# Proton magnetic resonance spectroscopy
Proton magnetic resonance spectroscopy is a magnetic resonance technique that measures hydrogen signals from metabolites in body tissue, rather than from water, to assess biochemical composition for diagnosis. Its imaging form, [magnetic resonance spectroscopic imaging](https://www.edgepedia.org/magnetic-resonance-spectroscopic-imaging) (MRSI), acquires spectra from many voxels at once. In the brain, the method detects N-acetyl aspartate, glutamate, glutamine, creatine and phosphocreatine, choline-containing compounds, taurine, and inositols, with cerebral lactate normally at or below roughly 0.5 mM when NAA in white matter is taken as 6 mM.[1](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910090110) Malignant brain and prostate tumors show increased choline, and brain tumors show decreased NAA and creatine, which underlies the choline-to-NAA index as a cancer biomarker and the (choline+creatine)/citrate ratio as a prostate biomarker.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/)
| Key fact | Value |
|---|---|
| Main brain metabolite shifts | NAA 2.01 ppm; creatine 3.03, 3.91 ppm; choline 3.21 ppm; lactate 1.31 ppm[3](https://link.springer.com/article/10.1007/s00249-009-0517-y) |
| Water-to-metabolite concentration gap | Bulk water about 70 M versus 1–10 mM metabolites, roughly 10,000-fold[4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en) |
| Single-voxel sequences | STEAM: shortest TE ≈20 ms; PRESS: shortest TE ≈30 ms with twice the signal[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) |
| Typical 2D MRSI at 3 T | 16×16 grid, ~1.5 cm³ voxels, ~5 min at TR 1500 ms[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) |
| Tumor diagnosis | ~90% accuracy for pairwise adult tumor type comparison; 78% for glioblastoma versus metastasis[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531) |
| Quantification | LCModel fits the spectrum as a linear combination of model metabolite spectra[7](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910300604) |
| Acceleration | Compressed-sensing reconstruction can cut MRSI acquisition time by up to 80% or more[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/) |
## How it works
The method exploits chemical shift: nuclei in different molecular environments resonate at slightly different frequencies, expressed as \( \delta_{x} = (\nu_{x} - \nu_{\mathrm{ref}})/\nu_{\mathrm{ref}} \times 10^{6} \) in parts per million, so peak separations are independent of field strength, with water as the usual ¹H reference.[8](https://www.aapm.org/meetings/amos2/pdf/49-14586-98296-721.pdf) A scanner resolves peaks that differ by only a few ppm because the signal is sampled for hundreds of milliseconds; spectral resolution in Hz equals the reciprocal of the acquisition duration, so an 819.2 ms acquisition gives 1.2 Hz resolution.[4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en)
Two physical facts shape every acquisition. First, J-coupling, a through-bond interaction between adjacent proton spins, splits peaks of lactate, glutamate, glutamine, myo-inositol, GABA, and glutathione.[4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en) Second, bulk water is about 10,000 times more concentrated than brain metabolites (about 70 M versus 1–10 mM)[4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en), so water suppression is mandatory, typically with chemical-shift-selective (CHESS) pulses centered at 4.7 ppm, with VAPOR and WET as alternatives.[4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en)
## How it is done
The practitioner places a voxel on anatomical images, shims the static field, suppresses water, and runs a localization sequence. In STEAM, three slice-selective 90° pulses excite three intersecting slices and produce a stimulated echo, with water suppression by preceding CHESS pulses.[1](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910090110) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) In PRESS, a 90° excitation pulse followed by two 180° refocusing pulses on orthogonal gradients defines the voxel, and only magnetization in the intersection refocuses; PRESS is more commonly used because its spin echo gives twice the STEAM signal.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) • [4](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en) Consensus recommendations favor the shortest achievable echo time for single-voxel studies, with chemical shift displacement within 4% per ppm, TR of 1.5 s at 1.5 T and 2.0 s at 3 T; for 2D MRSI the default is a 16×16 matrix with elliptical k-space sampling, 10 mm in-plane resolution, and 15 mm slice thickness.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/)
Echo time determines which metabolites appear. Short TEs of 20–30 ms improve detection of J-coupled metabolites (glutamine, glutamate, myo-inositol) but enhance broad macromolecule and lipid signals; TE of 144 or 288 ms is commonly used to discriminate lactate from lipids, and TE near 135 ms inverts the lactate peak.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) • [8](https://www.aapm.org/meetings/amos2/pdf/49-14586-98296-721.pdf) [Voxel](https://www.edgepedia.org/voxel) size trades signal against specificity: an 8 cm³ voxel gives high-quality spectra at 1.5 T in 5 minutes, volumes down to 4 cm³ allow quantification beyond tNAA, tCr, and tCho at 3 T, and volumes below 4 cm³ lack adequate signal-to-noise ratio.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) Quantification is usually performed with LCModel, which analyzes the spectrum as a linear combination of model spectra of metabolite solutions in vitro, with constrained regularization for phase, baseline, and lineshape differences, and is fully automatic.[7](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910300604)
## Origin
[In vivo magnetic resonance spectroscopy](https://www.edgepedia.org/in-vivo-magnetic-resonance-spectroscopy) began with phosphorus-31: D. I. Hoult and colleagues observed tissue metabolites in intact tissue by ³¹P NMR in 1974 in Nature[9](https://doi.org/10.1038/252285a0), and localization followed with topical magnetic resonance (R. E. Gordon and colleagues, 1980)[10](https://doi.org/10.1038/287736a0) and surface-coil mapping (Joseph J. H. Ackerman and colleagues, 1980).[11](https://doi.org/10.1038/283167a0) Localized solvent-suppressed ¹H spectroscopy in humans was reported by P. A. Bottomley and colleagues in 1985 in PNAS.[12](https://doi.org/10.1073/pnas.82.7.2148) The method itself, localized proton spectroscopy using stimulated echoes (STEAM), was introduced by Jens Frahm, Klaus-Dietmar Merboldt, and Wolfgang Hänicke in 1987 in the Journal of Magnetic Resonance.[13](https://doi.org/10.1016/0022-2364%2887%2990154-5) Frahm, Merboldt, and Hänicke obtained high-resolution ¹H spectra of the human brain on a conventional 1.5-T whole-body MRI system in 1989, using 64 ml (4×4×4 cm³) occipital voxels and measuring times from 1 s to about 10 min.[1](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910090110) MRSI originated as three-dimensional chemical shift imaging, reported by T. R. Brown, B. M. Kincaid, and K. Ugurbil in 1982 in PNAS.[14](https://doi.org/10.1073/pnas.79.11.3523)
## Variants
[Single-voxel spectroscopy](https://www.edgepedia.org/single-voxel-spectroscopy) (SVS) acquires one spectrum with the best achievable quality; MRSI (originally chemical shift imaging) phase-encodes spectra across a grid, trading scan time and shimming difficulty for spatial coverage.[8](https://www.aapm.org/meetings/amos2/pdf/49-14586-98296-721.pdf) Echo-planar spectroscopic imaging gains an acceleration factor equal to the spatial matrix dimension, so a 16×16 matrix takes 16 times less time than conventional chemical shift imaging, possibly at the cost of signal-to-noise ratio and with Nyquist ghost artifacts.[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/) Field strength matters: up to 18 metabolites can be quantified at short echo times at 7.0 or 9.4 T[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531), where enhanced spectral dispersion supports visualization of lactate, lipid, glutamate, glutamine, glutathione, glycine, and 2-hydroxyglutarate.[15](https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2026.1746678/full) At 3 T, a head-to-head comparison with identical ~5-minute scan times found semi-LASER SVS quantified 17 neurochemicals with Cramér-Rao lower bounds under 20% versus 11 for short-TE spiral MRSI, though seven major metabolites were reliably quantified by both.[16](https://www.ovid.com/journals/mrim/fulltext/10.1002/mrm.70463~short-echo-time-spiral-mrsi-versus-single-voxel-spectroscopy) Specialized sequences target coupled metabolites: double DANTE-PRESS simultaneously refocuses glutamate at 2.35 ppm and glutathione at 3.77 ppm at 7 T without spectral editing.[17](http://onlinelibrary.wiley.com/doi/10.1002/nbm.70385) [Compressed sensing](https://www.edgepedia.org/compressed-sensing), introduced for rapid MR imaging by Michael Lustig, David Donoho, and John M. Pauly in 2007[18](https://doi.org/10.1002/mrm.21391), reduces ¹H MRSI acquisition time by up to 80% or more with negligible loss of clinically relevant information[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/); subsequent developments include compressed-sensing low-rank reconstruction at 7 T (Antoine Klauser and colleagues, 2021)[19](https://doi.org/10.1016/j.jmr.2021.107048) and whole-brain 3D compressed-sensing FID-MRSI (Antoine Klauser and colleagues, 2021).[20](https://doi.org/10.1002/nbm.4615)
## Applications
Brain tumors are the best-established use. Short-TE MRS gives approximately 90% accuracy for pairwise comparisons of the main adult tumor types ([meningiomas](https://www.edgepedia.org/meningioma), low-grade glioma, glioblastoma multiforme, metastases), except glioblastoma versus metastasis at 78%.[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531) Adding MRS to MRI raises the area under the ROC curve for low-grade tumors from 0.81 to 0.93[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531), and MRS (AUC 0.90) outperforms contrast-enhanced [T1-weighted MRI](https://www.edgepedia.org/t1-weighted-mri) (AUC 0.65) for low- versus high-grade grading.[21](https://link.springer.com/article/10.1186/s13244-019-0771-1) Recent whole-brain J-resolved MRSI found, in glioblastoma, elevated choline (45.7%), lactate (1573.2%), and glutamine (79.9%) with decreased NAA (58.2%) in enhancing tumor versus normal region, and in multiple sclerosis, increased lactate (237.0%) and reduced mI/NAA (27.9%) in active versus chronic lesions.[22](https://www.nature.com/articles/s41551-025-01418-4) In prostate cancer, the (choline+creatine)/citrate ratio serves as a biomarker[2](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/), but MRS was dropped from a later version of a structured prostate multiparametric MRI reporting system because it was thought difficult to apply routinely.[23](https://www.nature.com/articles/s44303-023-00004-0.pdf) No published review establishes diagnostic performance for epilepsy localization or hepatic steatosis.
## Limitations and alternatives
MRS is a low-sensitivity method with long acquisitions and several failure modes. Poor \( B_{0} \) homogeneity at 3 T broadens linewidths, whole-brain 3D echo-planar MRSI cannot achieve homogeneous \( B_{0} \) across all regions with second-order shim coils, and voxels near the scalp are contaminated by spurious lipid signals.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/) Small lesion size or susceptibility artifacts near the lesion degrade the analysis; a good-quality spectrum at 1.5 T provides more reliable information than a poor-quality one at 3.0 T.[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531) Broader obstacles include lack of standardization in acquisition and post-processing, voxel placement, and motion sensitivity.[21](https://link.springer.com/article/10.1186/s13244-019-0771-1) At 7 T, small clinical series using sLASER (TR 5000 ms, TE 26–40 ms, 64 averages, VAPOR suppression) are accumulating, but moving 7 T MRS into routine practice is stated to require larger clinical studies, imaging databases, and AI-based predictive models.[15](https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2026.1746678/full) Against alternatives, MRS discriminates metastases from CNS lymphoma/glioblastoma with AUC 0.96, essentially equal to contrast-enhanced perfusion MRI (0.97)[21](https://link.springer.com/article/10.1186/s13244-019-0771-1), while perfusion imaging achieves 72% sensitivity and 92% specificity for tumor versus nonneoplastic lesions[6](https://pubs.rsna.org/doi/10.1148/radiol.13130531); the tCho/NAA ratio distinguishes recurrent glioma from radiation necrosis but is inferior to perfusion MRI for that discrimination.[23](https://www.nature.com/articles/s44303-023-00004-0.pdf) Hyperpolarized ¹³C imaging via dissolution dynamic nuclear polarization enhances ¹³C detection more than 10,000-fold, but the polarization lifetime of [1-¹³C]pyruvate is about 20–30 s, so imaging must finish within 2–3 min of dissolution.[23](https://www.nature.com/articles/s44303-023-00004-0.pdf)
## References
1. [Localized high-resolution proton NMR spectroscopy using stimulated echoes: Initial applications to human brain in vivo](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910090110)
2. [Compressive Sensing Could Accelerate 1H MR Metabolic Imaging in the Clinic](https://pmc.ncbi.nlm.nih.gov/articles/PMC3285227/)
3. [In vivo magnetic resonance spectroscopy: basic methodology and clinical applications (European Biophysics Journal, 2010)](https://link.springer.com/article/10.1007/s00249-009-0517-y)
4. [Magnetic resonance spectroscopy of the brain: a review of physical principles and technical methods (Rev Neurosci)](https://www.degruyterbrill.com/document/doi/10.1515/revneuro-2015-0010/html?lang=en)
5. [A Methodological Consensus on Clinical Proton MR Spectroscopy of the Brain: Review and Recommendations (Wilson et al., Magn Reson Med 2019)](https://pmc.ncbi.nlm.nih.gov/articles/PMC7179569/)
6. [Clinical Proton MR Spectroscopy in Central Nervous System Disorders](https://pubs.rsna.org/doi/10.1148/radiol.13130531)
7. [Estimation of metabolite concentrations from localized in vivo proton NMR spectra (LCModel)](https://onlinelibrary.wiley.com/doi/10.1002/mrm.1910300604)
8. [MR Spectroscopy: The Physical Basis and Acquisition Strategies (AAPM teaching material)](https://www.aapm.org/meetings/amos2/pdf/49-14586-98296-721.pdf)
9. [D. I. Hoult and colleagues (1974). Observation of tissue metabolites using 31P nuclear magnetic resonance. Nature.](https://doi.org/10.1038/252285a0)
10. [R. E. Gordon and colleagues (1980). Localization of metabolites in animals using 31P topical magnetic resonance. Nature.](https://doi.org/10.1038/287736a0)
11. [Joseph J. H. Ackerman and colleagues (1980). Mapping of metabolites in whole animals by 31P NMR using surface coils. Nature.](https://doi.org/10.1038/283167a0)
12. [P A Bottomley and colleagues (1985). In vivo solvent-suppressed localized hydrogen nuclear magnetic resonance spectroscopy: a window to metabolism?. Proceedings of the National Academy of Sciences.](https://doi.org/10.1073/pnas.82.7.2148)
13. [Localized proton spectroscopy using stimulated echoes (Journal of Magnetic Resonance (1969), 1987)](https://doi.org/10.1016/0022-2364%2887%2990154-5)
14. [T R Brown, B M Kincaid, K Ugurbil (1982). NMR chemical shift imaging in three dimensions.. Proceedings of the National Academy of Sciences.](https://doi.org/10.1073/pnas.79.11.3523)
15. [Clinical application of 1H MRS in the human brain at 7T](https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2026.1746678/full)
16. [Short Echo-Time Spiral MRSI Versus Single-Voxel Spectroscopy](https://www.ovid.com/journals/mrim/fulltext/10.1002/mrm.70463~short-echo-time-spiral-mrsi-versus-single-voxel-spectroscopy)
17. [Double DANTE-PRESS: simultaneous in vivo quantification of glutathione and glutamate at 7 Tesla](http://onlinelibrary.wiley.com/doi/10.1002/nbm.70385)
18. [Michael Lustig, David Donoho, John M. Pauly (2007). Sparse MRI: The application of compressed sensing for rapid MR imaging. Magnetic Resonance in Medicine.](https://doi.org/10.1002/mrm.21391)
19. [Antoine Klauser and colleagues (2021). Achieving high-resolution 1H-MRSI of the human brain with compressed-sensing and low-rank reconstruction at 7 Tesla. Journal of Magnetic Resonance.](https://doi.org/10.1016/j.jmr.2021.107048)
20. [Antoine Klauser and colleagues (2021). Whole‐brain high‐resolution metabolite mapping with 3D compressed‐sensing SENSE low‐rank 1 H FID‐MRSI. NMR in Biomedicine.](https://doi.org/10.1002/nbm.4615)
21. [Diagnostic value of alternative techniques to gadolinium-based contrast agents in MR neuroimaging, a comprehensive overview](https://link.springer.com/article/10.1186/s13244-019-0771-1)
22. [Ultrafast J-resolved magnetic resonance spectroscopic imaging for high-resolution metabolic brain imaging](https://www.nature.com/articles/s41551-025-01418-4)
23. [MRS-based metabolic imaging alternatives (hyperpolarized 13C and 2H MRSI) review](https://www.nature.com/articles/s44303-023-00004-0.pdf)
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*Topic: Encyclopedia › Life and health › Human health and medicine › Clinical assessment and procedures › Medical imaging and radiography › Magnetic resonance imaging techniques*
*Initially written Sep 29, 2026 · Edited: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license