 July 2005 © ESMRMB 2005 M. Merela · P. Oven Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana 1000, Slovenia A. Sepe · I. Serˇ sa (B ) Condensed Matter Physics Department, Joˇ zef Stefan Institute, Jamova 39, Ljubljana 1000, Slovenia, E-mail: igor.sersa@ijs.si Tel.: +386-1-4773696 Fax: +386-1-4773191 Abstract Spatial structure and water distribution in branch tissues after mechanical injury were investigated in vivo by three-dimensional (3D) magnetic resonance (MR) microscopy. On a beech tree (Fagus sylvatica L.), transplanted in a portable pot, a branch was topped and then MR imaged. High-resolution 3D MR images revealed structures which could not be identified by conventional MR images or by light microscopy. MR measurements confirmed our assumption that moisture content is decreasing towards the wounded part of the branch. This indicates that quick moisture loss from mechanically wounded tissues represents the initial passive response of compromised tissue. Keywords Magnetic resonance microscopy · Water distribution · Wood · Fagus sylvatica Introduction Wood is an engineering material, defined as a low-density, cellular, hygroscopic, polymeric composite [1]. It is a bio- logical end product of trees [2]. In a botanical sense, wood is secondary xylem generated during episodic cambial growth, restricted to warm spring and summer months in temperate regions. A new growth mantel of wood is depos- ited upon the existing wood of roots, branches and stem of a tree every growing season. Wood comprises living, ageing, dying and dead cells [3]. Xylem tissue fulfils con- ductive, storage and supportive functions in living trees. This is possible due to functionally specialized cells ar- ranged in axial and radial directions. Magnetic resonance imaging (MRI) is a promising non-destructive technique for imaging internal features of wood. First MRI experiments on wood, done over 30 years ago, had shown that wood can be successfully imaged by MRI because of high moisture content. First magnetic res- onance (MR) images of wood were two dimensional (2D) and were acquired on standard clinical MRI scanners with relatively low magnetic fields (0.15–1T). Large clinical magnet openings enabled imaging of quite large pieces of wood (logs of diameter 15 cm and more) but the spatial res- olution of those images was relatively low (typical in-plane resolution was approximately 1mm). The images showed separation of the sapwood and heartwood, delineation of growth rings, the pith and rays [4–7]. In addition to nor- mal features, MRI also revealed internal defects of wood [8]. Knots, eccentricity and irregularities were confirmed by computer reconstruction of pine growth rings imaged by MRI [9]. MRI was also used for non-invasive dynamic studies of plant–pathogen interactions [10] and qualita- tive and quantitative studies of wood-drying kinetics [11]. MRI excels by its non-destructiveness, it is a non-contact method and is relatively fast; it can be used in situ and in vivo and does not induce any structural damage [12]. The aim of this research was to test feasibility of three-dimensional (3D) MR microscopy for morpholog- ical imaging and for non-destructive characterization of