Magnetic resonance spectroscopy and diffusion imaging in the evaluation of neoplastic brain lesions

Abstract

MR spectroscopy and apparent diffusion coefficient (ADC) calculation have been used frequently for tumour grading and differentiation during the last decade. The aim of this study is to evaluate whether the combination of these two techniques can improve the diagnostic effectiveness in patients with brain tumour. Patients and methods: Thirty-six patients with histologically proven brain tumours (7 low, 13 high grade astrocytomas, 11 metastases, and 5 meningiomas) were evaluated with cMRI, MRS and DWI before surgery. Results: MR spectroscopy could differentiate benign from malignant tumours but was not useful in tumour grading. In the differentiation of malignant from benign tumours, N-acetylaspartate (NAA), Choline (Cho), Creatine, lactate/lipid, and alanin ratios were significant. Increase in lipid and alanin could distinguish metastases and meningiomas from other tumours. Increase in the lactate level correlated with the degree of malignancy. ADCs were effective for grading malignant tumours but not for distinguishing tumour types with the same grade. High grade malignant tumours had lower ADC values (0.428 + 0.006 × 10–3 mm2/s) than did low grade malignant (1.6 + 0.325 × 10–3 mm2/s), and benign (1.200 + 0.707 × 10–3 mm2/s) tumours. Conclusion: The combination of MRS with cMRI and calculated ADC values added more and more information to MR imaging in the differentiation and grading of brain tumours and were more useful when done together than each alone.

Keywords

• Magnetic resonance spectroscopy
• Diffusion imaging
• Neoplastic brain lesions