deutsch

Overview Features Measured Parameters Applications References Resources Support Hardware Disclaimer Contact

medeaLAB Tracking application: Tracking the tail fin of swimming fish Sample object: Marine fish   Tracking of fish fins During MR measurements in swimming marine fish the tail fin (with marking) was tracked. Tracking fish fin with medeaLAB Reference: Bock, C., Pörtner, H. -O., Webber, D. M., Wittig, R., Junge, S., "An insulated three coil set-up for MR studies on swimming fish operating in seawater." Proc. Intl. Soc. Mag. Reson. Med. 10(2002): 871-871. Abstract: Heavy loading, strong RF loss and the skin effect complicate MR investigations in electric conductive, dielectric media. A set-up was developed for MR studies on swimming marine fish that reduces these limitations. A birdcage resonator adapted to high loadings was used for signal excitation. An insulated inductive coil (2 cm diameter) was fixed onto the fish and placed opposite to a watertight, passively decoupled 5 cm surface coil for signal reception. This arrangement led to enhanced penetration of the RF signal and an almost 10-fold increase in S/N ratio compared to the exclusive use of the 5 cm surface coil. MR measurements in electric conductive, dielectric media are complicated mainly by inductive losses. These losses originate from eddy currents induced within the sample by the oscillating field B,. The electric conductivity decreases the signal-to-noise ratio (S/N), the loading in a coil rises. Also, pulse length or power to produce a given pulse angle increases, whereas the irradiation of radio frequencies (RF) attenuates due to the skin effect. These strong effects might even be intensified when an electric conductive medium like sea-water is flowing through an NMR probe. In this study, we present an approach for the development of an RF-coil set-up for MR measurements camed out in swimming marine fish in a horizontal MR scanner.