Role of in vivo proton MR spectroscopy in the evaluation of adult brain lesions: Our preliminary experience

Context: A definite diagnosis and characterization of intracranial mass lesions, based on structural Magnetic Resonance Imaging (MRI) alone may be difficult. In such cases Proton Magnetic Resonance Spectroscopy (1H-MRS) along with other non-invasive techniques represents an advance in the specificity of brain lesion diagnosis.1 Aims: The primary aim of this study was to evaluate the extent of the utility of 1H-MRS in adult brain tumors and their differentiation from similar-appearing space-occupying lesions. Material and Methods: MRS studies were performed on 1.5 Tesla whole body MR system using standard imaging head coil. Sixty patients (aged 30-65 years), including 35 males (31-65 years) and 25 females (30-65 years) were studied, along with 25 age-matched healthy volunteers (30-64 years). The Student 't' test was used to statistically analyze the spectroscopic data for significant difference in the metabolite ratios of the lesions from normal brain tissue. Results: The Cho/Cr ratio was significantly raised in low and high-grade glioma and meningioma patients (1.85±0.36, 3.50±1.00 and 6.65±2.83 respectively) (mean±standard deviation), as compared with the control group (1.16±0.18); and NAA/Cr and NAA/Cho ratios were found to be lower than normal values in our study (P<0.01). However, in the non-neoplastic lesions, the Cho/Cr ratios were not statistically significant. The tubercular lesions revealed an average Cho/Cr ratio of 1.24±0.18, while it was 1.14±0.07 for infarcts. Conclusions: MR Spectroscopy was useful to arrive at a more definitive diagnosis in doubtful intracranial space-occupying lesions with similar morphological imaging patterns.

Keywords
Glioma, Meningioma, Proton magnetic resonance spectroscopy (1H-MRS), Choline (Cho), Creatine (Cr), N-acetyl-L-aspartate (NAA), Lactate (Lac), lipid.