MR spectroscopy (MRS)

MR spectroscopy (MRS) measures the chemistry of your tissues non-invasively, on a standard MRI scanner. It reads the slight frequency shifts in the MR signal to quantify specific metabolites, usually from one small box (voxel) or a grid of them. In the brain, 1H-MRS measures things like NAA (a marker of healthy neurons), choline, creatine, lactate, myo-inositol, glutamate/glutamine, and glutathione. Those help with grading tumors, and studying mitochondrial disease, multiple sclerosis, and neurodegeneration. In the liver, a related technique (MR-PDFF) is the most accurate non-invasive measure of liver fat. It has become the imaging endpoint of choice in fatty-liver (MASLD/MASH) trials, matching biopsy grades well. MRS uses no radiation. Its limits: long scan times, sensitivity to motion and field unevenness, modest spatial detail, and the need for specialized processing.

Last reviewed: June 22, 2026

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