JAS MR Spectroscopy Program:
Proton Magnetic Resonance Spectroscopy (MRS)
The principles of magnetic resonance were used to measure chemical structure and composition
for over 30 years prior to their use in the development of MRI. With the availability of capable
clinical MRI/MRS systems, and techniques to readily isolate chemical
measurements to specific regions in the brain, practical in vivo measurements of tissue
metabolite levels are available for the study of normal and pathological processes.
The basic capabilities of the MRI/MRS system have been augmented by a large number of
acquisition sequences and procedures that allow high quality localized metabolite spectra to be
obtained within the duration of a normal imaging examination. Full facilities for acquisition and
processing of single-voxel (SVS) and 1D or 2D spectroscopic imaging (MRSI) data are
available. The MRS techniques are used in several research programs at the Facility.
As expected, Facility work in MRS applies primarily to the brain. However, similar technology is applied
to other organ systems where work correlating morphological and
biochemical changes with drug treatment can be used as a model for brain tumor radiation or
There are currently two main focuses for the MRS brain research at the Facility. The first is in
the measurement of the biochemical characteristics of primary and metastatic brain tumors. The
unique characteristics of tumor spectra have been demonstrated during the course of our
participation in multicenter MRS clinical trials.
The extension of that work is
currently towards the evaluation of MRS as an effective tool for discrimination between tumor
recurrence and the effects of radiation treatment. This is often a difficult clinical decision as
there may be similar MRI image appearance. The results of MRS examination of clinical
patients is being correlated with those from SPECT in order to determine the effectiveness of
MRS as a routine clinical tool in these cases.
Additional work is underway applying these techniques to study stroke, white-matter diseases, and traumatic brain injury.
The second MRS focus employs functional localization, typically by MEG, to identify regions of
interest for further biochemical interrogation by MRS. With current procedures, MRS or MRSI
metabolite information cannot practically be obtained throughout the head at the same resolution
as MRI image information. The functional localization is used to identify a smaller region of
interest where MRS measurements can be made more efficiently. The information obtained
provides insight into the biochemical processes accompanying neural activation of normal and
abnormal brain regions.
Current research at the Facility is investigating the biochemical processes in the tissue at the
epileptic seizure focus identified by MEG. The results of this study will help validate MEG
localization in these cases, correlate metabolite levels with electrophysiological changes, and give insight into the effectiveness of MRS as a focus localization modality with and without MEG guidance.
Technical development and experimental research is ongoing to improve MRS spatial resolution
(eg combined SVS and MRSI acquisitions), quality (e.g., rf pulse design and water suppression
methods), analysis (e.g., signal processing procedures), and clinical application (e.g., automated
Last Modified: July 14, 1999
Copyright 1999 John A Sanders, VAMC