Alterations of lactate(+lipid) concentration in brain tumors with in vivo hydrogen magnetic resonance spectroscopy during radiotherapy

RATIONALE AND OBJECTIVES. The authors determine whether assessment of the relative lactate(+lipid) concentration ([r-Lac(Slip)]) obtained from hydrogen magnetic resonance (MR) spectroscopy is useful for predicting the outcome of radiotherapy on brain tumors. METHODS. Fifty-one hydrogen MR spectroscopic studies were performed in eight patients with primary or metastatic brain tumor before and during radiotherapy. The r-Lac(+lip) calculated as the ratio of lactate(+lipid) peak area to total water was compared before and during radiotherapy in each case. The change of tumor volume measured on magnetic resonance images also was compared. RESULTS. The r-lac(+lip) substantially decreased in the radiosensitive cases (three lymphomas and one brain cancer) but did not decrease, even at the end of therapy, in the radioresistant cases (two brain cancers and two glioblastomas). CONCLUSION. Assessment of r-lac(+lip) may adjunctively contribute to the early prediction of the radiotherapeutic effect on brain tumors.