Session ThOE. There are 4 abstracts in this session.

Session: MR SPECTROSCOPY in-vivo and ex-vivo, time: 10:45 - 11:10 am

Fast spectroscopic imaging at 3T and 7T

Jullie Pan1; Victor Yushmanov1; Chan Moon1, 2; Claud Schirda2; Hoby Hetherington1
1University of Pittsburgh, Pittsburgh, PA; 2UPMC, Pittsburgh, PA

In spectroscopic imaging, conventional encoding requires a separate TR for each k-space point, which for moderate or high resolution acquisitions can require more than 15min for a single slice study. With the high SNR now available with UHF systems, encoding methods that are more efficient for spatial encoding are thus advantageous. We discuss and demonstrate implementation of the rosette trajectory for spectroscopic imaging which exhibits flexibility in trajectory design, has excellent efficiency in encoding and reduced gradient demands. Implemented with moderate spin echo and j-refocused sequences, the rosette data demonstrate the characteristic gray matter dependence of creatine and glutamate. The rosette has also been tested in tumor and epilepsy patients to show sensitivity to pathology.

Session: MR SPECTROSCOPY in-vivo and ex-vivo, time: 11:10-11:35

Recent developments in 3T MRS using spectral-editing

Peter Barker1; Kimberly Chan2; Muhammad Saleh1; Georg Oeltzschner1; Richard Edden1
1Johns Hopkins University SOM, Baltimore, Maryland; 2UT Southwestern, Dallas, TX

Spectral editing is a useful technique for measuring compounds such as the inhibitory neurotransmitter GABA or the anti-oxidant glutathione (GSH) in the human brain using 3T MRS. In recent years many clinical or neuroscience edited-MRS studies have been published, usually targeting individual metabolites using single voxel localization techniques. This presentation will review methods for multi-voxel spectral editing (i.e. edited MRSI), both for individual and multiple compounds acquired simultaneously, including the development of a retrospective motion compensation scheme for MRSI in order to reduce subtraction artifacts. 

Session: MR SPECTROSCOPY in-vivo and ex-vivo, time: 11:35 - 12:00

Towards in vivo whole-brain neurochemical fingerprinting at ultra-high field

Wolfgang Bogner
Medical University Vienna, Vienna, Austria

Conventional spin-echo MR spectroscopic imaging (MRSI) techniques cannot fully exploit the benefits that ultra-high field MR scanners (e.g., 7Tesla) offer for in vivo MRSI of the brain. Direct echo-less Free induction decay (FID)- MRSI techniques have emerged as a superior approach that overcomes multiple technical challenges that MRSI has to face beyond clinical field strength (>3 Tesla). The resulting boost in spectral quality can be efficiently translated into much higher spatial resolution, detection of a much more comprehensive neurochemical profile, and that at significantly reduced scan times. This has major implications for the clinical application of in vivo whole-brain MRSI at ultra-high field.

Session: MR SPECTROSCOPY in-vivo and ex-vivo, time: 12:00 - 12:15

Simultaneous Detection of ZQ→DQ and DQ→ZQ Pathways in Phase-Incrementing SSel-MQC (pi-SSelMQC) with Application to Recover Lost Tumor Marker Signals

Qiuhong He; Hong Yuan; Yen-Yu Ian Shih
University of North Carolina, Chapel Hill, North Carolina

A novel phase-incrementing Soft Selective Multiple Quantum Coherence Transfer (pi-SSelMQC) method was developed to detect full Sel-MQC spectroscopic imaging signals of biomarkers with excellent water and lipid suppression.  For demonstration, the pi-SSelMQC experiments were carried out to map lactate spatial distributions in a yogurt phantom and in vivo in murine 344SQ lung tumors grown subcutaneously on the right thigh of syngeneic 129X1/SvJ male mice.  Both ZQ→DQ and DQ→ZQ coherence transfer pathways were detected by synchronizing the phase-encoding gradient steps and RF phase increments of the selective MQ-excitation pulse.  The lactate images from the two different MQ-coherence pathways were detected with opposite imaging offsets away from spurious residual signals of unwanted biochemicals, recovering the 50% lost signal in the original SSel-MQC method.