Abstract
It is often difficult to make a correct diagnosis of ring‐like enhanced lesions on Gd‐enhanced MR brain images. To differentiate these lesions using proton MR spectroscopy (^1^H‐MRS), we retrospectively evaluated the correlation between the ^1^H‐MR spectra and histopathological findings. We evaluated proton MR spectra obtained from the lesions in 45 patients, including metastasis (n = 19), glioblastoma (n = 10), radiation necrosis (n = 7), brain abscess (n = 5), and cerebral infarction (n = 4). The rate of misdiagnosis was found to be lowest at the threshold level of 2.48 for the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) obtained from the whole lesions, which include the enhanced rim and the non‐enhanced inner region. That is, the positively predictive values of a Cho/Cr greater than 2.48 for diagnosing metastasis or glioblastoma was 88.9 and 60.0%, respectively, and the positively predictive value of a Cho/Cr less than 2.48 for diagnosing radiation necrosis or cerebral infarction was 71.4 and 100%, respectively. For further differentiating between metastasis and glioblastoma, information about the presence and absence of an N‐acetyl‐aspartate (NAA) peak and lipid‐ or lactate‐dominant peak was found to be useful. In 73.7% of metastasis cases a lipid‐dominant peak was observed in the whole lesion without an NAA peak in the inner region, whereas the same pattern was observed in only 10% of the glioblastoma cases.
Correlation with the histopathological findings showed that a high Cho signal is suggestive of neoplasm. Lipid signal in the non‐enhanced central region was correlated to necrosis. Lactate signals were often observed in glioblastoma, abscess and sometimes metastasis, presumably reflecting the anaerobic glycolysis by the living cells in the ring‐like enhanced rim. Single‐voxel proton MR spectroscopy may serve as a potential tool to provide useful information of differentiation of ring‐like enhanced lesions that cannot be diagnosed correctly using enhanced MR images alone. Copyright © 2001 John Wiley & Sons, Ltd.