MRS Detects Brain Tumor Biomarker

A new magnetic resonance spectroscopy (MRS) technique may offer a new approach to identify and track a protein associated with a genetic mutation in brain tumor cancer cells.
The imaging modality could determine a diagnosis of glioma and provide prognostic information, according to new research.

The study’s findings were published online January 26, 2012, in the journal Nature Medicine. The MRS technique provides a definitive diagnosis of cancer based on imaging of a protein, 2HG, which is associated with a mutated gene (IDH1 or IDH2), found in 80% of low- and intermediate-grade gliomas. The presence of the mutation also means a better prognosis.

“To our knowledge, this is the only direct metabolic consequence of a genetic mutation in a cancer cell that can be identified through noninvasive imaging,” said Elizabeth Maher, MD, associate professor of internal medicine and neurology at the University of Texas (UT) Southwestern Medical Center (Dallas, USA).

UT Southwestern researchers developed the technique by modifying the settings of a 3T MRI system to monitor the level of the 2HG protein. Earlier studies linked high levels of the protein to the mutation. “Our next step is to make this testing procedure widely available as part of routine MRIs for brain tumors. It doesn’t require any injections or special equipment,” said Maher.

To confirm the test as a diagnostic tool, biopsy samples from 30 glioma patients enrolled in the UT Southwestern clinical trial were analyzed; half had the mutation and expected high levels of the protein. MRS imaging of these patients conducted prior to surgery predicted, with 100% accuracy, which patients had the mutation.

“These data show that the presence of a 2HG peak in MRS is 100 percent correlated with the presence of a mutation in IDH1 or IDH2 and elevated concentrations of D-2HG in the tumor,” wrote Dr. Maher and colleagues, adding that the method is both highly sensitive and specific.

The researchers concluded by noting that the method could be easily and relatively quickly transferred into clinical practice. 3T MRI systems are becoming more available and the data acquisition method uses standard hardware. In addition to providing diagnostic and prognostic data, the method could offer a useful measurement during treatment and follow up, and potentially evaluate therapeutic response. Biomarker monitoring may help with the clinical management of patients with gliomas, who typically have a long period marked by minimal disease progression, followed by aggressive growth and conversion to high-grade disease.

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University of Texas Southwestern Medical Center