Primary and metastatic intraaxial brain tumors: prospective comparison of multivoxel 2D chemical-shift imaging (CSI) proton MR spectroscopy, perfusion MRI, and histopathological findings in a group of 159 patients.

Background: This study aims to assess the diagnostic value of multivoxel 2D chemical-shift imaging (CSI) proton magnetic resonance (MR) spectroscopy combined with perfusion magnetic resonance imaging (MRI) in the differential diagnosis and grading of brain tumors by comparing neuroimaging data with histopathological findings obtained after resection or biopsy. Methods: A total of 159 patients with a previous brain tumor diagnosis underwent multivoxel 2D CSI proton MR spectroscopy and perfusion MRI. MR spectroscopy multivoxel 2D CSI was performed with an echo time of 30, TR 1,500, FOV 160 mm, acquisition time 7 min 34 s. rCBV maps were evaluated during postprocessing. Statistical analysis was performed on the examination of distributive normality, with logarithmic transformations, Fisher's test, and Bonferroni's test. We used the Pearson's test to compare percentages. Results: In the differential diagnosis between GBM and metastases, MR spectroscopy multivoxel 2D CSI, combined with dynamic contrast enhanced MRI (DCE-MRI) perfusion, reached high sensibility and specificity (p<0.000001). In brain tumor grading, the same method reached high sensibility and specificity (p<0.000001) in distinguishing grade III-IV gliomas but encountered difficulty in determining grades within the two main groups of primary brain tumors, especially where mixed gliomas were involved. Conclusions: The systematic use of CSI spectroscopy and perfusion imaging has shown a high potential in the differential diagnosis and grading of brain tumors. Further exploration into diagnostic procedures that can significantly distinguish between grade III-IV and grade II tumors is needed.