Molecular characterization of musculoskeletal tumors by proton MR spectroscopy

Although conventional magnetic resonance (MR) imaging with T1, T2, and gadolinium enhancement is the primary modality used for characterizing musculoskeletal lesions, its specificity for distinguishing malignancy from nonmalignant tissue remains low. Proton MR spectroscopy (MRS) is a new approach to the evaluation of musculoskeletal lesions that offers a method of metabolic imaging with MR. With proton MRS, a footprint of metabolite concentration in a region of interest can be obtained and markers for malignancy can be detected, such as elevated concentrations of the metabolite choline. Proton MRS is one of the most promising noninvasive techniques available for molecular identification of malignant tumor markers. However, the role of MRS in the assessment of musculoskeletal tumors remains in its infancy. In this article, we discuss the technical aspects of performing proton MRS, including differences between single voxel and multivoxel technique and its advantages and limitations. We demonstrate its potential utility in the evaluation of musculoskeletal lesions through a series of examples.