Proton MR spectroscopy (1H-MR spectroscopy, MRS) is a potentially useful adjunct to anatomic MR imaging in the characterization of brain tumors. Proton MR spectroscopy (1H-MR spectroscopy) provides additional information on the metabolic composition within an area of tissue. In August 2002, the American College of Radiology requested that the Center for Medicare and Medicaid Services (CMS) reconsider the 1994 noncoverage decision for 1H-MR spectroscopy. In September 2004, based in large part on 2 technology assessments CMS reaffirmed the existing noncoverage policy, concluding that “… the evidence is not adequate to conclude that 1H-MR spectroscopy is reasonable and necessary… for use in the diagnosis of brain tumors.” Several subsidiaries of large managed care organizations have reached similar noncoverage decisions, though this is far from universal and many carriers have made a decision to cover MRS.
Of the 22 studies that measured diagnostic performance, the largest head-to-head comparison of MR imaging alone versus MR imaging and 1H-MR spectroscopy provided encouraging findings that 1H-MR spectroscopy can make a significant contribution to diagnosis for patients with indeterminate brain lesions.
A number of large diagnostic performance studies have demonstrated that 1H-MR spectroscopy can accurately distinguish between high- and low-grade astrocytomas. This work now needs to be extended to demonstrate: (1) diagnostic thresholds selected a priori, rather than post hoc, can achieve similar diagnostic accuracy, (2) the incremental diagnostic yield of 1H-MR spectroscopy compared with anatomic MR imaging, and (3) that any improvement in tumor grading by 1H-MR spectroscopy leads to a reduction in biopsy rates or changes in therapy. Evidence in other clinical subgroups, such as the use of 1H-MR spectroscopy to distinguish neoplastic and non-neoplastic lesions or to differentiate recurrent tumors from radiation necrosis, is limited by the small number of studies.
W. Hollingwortha, L.S. Medinac, R.E. Lenkinskid, D.K. Shibataa, B. Bernalc, D. Zurakowskie, B. Comstockb and J.G. Jarvika A Systematic Literature Review of Magnetic Resonance Spectroscopy for the Characterization of Brain Tumors American Journal of Neuroradiology 27:1404-1411, August 2006
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