TY  - JOUR
AU  - Homan, N. M.
AU  - Windt, Carel
AU  - Vergeldt, F. J.
AU  - Gerkema, E.
AU  - Van As, H.
TI  - 0.7 and 3 T MRI and Sap Flow in Intact Trees: Xylem and Phloem in Action
JO  - Applied magnetic resonance
VL  - 32
IS  - 1
SN  - 1613-7507
CY  - Wien [u.a.]
PB  - Springer
M1  - FZJ-2016-00369
SP  - 157 - 170
PY  - 2007
AB  - Dedicated magnetic resonance imaging (MRI) hardware is described that allows imaging of sap flow in intact trees with a maximal trunk diameter of 4 cm and height of several meters. This setup is used to investigate xylem and phloem flow in an intact tree quantitatively. Due to the fragile gradients in pressure present in both xylem and phloem, methods to study xylem and phloem transport must be minimally invasive. MRI flow imaging by means of this hardware certainly fulfils this condition. Flow is quantified in terms of (averaged) velocity, volume flow (flux) and flow conducting area, either in imaging mode or as a nonspatially resolved total. Results obtained for one tree, imaged at two different field strengths (0.7 and 3 T), are compared. An overall shortening of observed T 2 values is manifest going from 0.7 to 3 T. Although some susceptibility artefacts may be present at 3 T, the results are still reliable and the gain in sensitivity results in shorter measurement time (or higher signal-to-noise ratio) with respect to the 0.7 T system. The results demonstrate that by use of dedicated hardware, xylem and phloem flow and its mutual interaction, can be studied in intact trees in relation to the water balance and in response to environmental (stress) conditions.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000249319500010
DO  - DOI:10.1007/s00723-007-0014-3
UR  - https://juser.fz-juelich.de/record/280601
ER  -