Primary brain tumors: Proton magnetic resonance spectroscopic analysis and histopathological correlation

Abstract

Objective: Recent advances in treatment of primary brain tumors have increased the interest in radiological imaging in respect to both the diagnosis of tumor and the evaluation of the efficiency of therapy. Conventional Magnetic Resonance (MR) imaging is commonly used for diagnosis and follows up of the primary brain tumors, but it fails in grading of the tumors. MR spectroscopy permits in-vivo biochemical evaluation of brain lesions. Methods: Twenty three patients with histopathologic diagnosis of primary brain tumor and control group consisting of 23 healthy volunteers were investigated. In addition to conventional MR imaging of all patients were underwent point resolved spectroscopy (PRESS) sequence via single voxel MR spectroscopy. Using MR spectroscopy, metabolites [N-acetyl aspartate (NAA), choline (Cho), myo-inositol (mI), lipid, lactate and alanine] and their ratio to creatine (Cr) were measured quantitatively. Results: MR spectroscopic imaging of neuroglial primary brain tumors revealed that the NAA/Cr and mI/Cr ratios were decreased. In extra axial primary brain tumors, which consist of meningioma, NAA wasn’t detected, Cho/Cr ratio was remarkably increased, mI/Cr, lipid/Cr and lactate/Cr ratios were mildly increased. Alanine peak was detected only in meningioma. In high grade neuroglial tumors in proportion to low grade ones NAA/Cr and mI/Cr ratios were decreased, Cho/Cr, lipid/Cr and lactate/Cr ratios were remarkably increased. Conclusion: MR spectroscopy provides extra information in classification of primary brain tumors as intra-axial and extra-axial, and in grading of neuroglial primary brain tumors as high grade or low grade. It was concluded that using conventional MR imaging in cooperation with MR spectroscopy is beneficial in differential diagnosis and in grading of primary brain tumors.