CurrentBlue Cross Blue Shield - KansasPolicy N/A

Magnetic Resonance Spectroscopy (MRS) — Medical Policy

This medical policy governs the use and coverage determination of proton magnetic resonance spectroscopy as an adjunct to MRI for brain tumors and various non‑cancer indications for members of Blue Cross and Blue Shield of Kansas.

Policy Summary

PayerBlue Cross Blue Shield - Kansas

PolicyMagnetic Resonance Spectroscopy (MRS) — Medical Policy

Policy CodePolicy N/A

Change TypeNo material changes

Effective DateJuly 16, 2009

Next Review DateN/A

Key ActionVerify member benefits with Blue Cross and Blue Shield of Kansas Customer Service because MRS is considered experimental/investigational and coverage depends on the member's contract.

SourceLink

POLICY UPDATE CHANGES

No material clinical or coverage changes in this revision.

Dec 3, 2024Latest Review Date

No RCTsRCTs identified

95% / 91%2HG MRS sensitivity/specificity

15–30 minTypical added scan time

1–8 cm3Typical voxel volume

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Coverage Criteria and Rationale

Overall coverage stance and clinical question

Policy position and intended clinical question

Policy stance: Magnetic resonance spectroscopy is considered experimental / investigational.

Refer to member contract for coverage determinations.

Evidence-based coverage considerations

Evidence summary and implications for medical necessity

Diagnostic performance for general brain tumor detection/grading: Meta-analysis (Wang et al 2014) found pooled sensitivity 80.1% and specificity 78.5% for MRS detecting or grading brain tumors; overall AUC 0.78.

Moderate diagnostic accuracy; heterogeneity in studies.

Adjunctive value to MRI: Some studies report improved diagnostic accuracy when MRS is added to MRI (e.g., pediatric and select series), but results are inconsistent and not uniformly statistically significant (Hellstrom et al 2018 showed no significant overall difference).

Benefit varies by study and indication; not uniformly additive.

Pediatric brain tumor diagnosis: Prospective pediatric studies (Manias et al 2019; Shiroishi et al 2015) reported improved correct diagnosis rates when MRI and MRS were combined (examples: MRI 63%-71% vs MRI+MRS 77%-87%).

Proportion analyzable spectra and modest sample sizes limit generalizability.

IDH-mutant glioma detection: Systematic reviews/meta-analyses (Suh et al 2018; Bhandari et al 2021) report high pooled sensitivity and specificity for 2HG MRS to detect IDH mutations (e.g., pooled sensitivity 95% and specificity 91% reported by Suh et al).

Techniques and cut-offs vary; results are promising for noninvasive IDH status assessment but require standardization.

Clinical utility evidence: No randomized controlled trials comparing patient management with versus without MRS were identified; observational studies report management changes in select cases (e.g., biopsy avoidance), but direct evidence of improved health outcomes is lacking.

Chain of evidence cannot be completed when clinical validity is insufficient.

Overall conclusion for coverage: Because clinical validity is not fully established across indications and no RCTs of clinical utility were identified, definitive clinical utility is unproven based on available evidence.

Policy authors conclude insufficient evidence to construct a chain of evidence for utility.

Brain Tumors

Summary statements on evidence and applicability for indications covered in this excerpt.

Brain Tumors - Evidence Summary: Systematic reviews and nonrandomized studies assess detection, characterization, grading, prognosis, and differentiation of recurrence versus radiation necrosis. Most studies are small, retrospective, and use varying metabolite ratios; the largest prospective pediatric study found improved correct diagnosis when combining MRS with MRI. Prospective studies are needed to better define spectra, diagnostic accuracy, and effects on health outcomes.

See systematic reviews and section summary.

Direct evidence: No randomized controlled trials were identified demonstrating that use of MRS improves health outcomes for brain tumor management; some observational studies reported management changes such as biopsy avoidance in select pediatric cases.

Direct RCT evidence absent.

Chain of evidence consideration: Because clinical validity has not been definitively established for many brain tumor applications, an indirect chain of evidence to clinical utility cannot be completed in these sections.

Limits inference of clinical utility.

Breast Cancer

Evidence and intended use for breast cancer evaluation using MRS.

Breast Cancer - Diagnostic Performance: Systematic reviews/meta-analyses report pooled MRS sensitivity approximately 73%–85% and specificity approximately 85%–88% for differentiating benign versus malignant breast lesions, with significant heterogeneity and potential publication bias; DWI may have similar or better performance in pooled analyses.

Interpret with caution due to heterogeneity and risk of bias.

Breast Cancer - Treatment Response: Small prospective studies (e.g., Bayoumi et al 2019) report that combined MRI and MRS can improve specificity and overall diagnostic accuracy for confirming pathological complete response after neoadjuvant chemotherapy (reported combined accuracy 91.5%), though study details and generalizability are limited.

Patient selection and small sample size limit conclusions.

Breast Cancer - Clinical validity/utility: Clinical validity across settings is not definitively established and no RCTs of clinical utility were identified; therefore the chain of evidence to improved health outcomes is incomplete and clinical utility remains uncertain.

Prostate Cancer

Prostate cancer — intended use and population in this excerpt.

Prostate Cancer - Scope: MRS has been evaluated for diagnosis, recurrence assessment, and localization to guide targeted biopsy and treatment planning in individuals with elevated PSA and prior negative biopsy or suspected prostate cancer.

Several RCTs/controlled trials and nonrandomized studies exist but overall evidence is heterogeneous.

Available trial evidence: Randomized trials (e.g., Sciarra et al 2010; Panebianco et al 2010) compared MRS ± DCE-MRI–guided targeted biopsy with random biopsy and reported higher cancer detection rates when imaging-guided biopsy was used; however, the impact on clinically meaningful patient outcomes and the potential for overdiagnosis/overtreatment remain uncertain.

Clinical outcome benefit from increased detection has not been demonstrated.

Prostate - Coverage implication: Cumulative evidence is uncertain; comparative accuracy versus alternative imaging strategies and effect on management and health outcomes are not established, limiting support for routine coverage.

Policy states evidence remains insufficient to conclude clinical utility.

Overall coverage rationale

Summary of evidence linking clinical validity to clinical utility

Clinical validity not established: Clinical validity of MRS for many indications (including prostate cancer and dementia) has not been established sufficiently to support inference of clinical utility; meta-analyses show variable sensitivity and specificity and limitations in study quality and applicability.

Supported by systematic reviews and section summaries.

No direct evidence of improved health outcomes: No randomized controlled trials were identified that demonstrate MRS use improves patient health outcomes compared with management without the test for most indications reviewed.

Direct evidence absent or limited per document.

Uncertain impact on management: The impact of MRS on clinical management and downstream health outcomes is uncertain; data comparing MRS with alternative imaging strategies are limited.

Policy concludes cumulative evidence remains uncertain.

Coverage stance by clinical area

Covered when ALL of the following are met

Prostate cancer section conclusion: Cumulative evidence for routine clinical use of MRS in prostate cancer is uncertain; impact on management and outcomes is unknown.

Evidence insufficient to consider medically necessary for routine use.

Dementia section conclusion: MRS has not demonstrated clinical validity or utility for dementia; no RCTs and insufficient diagnostic comparators exist.

Role limited to research settings per section summary.

Liver disease section note: MRS has been evaluated against liver biopsy and other imaging modalities for hepatic steatosis but available evidence does not support clinical utility.

DGE-MRI may outperform MRS for higher degrees of steatosis.

Liver Disease — Not Supported

Summary conclusions for hepatic steatosis:

Liver disease - coverage conclusion: Available evidence does not support the clinical utility of MRS for assessment of hepatic steatosis; in a prospective study of potential living liver donors DGE-MRI outperformed MRS for detecting ≥30% steatosis.

MRS not supported for routine assessment of hepatic steatosis.

Multiple Sclerosis — Insufficient Evidence

Summary conclusions for multiple sclerosis:

Multiple sclerosis - evidence status: Evidence consists of nonrandomized cross-sectional and longitudinal studies showing associations between MRS-derived neurometabolites and some clinical measures, but effect sizes are small and no RCT evidence demonstrates that MRS-guided management improves patient outcomes; therefore clinical utility is unproven.

Larger prospective studies with serial measures and outcome correlations are needed.

Psychiatric Disorders — Not supported outside research

Summary coverage stance based on evidence in this section:

Psychiatric disorders coverage: MRS is not supported for clinical use outside of research settings for psychiatric disorders due to inconsistent diagnostic validity and no evidence that MRS predicts treatment response or improves health outcomes.

Policy recommends research use only for psychiatric indications.

Other Indications — Insufficient evidence

Evidence considerations for neurologic and other indications:

Neurologic/other indications: MRS has been evaluated for multiple other indications (neonatal encephalopathy, traumatic brain injury, carotid plaque, systemic lupus, pediatric seizures, and others) but current evidence is insufficient to establish clinical validity and utility for routine clinical use.

Additional larger and prospective studies with appropriate reference standards are needed.

Magnetic resonance spectroscopy (MRS) is designated as experimental / investigational by this policy. Coverage for MRS is determined by the member's contract benefits at the time of service; if the contract does not provide coverage for investigational services, MRS will be excluded.

The policy notes that no randomized controlled trials (RCTs) were identified demonstrating that use of MRS improves patient health outcomes compared with management without the test. When RCT evidence is absent, the policy relies on a chain of evidence approach: indirect evidence of clinical utility requires established clinical validity; if clinical validity is not demonstrated, inferences about clinical utility cannot be made.

Because the clinical validity of MRS has not been established for many indications reviewed in this policy, a chain of evidence cannot be constructed. This limitation reduces the ability to infer that MRS use changes management in ways that improve health outcomes and therefore constrains coverage conclusions.

For prostate cancer, the document states that while multiple studies have evaluated MRS for diagnosis, localization, and monitoring, the cumulative evidence remains uncertain. Comparative data with alternative imaging strategies are limited and the impact on clinical management and health outcomes is unknown, so routine clinical coverage is not supported based on the evidence presented.

The policy concludes that use of MRS for identifying or monitoring cognitive impairment and dementia is limited to research settings. There are no clear diagnostic criteria established with MRS, insufficient data on diagnostic comparators, and the effect on management or outcomes is unknown.

Available evidence does not support the utility of MRS for assessment of hepatic steatosis. Comparative imaging studies and guideline summaries referenced in the review indicate MRS is not demonstrated to provide clinical utility for liver fat quantification relative to established comparators.

For psychiatric disorders, the policy states that current evidence does not support routine clinical use of MRS outside of research. Studies show inconsistent diagnostic validity, preliminary failure to predict treatment response, and an unknown impact on health outcomes.

Practice guidance from professional bodies notes that MRS of the head without IV contrast is usually not appropriate for dementia, head trauma, movement disorders, and certain neurodegenerative conditions. NICE guidance also advises limited use of MRS and recommends it only when findings from standard imaging are unclear and early identification would be clinically useful.

Within the cited document segments there are no additional explicit coverage exclusions listed beyond the policy designation and condition-specific summaries; providers are directed to consult member contract language for coverage determinations.

The policy emphasizes that clinical utility is not established for indications lacking adequate clinical validity and direct outcome evidence. Without demonstrated test performance and outcome benefit, MRS cannot be assumed to inform management decisions that improve net health outcomes.

Across multiple clinical areas reviewed, the document finds no RCTs identified that show MRS use leads to improved health outcomes. The absence of randomized intervention studies is highlighted as a major evidence gap for establishing clinical utility.

Because diagnostic performance (clinical validity) is insufficient or inconsistent for several indications, the policy states that the clinical utility of MRS is uncertain. This uncertainty underpins the policy's noncoverage stance for routine use in those areas.

The document specifically notes that MRS is considered not medically necessary for routine clinical management of prostate cancer and dementia due to insufficient evidence of clinical validity and lack of demonstrated impact on health outcomes.

MRS is described as not medically necessary for assessment of hepatic steatosis and, in the case of multiple sclerosis, as lacking RCT evidence to support routine use; thus these indications are not supported by the available evidence.

The policy states MRS for psychiatric disorders is not medically necessary for routine clinical diagnosis or prediction of treatment response, and its role is restricted to research settings given inconsistent validity and unknown outcome impact.

The ACR/ASNR/SPR practice parameters and NICE recommendations are reiterated: MRS has a limited set of appropriate uses and is usually not appropriate for several head indications when performed without IV contrast; guideline statements limit routine clinical application.

In the document excerpts provided there are no additional explicit statements labeling other specific indications as 'not medically necessary'; the policy focuses on the investigational designation and condition-level summaries to guide coverage decisions.

Clinical Indications Evaluated and Coverage Position by Indication

Clinical indications evaluated — top-level node

Top-level list of clinical indications evaluated in the evidence review

Indications evaluated in evidence review: Differentiate malignant from nonmalignant brain tumors; evaluate tumor grade; distinguish metastatic from primary brain tumors; detect tumor recurrence versus radiation necrosis; pediatric tumor typing; noninvasive IDH mutation assessment (2HG MRS); treatment response monitoring; and additional noncancer applications including breast lesion characterization, prostate cancer localization for biopsy, hepatic steatosis assessment, dementia/cognitive impairment evaluation, multiple sclerosis, psychiatric disorders, neonatal encephalopathy, and other investigational uses.

Evidence review focused primarily on brain tumors; other applications reviewed with varying evidence strength.

Adjunctive use of MRS in brain imaging for tumor detection, grading, recurrence differentiation, pediatric tumor typing, IDH mutation status, and treatment response monitoring.

Adjunctive use of MRS in brain imaging for tumor-related questions

Brain tumor adjunct indications: Adjunct to MRI for detection and grading of brain tumors; differentiation of recurrence from radiation necrosis; pediatric tumor typing; noninvasive determination of IDH mutation status using 2HG MRS; and monitoring treatment response.

Performance varies by indication and technique; prospective validation needed.

Adjunct to MRI for evaluation of brain tumors, breast lesions, and prostate cancer.

Adjunct to MRI for oncologic evaluations beyond the brain

Adjunct to MRI — multi-site indications: MRS as an adjunct to MRI has been evaluated for characterization of brain tumors, differentiation of benign versus malignant breast lesions, assessment of treatment response after neoadjuvant chemotherapy in breast cancer, and for evaluation/localization of prostate cancer to guide targeted biopsy and planning.

Evidence strength and applicability vary by clinical area; chain of evidence often incomplete.

Evaluation and localization of suspected prostate cancer to guide targeted biopsy

Clinical scenarios for prostate cancer evaluation where MRS has been evaluated

Prostate targeted biopsy localization: MRS combined with DCE-MRI has been evaluated to localize suspected prostate cancer in patients with elevated PSA and prior negative biopsy to guide targeted biopsy; randomized and prospective studies reported higher detection rates with imaging-guided biopsy strategies.

Impact on long-term clinical outcomes and potential overdiagnosis is uncertain.

Prostate cancer evaluation

Prostate cancer evaluation — evidence summary

Prostate cancer evaluation: MRS has potential applications for diagnosis, recurrence assessment, and localization for biopsy and treatment planning; however, cumulative evidence is heterogeneous and impact on patient outcomes is not established.

Policy notes uncertainty and need for further comparative and outcome studies.

Dementia / cognitive impairment evaluation

Dementia / cognitive impairment evaluation — evidence context and limitations

Dementia MRS indication: MRS has been studied to identify metabolite pattern changes (e.g., decreased NAA, altered NAA/Cr and NAA/mI ratios; increased myo-inositol) in cognitive impairment and dementia, but clinical validity and diagnostic criteria are not established and no RCTs demonstrate clinical utility.

Role currently limited to research settings.

Liver disease evaluation

Liver disease evaluation — comparator and findings

Liver disease evaluation: MRS has been evaluated as a noninvasive alternative to liver biopsy and compared with other imaging methods (e.g., DGE-MRI); prospective data indicate DGE-MRI may be more accurate than MRS for higher degrees of steatosis (≥30%).

Evidence does not support routine use of MRS for hepatic steatosis assessment.

Hepatic steatosis — not supported

Hepatic steatosis — evidence and coverage conclusion

Hepatic steatosis indication: MRS has been evaluated for assessment of hepatic steatosis but current evidence does not support its clinical utility as an alternative to liver biopsy or more accurate imaging modalities for clinically relevant degrees of steatosis.

Policy concludes MRS is not supported for hepatic steatosis.

Multiple sclerosis — investigational/insufficient evidence

Multiple sclerosis — evidence limitations and implications

Multiple sclerosis indication: MRS measures neurometabolites associated with MS and has shown some correlations with clinical measures in cross-sectional and longitudinal studies, but effect sizes are small and no RCTs demonstrate that MRS-guided management improves outcomes; therefore MRS for MS is investigational/insufficient evidence for routine clinical use.

Larger and longer prospective studies are needed.

Investigational/Research indications for MRS (various neurologic and pediatric uses)

Investigational and research indications summarized

Research/Investigational Indications: MRS has investigational applications including tracking disease in systemic lupus, assessing carotid plaque, identifying biomarkers in traumatic brain injury, predicting neurodevelopmental outcomes after neonatal encephalopathy, and pediatric seizure evaluation; additional evidence is required before routine clinical coverage.

Listed uses are considered investigational pending further study.

Psychiatric disorders

Psychiatric disorders — evidence summary

Psychiatric disorders: MRS has been evaluated in mood disorders, bipolar disorder, schizophrenia, and other psychiatric conditions, but diagnostic validity is inconsistent and studies have not demonstrated that MRS predicts treatment response or improves clinical outcomes; use is investigational and limited to research settings.

Policy advises against routine clinical use for psychiatric indications.

Advanced imaging adjunct when standard imaging is inconclusive for tumor characterization or recurrence assessment

Guideline-based situational use when standard imaging is inconclusive

Advanced imaging adjunct: Guidelines (ACR/ASNR/SPR; NCCN; NICE) identify MRS as one modality to consider when conventional MRI/CT is inadequate for specific questions (for example, distinguishing radiation necrosis from recurrence, assessing potential high-grade transformation, aiding tumor grading, or targeting biopsy), with limitations near vessels, air spaces, or bone and added scan time requirements.

Guidelines note MRS may be ‘‘usually not appropriate’’ in some head imaging scenarios without IV contrast (e.g., dementia, head trauma).

Clinical indications cited in the literature for MRS (see supporting references).

Clinical areas cited in the literature for MRS

Literature-cited clinical indications: Published literature and reviews list MRS applications in breast lesions, prostate cancer localization, Alzheimer disease and mild cognitive impairment, hepatic steatosis, multiple sclerosis, psychiatric disorders, neonatal hypoxic-ischemic encephalopathy, seizures, traumatic brain injury, and various pediatric and neurologic conditions.

References and systematic reviews cited in the bibliography support this aggregated list.

Procedure and Regulatory Codes

Regulatory identifiersmixed

FDA product code LNH

FDA product code for proton MRS software/hardware cleared via 510(k)

Included procedure codesCPT

76390

Magnetic resonance spectroscopy

Typical MRS voxel volume

Typical voxel volume1 to 8 cm^3

Voxel shapeCube or rectangular prism (3-dimensional volume × pixel)

Acquisition impactAdds approximately 15–30 minutes of scanner time

Authorization, Documentation, and Billing Guidance

Prior Authorization

Benefit Verification and Coverage Determination

State and Federal mandates and member contract provisions take precedence over this Medical Policy. Providers must verify member benefits and eligibility prior to ordering Magnetic Resonance Spectroscopy (MRS). For benefit verification or coverage questions, contact Blue Cross and Blue Shield of Kansas Customer Service or your professional/institutional relations representative.

Benefit verification required — contact Blue Cross and Blue Shield of Kansas Customer Service.
Coverage depends on member contract language and any applicable state or federal mandates.
If questions about coverage, contact Blue Cross and Blue Shield of Kansas customer service or professional/institutional relations.

Denial Risk

Denial Risk — Experimental / Investigational

MRS is considered experimental/investigational in this policy. Because clinical utility is not established for multiple indications (brain tumors, prostate cancer, dementia, liver disease, multiple sclerosis, psychiatric disorders), use of MRS may be denied when it is not supported by the member's contract or when clinical utility is unproven.

MRS is listed as experimental/investigational in this policy.
Lack of randomized controlled trials and uncertain impact on health outcomes are noted across indications.

Prior Authorization

Prior Authorization and Authorization Inquiries

No specific prior authorization rule is set within this document. Providers should contact Blue Cross and Blue Shield of Kansas to determine whether prior authorization is required for a given member and service date.

Prior authorization not specified in this policy excerpt — check member contract and contact BCBSKS for authorization requirements.
Coverage and coding listed are informational; actual coverage is determined by performance per policy and member benefits.

Documentation Required

Documentation Expectations

Document clinical rationale and supporting literature when submitting requests or appeals for MRS. Include the clinical question, patient population, indication, and relevant study data that support medical necessity. Retain copies of member benefit verification and any BCBSKS guidance provided.

Provide study-level evidence and documentation of how MRS results will change management.
Identify population and clinical question in submitted documentation.

Billing Rule

Billing and Coding Note

Coding listed (e.g., CPT 76390 for magnetic resonance spectroscopy) is informational. Inclusion on this list does not guarantee coverage or reimbursement — determine coverage by reference to the Policy section and member contract.

CPT/HCPCS 76390 = Magnetic resonance spectroscopy (informational only).
Inclusion of a code does not imply coverage; coverage is per the Policy section and member contract.

Prior Authorization Notes

Prior Authorization

MRS — Coverage determination requires checking member contract; policy labels MRS as experimental/investigational

The policy states that coverage determination requires checking the member's contract; MRS is designated experimental/investigational and may be excluded unless the contract provides coverage.

Prior Authorization

MRS — Not specified; evidence gaps may prompt pre-authorization requirements

No specific prior-authorization rules are detailed in the excerpts; evidence gaps are noted that may prompt payers to require pre-authorization depending on their processes.

Prior Authorization

MRS — Not specified in this excerpt

The provided excerpts do not include explicit prior-authorization criteria or thresholds for MRS.

Prior Authorization

MRS — No explicit threshold provided; prior authorization guidance not specified

No explicit prior-authorization thresholds or guidance are provided in the excerpted policy sections.

Prior Authorization

MRS — No explicit prior authorization thresholds specified

The document does not specify prior-authorization thresholds for MRS in these chunks.

Prior Authorization

MRS — Requests outside research settings will likely require substantive justification

Requests for MRS outside research settings will likely require substantive justification because randomized controlled trial evidence is lacking and clinical validity is undefined for many indications.

Document intended clinical management changes and supporting evidence when requesting MRS for clinical use.

Note

MRS — Not specified in these chunks; contact payer

These chunks do not provide payer contact specifics; contact BCBSKS customer service as policy suggests.

Contrast Agent Guidance

Billing Rule

CONTRAST RULES — No explicit contrast-agent rules provided in this excerpt

No contrast-agent requirements are provided in the excerpt; consult full policy or payer guidance for contrast administration rules.

Billing Rule

CONTRAST RULES — When MRS used with DCE-MRI; studies often combine modalities

Studies often evaluated MRS in combination with dynamic contrast-enhanced MRI (DCE-MRI); when combined, DCE-MRI and MRS have been used to target biopsy and improve detection in some studies.

Document whether MRS will be performed with DCE-MRI and include justification if billing both procedures.

Billing Rule

CONTRAST RULES — No contrast-specific rules mentioned

No contrast-specific billing rules are mentioned in these chunks of the policy.

Billing Rule

CONTRAST RULES — Head MRS without IV contrast considered usually not appropriate for several neurologic indications per ACR

The ACR guidance cited considers head MRS without IV contrast 'usually not appropriate' for dementia, head trauma, movement disorders, and neurodegenerative diseases; providers should document indication and any contrast-use rationale.

If performing head MRS without IV contrast for these indications, include justification referencing specific clinical circumstances and guideline exceptions.

Not Covered / Experimental Uses

Per the policy position that MRS is experimental/investigational, clinical indications evaluated under this designation are not covered except where the member's contract explicitly provides otherwise. Providers should expect denial risk for requests that lack contract coverage or supporting evidence of clinical utility.

This entry is a duplicate grouping placeholder in the policy; the central coverage stance remains that MRS is experimental/investigational and coverage is determined by member contract.

This entry is a duplicate grouping placeholder in the policy; see the policy statement that MRS is considered experimental/investigational and coverage depends on the member's contract.

This is a duplicate placeholder grouping; the policy's not-covered position for investigational procedures applies to MRS unless the member contract provides coverage.

Duplicate placeholder: MRS is labeled experimental/investigational and may be excluded from coverage per member contract.

Duplicate placeholder: the investigational designation for MRS is the controlling policy statement; check member benefits for coverage.

Duplicate placeholder noting the policy designation; providers should verify member contract benefits to determine coverage status.

Duplicate placeholder summary: MRS is considered experimental/investigational per this policy and coverage is contingent on contract language.

The policy and cited guidelines classify head MRS without IV contrast as usually not appropriate for dementia, head trauma, movement disorders, and neurodegenerative diseases; requests for such uses are therefore unsupported for routine coverage.

Background and Definitions

Magnetic resonance spectroscopy (MRS) is a noninvasive adjunct to MRI that measures tissue chemical concentrations using proton (1‑H) nuclei. Typical MRS evaluates metabolite peaks such as N‑acetylaspartate (NAA), choline (Cho), creatine, myo‑inositol, lipid, and lactate. Acquisition of MRS sequences increases MRI exam time (commonly by 15–30 minutes) and uses voxel volumes typically in the range of 1 to 8 cm³.

Proton MRS — technique using hydrogen (1-H) nuclei; proton MRS implied throughout

TechniqueProton MRS (1‑H) — uses hydrogen nuclei to obtain spectra of brain metabolites

Scope in this reviewAll findings in the evidence review refer to proton MRS unless otherwise indicated

Relationship to MRIPerformed as an adjunct to MRI: MRI image acquired first, then MRS spectra developed at site of interest

N-acetylaspartate (NAA) definition

DefinitionN‑acetylaspartate (NAA) is an amino acid produced by mitochondria, present almost exclusively in neurons and axons in the adult CNS; NAA intensity is a marker of neuronal integrity

Clinical implicationDecreased NAA signal is associated with neuronal loss, structural neuronal damage, and/or reduced neural metabolism

Role in MRSNAA is the most important proton signal when studying central nervous system pathology

Choline (Cho) definition

DefinitionCholine (Cho) arises from choline-containing compounds (eg, phosphocholine, glycerophosphocholine) related to membrane phospholipids

Clinical implicationIncreased Cho is a marker of pathologic membrane proliferation/degradation and is most commonly associated with neoplasms

Other influencesCho levels can also be affected by diet and medication and may increase in acute demyelinating disease

Clinically Valid / Clinically Useful definitions

Clinically valid — definitionA test must detect presence/absence of a condition, risk of developing a condition, or treatment response (beneficial or adverse)

Clinically useful — definitionUse of test results informs management decisions that improve net health outcomes (eg, correct therapy, more effective therapy, or avoidance of unnecessary therapy/testing)

Chain of evidence implicationClinical utility inferences require established clinical validity; without validity a chain of evidence cannot be constructed

2-hydroxyglutarate (2HG) MRS definition

Definition2‑hydroxyglutarate (2HG) MRS: an MRS technique to noninvasively detect tumor 2HG, a biomarker of IDH1/IDH2 mutation status in gliomas

Diagnostic performanceMeta-analysis (Suh et al 2018) reported pooled sensitivity ~95% and specificity ~91% for detecting IDH‑mutant glioma

Potential useMay be used to noninvasively assess IDH mutation status as an alternative to biopsy-based molecular testing, though techniques/cut-offs vary

Clinically Valid definition (repeat)

Clinically valid — conciseA test must detect presence/absence of a condition, risk of developing a condition, or treatment response

ContextClinical validity is a prerequisite for constructing an evidence chain to clinical utility

Evaluation expectationStudies should report accuracy of the marketed version and include suitable reference standards and validation cohorts

Clinically Useful definition (repeat)

Clinically useful — conciseA test is clinically useful if results inform management decisions that improve net health outcomes

Net health outcome examplesImprovement can occur via correct/ more effective therapy or avoidance of unnecessary therapy/testing

Evidence requirementDirect RCT evidence comparing management with versus without the test is preferred to demonstrate clinical utility

MRS definition in prostate context

Definition in prostate contextMagnetic resonance spectroscopy (MRS) is an MRI technique that evaluates tissue metabolites to aid detection and localization of prostate cancer

Common combined modalityStudies often evaluate MRS together with dynamic contrast‑enhanced MRI (DCE‑MRI) and diffusion sequences for targeted biopsy guidance

Population studiedTypically evaluated in patients with elevated PSA and prior negative biopsy to guide targeted biopsy

DCE-MRI definition

DefinitionDynamic contrast‑enhanced MRI (DCE‑MRI) assesses vascular contrast kinetics over time and is frequently combined with MRS in studies

Use caseDCE‑MRI is used with MRS for targeted biopsy guidance and evaluation of lesion vascularity in prostate and other tumor studies

Relation to MRSCombined MRS+DCE approaches have been evaluated to improve detection/localization, but impact on clinical outcomes remains uncertain

MRS metabolite patterns (dementia studies)

Observed patternsDementia studies report decreased NAA and altered metabolite ratios (eg, NAA/Cr, NAA/mI) and increased mI, Cho/Cr, and mI/NAA in affected regions

InterpretationThese metabolite changes are heterogeneous across brain regions and studies; multimarker approaches may be needed

Evidence gapLarge longitudinal studies are needed to clarify biomarker associations and clinical relevance

Clinical utility / chain of evidence definition

Clinical utility definitionClinical utility is demonstrated when test use informs management decisions that improve net health outcomes

Chain of evidence conceptA chain of evidence links clinical validity (test performance) to clinical utility; without clinical validity no inference to utility can be made

Preferred evidenceDirect evidence from RCTs comparing outcomes with and without the test is preferred but absent for many indications

Clinically valid / clinically useful (repeat)

Clinically valid — restatementAbility of a test to detect presence/absence of a condition, future risk, or treatment response; prerequisite for clinical utility assessment

Study criteria implicationStudies should include suitable reference standards and validation cohorts to establish clinical validity

Policy consequenceIf clinical validity is not established, the policy cannot infer clinical utility and may consider the test investigational

Clinically Valid (repeat)

Clinically useful — restatementTest results must inform management decisions that improve net health outcomes to be clinically useful

Evidence preferenceRandomized trials providing direct outcome comparisons are preferred to infer clinical utility

Policy applicationAbsence of direct evidence of improved outcomes supports designation as experimental/investigational for many indications

AANS/CNS recommendation summary

AANS/CNS recommendationAANS/CNS (2015) gave a level III recommendation for adding MRS to anatomic imaging for management of diffuse low‑grade glioma (unclear clinical certainty)

ACR/ASNR guidanceACR‑ASNR‑SPR practice parameters list multiple possible indications and address performance/interpretation details (2019)

NCCN positionNCCN lists MRS as a modality that may help distinguish radiation necrosis from recurrence and assist in grading/targeting biopsy (CNS guidelines)

NCCN guidance summary

NCCN — CNS cancersNCCN (v.2.2024) identifies MRS as one modality to consider to rule out radiation necrosis versus tumor recurrence and to aid grading/targeting biopsy

NCCN — prostate/breastNCCN prostate guidelines list MRS as an advanced imaging technique but make no recommendation; breast guidelines do not mention MRS

Limitations notedNCCN notes limitations including proximity to vessels/air/bone and extra scanner time required

MRS practice parameter (ACR-ASNR-SPR)

Practice parameterACR‑ASNR‑SPR practice parameter (2019) provides guidance on performance and interpretation of CNS MRS

Content focusParameter addresses technical performance, indications when MRI/CT inadequate, and lists possible indications (25 listed)

Appropriateness noteACR considers head MRS without IV contrast usually not appropriate for dementia, head trauma, movement disorders, and neurodegenerative diseases

Frequency and Utilization Notes

MRS frequency note (chunk refs)

Frequency notes — refsSee chunks cited for frequency limits and study selection summaries (chunks 38 and 46 referenced in frequency limits entries)

Policy frequency entriesFrequency limit sections for MRS are present in the policy but no explicit numeric limits are specified in the excerpt

Provider actionCoverage and any frequency restrictions depend on member contract and policy determinations

MRS frequency note (chunk refs)

Study selection criteria — relevance to frequencyStudies considered for validity must report accuracy of marketed technology, include a suitable reference standard, describe patient/sample characteristics and selection, and include a validation cohort separate from development

Implication for repeated testingNo explicit repeat‑testing frequency limits provided; study-quality requirements inform policy decisions about appropriateness of repeat or serial testing

Prior authorization tie‑inRequests for repeat MRS may require justification per study/documentation expectations and member contract

Supporting Literature and Guidance

The literature cited in this policy includes multiple clinical indications evaluated for MRS across neurologic, oncologic, hepatic, and psychiatric disorders. Supporting references cover applications in brain tumors, differentiation of recurrence from radiation necrosis, breast lesion characterization and treatment response assessment, prostate lesion localization, hepatic steatosis, multiple sclerosis, neonatal encephalopathy, traumatic brain injury, carotid plaque evaluation, seizures, and several psychiatric conditions.

Policy Summary

PayerBlue Cross Blue Shield - Kansas

PolicyMagnetic Resonance Spectroscopy (MRS) — Medical Policy

Policy CodePolicy N/A

Change TypeNo material changes

Effective DateJuly 16, 2009

Next Review DateN/A

Key ActionVerify member benefits with Blue Cross and Blue Shield of Kansas Customer Service because MRS is considered experimental/investigational and coverage depends on the member's contract.

SourceLink

On This Page

Policy concludes insufficient direct evidence of outcome benefit.