Towards 1H-MRSI of the human brain at 7T with slice-selective adiabatic refocusing pulses.
OBJECTIVE
To explore the possibilities of proton spectroscopic imaging (1H-MRSI) of the human brain at 7 Tesla with adiabatic refocusing pulses.


METHODS
A combination of conventional slice selective excitation and two pairs of slice selective adiabatic refocusing pulses (semi-LASER) results in the formation of an echo from a localized volume. Depending on the used radio frequency (rf) coil efficiency and available rf power, the duration of the adiabatic full passage pulses (AFPs) is adapted to enable echo times down to 50 ms (head coil) or 30 ms (local surface coil).


RESULTS
An AFP duration of 5 ms with a corresponding bandwidth of 5.1 kHz resulted in a chemical shift displacement error of 23% over 3.8 ppm at 7T. Using a local surface coil and an echo time down to 30 ms, we detected not only the three main metabolites (NAA, Cr and Cho), but also coupled signals from myo-inositol and glutamate/glutamine in spectra from 0.14 cc voxels with linewidths down to 10 Hz in 10 min measurement time.


CONCLUSIONS
The semi-LASER pulse sequence enables 1H-MRSI of the human brain at 7T for larger parts of the brain as well as small localized areas with both a high spectral and spatial resolution.
Scheenen
Tom W J
TW
Department of Radiology (667), University Medical Center, Nijmegen Geert Grooteplein 10, 6525 GA, Nijmegen, The Netherlands. T.Scheenen@rad.umcn.nl
Heerschap
Arend
A
Klomp
Dennis W J
DW
D000465:Algorithms; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods; D003952:Diagnostic Imaging / Q000379:methods; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D015233:Models, Statistical; D009821:Oils; D019047:Phantoms, Imaging; D011846:Radio Waves; D015203:Reproducibility of Results; D013997:Time Factors; D051598:Whole Body Imaging
D009821:Oils