Brain (Head) MRS - CAM 766

Magnetic resonance spectroscopy (MRS) is a noninvasive imaging technique that determines the concentration of brain metabolites, such as N-acetylaspartate, choline, creatine, and lactate, within the body tissue examined. Radiofrequency waves are translated into biochemical composition of the scanned tissue; the resulting metabolic profile is useful in identifying brain tumors, e.g., differentiating neoplastic and non-neoplastic brain lesions. In selected cases, MRS may be a valuable supplement to MRI. It is sensitive, but nonspecific. This modality should be considered as an adjunct to conventional imaging rather than replacement for histopathological evaluation.

In terms of brain tumor evaluation and classification, carefully designed multi-center trials complying with criteria of evidence-based medicine have not yet been completed (Horská, 2010).

Tumor Recurrence vs. Radiation Necrosis Differentiation between recurrent brain tumors and treatment related injury, e.g., radiation necrosis, is difficult using conventional MRI. The typical appearance of radiation necrosis is similar to that of recurrent brain tumors. MRS is a quantitative approach, measuring various brain metabolic markers, to help in the differentiation of recurrent tumors and radiation necrosis. This differentiation is important as additional radiation can benefit recurrent disease but can be detrimental to radiation necrosis. MRS may help in determining treatment options and in preventing unnecessary surgery. In addition, a tumor recurrence diagnosed by MRS allows the surgeon to begin treatment early instead of having to wait for symptoms of recurrence or biopsy confirmation (Barajas, 2009; Chuang, 2016; Smith, 2009). However, no consensus exists regarding the value of this in clinical decision making, and no approach has yet been validated to be sufficiently accurate (Chuang, 2016; Sundgren, 2009; Walker, 2014).

Glioma – MRS has been proposed for pre-operative grading of gliomas and differentiating high-grade gliomas (HGGs) from low-grade gliomas. It has been found to have moderate diagnostic value and should be combined with other advanced imaging techniques to improve accuracy. Currently, the data is limited; more research is needed for a definite conclusion for the utility of MRS for this indication. Therefore, it remains experimental/investigational (Abrigo, 2018; Wang, 2016).

MRS in other diseases A role for MRS has been suggested in the management of neurodegenerative disease, epilepsy, and stroke. However, to better define this role, it will be necessary to standardize the MRS methodology, as well as the collection, analysis, and interpretation of data so it can be consistently translated to the applicable clinical settings. Currently, these potential applications remain experimental/investigational (Oz, 2014).

BRAIN MRS is considered MEDICALLY NECESSARY for the following indications:

  • For the evaluation of a recurrent or residual brain tumor from post-treatment changes e.g., radiation necrosis.
  • For further evaluation a brain lesion to distinguish a brain tumor from other non-tumor diagnoses (e.g. abscess or other infectious or inflammatory process).

All other uses of this technology are investigational and/or unproven and therefore considered NOT MEDICALLY NECESSARY.


  1. Abrigo JM, Fountain DM, Provenzale JM, et al. Magnetic resonance perfusion for differentiating low-grade from high-grade gliomas at first presentation. Cochrane Database Syst Rev. 2018 Jan 22; 1(1):CD011551.
  2. Alam MS, Sajjad Z, Hafeez S, et al. Magnetic resonance spectroscopy in focal brain lesions. J Pak Med Assoc. 2011 Jun; 61(6):540-3.
  3. American College of Radiology (ACR). ACR–ASNR–SPR practice parameter for the performance and interpretation of magnetic resonance spectroscopy of the central nervous system. Revised 2019.  
  4. Barajas RF, Chang JS, Sneed PK, et al. Distinguishing recurrent intra-axial metastatic tumor from radiation necrosis following gamma knife radiosurgery using dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging. AJNR Am J Neuroradiol. 2009; 30:367-372. doi: 10.3174/ajnr.A1362.
  5. Chuang MT, Liu YS, Tsai YS, et al. Differentiating radiation-induced necrosis from recurrent brain tumor using MR perfusion and spectroscopy: A meta-analysis. PLoS One. 2016 Jan 7; 11(1):e0141438.
  6. Hellström J, Romanos Zapata R, Libard S, et al. The value of magnetic resonance spectroscopy as a supplement to MRI of the brain in a clinical setting. PLoS One. 2018 Nov 15; 13(11):e0207336.
  7. Horská A, Barker PB. Imaging of brain tumors: MR spectroscopy and metabolic imaging. Neuroimaging Clin N Am. 2010; 20(3):293–310.
  8. Lin A, Ross BD, Harris K, et al. Efficacy of proton magnetic resonance spectroscopy in neurological diagnosis and neurotherapeutic decision making. NeuroRx. 2005; 2(2):197-214.
  9. Majós C, Aguilera C, Alonso J, et al. Proton MR spectroscopy improves discrimination between tumor and pseudotumoral lesion in solid brain masses. AJNR Am J Neuroradiol. 2009 Mar; 30(3):544-51. Epub 2008 Dec 18.
  10. Mishra AM, Gupta RK, Jaggi RS, et al. Role of diffusion-weighted imaging and in vivo proton magnetic resonance spectroscopy in the differential diagnosis of ring-enhancing intracranial cystic mass lesions. J Comput Assist Tomogr. 2004 Jul-Aug; 28(4):540-7.
  11. Oz G, Alger JR, Peter B, et al. Clinical proton MR spectroscopy in central nervous system disorders. Radiology. March 2014; 270(3):658-679.
  12. Smith EA, Carlos RC, Junck LR, et al. Developing a clinical decision model: MR spectroscopy to differentiate between recurrent tumor and radiation change in patients with new contrast-enhancing lesions. Am J Roentgenol. 2009; 192(2):W45-52. doi: 10.2214/AJR.07.3934.
  13. Sundgren PC. MR spectroscopy in radiation injury. AJNR Am J Neuroradiol. 2009; 30:1469-1476.
  14. Walker AJ, Ruzevick J, Malayeri AA, et al. Postradiation imaging changes in the CNS: How can we differentiate between treatment effect and disease progression? Future Oncol. 2014; 10(7):1277–1297.
  15. Wang Q, Zhang H, Zhang J, et al. The diagnostic performance of magnetic resonance spectroscopy in differentiating high-from low-grade gliomas: A systematic review and meta-analysis. Eur Radiol. 2016; 26(8):2670-2684.  

Coding Section 

Codes Number Description
CPT 76390 Magnetic resonance spectroscopy

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, Blue Cross and Blue Shield Association technology assessment program (TEC) and other non-affiliated technology evaluation centers, reference to federal regulations, other plan medical policies and accredited national guidelines.

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History From 2014 Forward     


Annual review, no change to policy intent. Updating description and references. 


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Annual review.  Updated rationale and references. Added benefit application. No change to policy intent.

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