Electric Current Density Imaging of Pedunculate Oak(Quercus RoburL.) Twigs by Magnetic Resonance Imaging

Abstract

The use of Electric Current Density Imaging (CDI) technique to map spatial distribution of induced electric currents through two years old twigs of pedunculate oak (Quercus robur L.) is presented. Specifically, this magnetic resonance technique was implemented to image conductivity contrast in different tree tissues. Imaged electric conductivity distributions of pith, wood, and phloem together with cambial zone and undifferentiated xylem were compared with flame atomic absorption spectrometry measurements of potassium. Good correlation was observed. The undifferentiated xylem + cambial zone + complete phloem showed higher electrical conductivity and normalized potassium values than both differentiated xylem and pith. By a novel magnetic resonance imaging technique it is demonstrated that the path of least resistance to an electric current was along tissues of maximum free potassium concentration.

Three-dimensional in vivo magnetic resonance microscopy of beech (Fagus sylvatica L.) wood

“…Large clinical magnet openings enabled imaging of quite large pieces of wood (logs of diameter 15 cm and more) but the spatial resolution of those images was relatively low (typical in-plane resolution was approximately 1 mm). The images showed separation of the sapwood and heartwood, delineation of growth rings, the pith and rays [4][5][6][7]. In addition to normal features, MRI also revealed internal defects of wood [8].…”

Magnetic Resonance Current Density Imaging of Chemical Processes and Reactions

“…is a function of the concentration of mobile ions (6,8). Another example is a chemical reaction, where calcium carbonate was produced and dissolved in hydrochloric acid to form calcium chloride.…”

“…The technique has already been successfully used on tumors and bones, which shows its potential medical applications (3)(4)(5). Correlation of current density to ionic concentration has been studied on wood samples (6). One of the possible nonmedical applications is the characterization of inorganic chemical processes and reactions (for example ionic reactions, including acid-base neutralizations and reactions that produce precipitates or gases), which change the conductivity by changing the concentration of ions in a solution (7).…”

Current density imaging sequences with separation of mobile-ion current from immobile-ion current

“…Applications of CDI include: technology, where CDI can be used to follow electro-osmotic flow [9,10] or to study electric currents in models of porous materials [11,12]; chemistry, where CDI can be used to monitor chemical reactions that release ions [13]; forestry, where living conditions of trees are associated with the level of potassium ions and with it related conductivity [14]; and biology and medicine, where wide spread applications may be found. A few of these applications are defibrillation [15], electroporation [16], bone fracture healing by currents [17], studying electrically induced skin burns [18], specific radiofrequency absorption rate (SAR) distribution measurements [19] and studying brain conductivity changes during transcranial stimulation [20] or spreading depression [21].…”