Integrated RF probe for in vivo multinuclear spectroscopy and functional imaging of rat brain using an 11.7 Tesla 89 mm bore vertical microimager

Abstract

To acquire high quality in vivo NMR data from rat brain using a vertical 89-mm bore magnet, specially designed NMR probes with integrated RF coils and animal handling capability are required. An RF probe design that is also capable of rat head fixation, body support and suitable for physiology monitoring and maintenance was constructed for an 89 mm bore, 11.7 T, vertical microimager which is equipped with a 57-mm i.d. gradient insert. Design concept and practical aspects of probe construction are described in detail. The device allows accurate and highly reproducible positioning of rat head inside the magnet while providing excellent RF performance. Typical results from fMRI, localized in vivo proton and multinuclear spectroscopy using this probe system are presented.

In vivo dynamic turnover of cerebral 13C isotopomers from [U–13C]glucose

“…Recently, this type of magnets, which are widely available and relatively cost-effective compared to the wider and horizontal bore magnets, have been increasingly used to image mice and small rats. Recently, we have demonstrated in vivo proton and POCE MRS data of excellent quality using a vertical, 89-mm bore magnet at 11.7 Tesla, the highest field strength at which in vivo spectroscopy of rodent brain has ever been attempted [27,31,32]. The results of current report extend the usefulness of vertical, 89-mm bore magnets to include in vivo localized 13 C MRS.…”

“…The lower end of the system was an aluminum interface box through which RF cables, ventilation tubes, rectal thermal probe, and catheters were connected. A similar design of the RF probe/animal handling system for proton and Proton-Observed, Carbon-13-Edited spectroscopy experiments of rat brain using the vertical 89-mm bore magnet was descried previously [27]. The RF probe/ animal handling system is suitable for rat head fixation, body support, physiology maintenance, coil tuning and RF shielding.…”

“…The RF probe/ animal handling system is suitable for rat head fixation, body support, physiology maintenance, coil tuning and RF shielding. It allows maintenance of normal physiology over prolonged period despite of increased cardiac load and blood draining associated with vertically positioned rats [27]. It is mechanically interfaced to the magnet using an adaptor ring which allows vertical and angular position adjustments.…”

In vivo 13C saturation transfer effect of the lactate dehydrogenase reaction

“…The integrated RF coils/head-holder system is capable of rat head fixation (with ear pins and a bite bar), body support, physiology maintenance, coil tuning, and RF shielding. Similar designs of the RF probe/animalhandling system for proton and proton-observed, carbon-13-edited spectroscopy experiments of rat brain using the vertical 89-mm bore magnet have been described recently (20).…”

Inverse polarization transfer for detecting in vivo 13C magnetization transfer effect of specific enzyme reactions in 1H spectra

“…The magnet is equipped with a 57-mm inner diameter gradient (Mini0.5, Bruker Biospin, Billerica, MA, with a maximum gradient strength of 3.0 G/mm and a rise time of 100 μs). The RF probe/animal handling system for the 13 C-to-1 H heteronuclear polarization transfer spectroscopy experiments of rat brain using the vertical 89-mm bore magnet have been described recently [21]. Briefly, the inner circular loop is the 1 H coil with an inner diameter of 15 mm and a conductor width of 2.5 mm.…”