Magnetic resonance spectroscopy measures levels of different metabolites in body tissues and produces an image of resonances that correspond to different molecular arrangements of the “excited” isotopes. Magnetic resonance spectroscopic imaging (MRSI) in addtion incorporates imaging to produce spatially localized spectra from within the sample or patient.
The role of MRS in diagnosis and therapeutic planning has not been established by adequate clinical studies. There have been no credible prospective clinical trials demonstrating improved outcomes in patients evaluated with MRS compared to patients evaluated with conventional imaging modalities. The consensus of experts is that further studies are necessary.
An assessment of MRS prepared by the Tuft’s-New England Medical Center Evidence-Based Practice Center for the Agency for Healthcare Research and Quality (AHRQ) (Jordan et al, 2003) states: “Human studies conducted on the use of MRS for brain tumors demonstrate that this non-invasive method is technically feasible and suggest potential benefits for some of the proposed indications. However, there is a paucity of high quality direct evidence demonstrating the impact on diagnostic thinking and therapeutic decision-making. In addition, the techniques of acquiring the MRS spectra and interpreting the results are not well standardized. In summary, while there are a large number of studies that confirm MRS’ technical feasibility, there are very few published studies to evaluate its diagnostic accuracy and whether it can positively affect diagnostic thinking and therapeutic choice. Those studies that do address these areas often have significant design flaws including inadequate sample size, retrospective design and other limitations that could bias the results.”
A review of MRS for evaluation of suspected brain tumor by the BlueCross BlueShield Association Technology Evaluation Center (2003) concluded that “[t]he evidence is insufficient to permit conclusions concerning the effect of magnetic resonance spectroscopy on health outcomes.”
The Center for Medicare and Medicaid Services (2004) has determined that there is insufficient evidence to deem MRS “reasonable and necessary” for brain tumor diagnosis. Due to “methodological shortcomings” in the 11 studies reviewed on the use of MRS for brain lesion detection and a lack of a controlled comparison of MRS and traditional diagnostic strategies, CMS has announced that it will continue its current national non-coverage determination. Guidelines on bone tumors by ACR’s expert panel on musculoskeletal imaging (Morrison et al, 2005) noted that MRS has potential to differentiate benign from malignant lesions, but recommended more research.
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