Characterization of High-Grade Glioma and Solitary Metastasis: An Approach towards Spectroscopy and Advanced Magnetic Resonance Techniques

Aim: The purpose of this article is to analyze different advanced MRI parameters and characterize the efficacy of each one of them in the differentiation of these two pathologies.

Background: The differentiation by means of magnetic resonance between high-grade gliomas and intracranial solitary single metastasis is of the utmost importance since they condition both surgical and complementary treatment. For decades, different methods have been devised to try to differentiate both, given that the final result of surgery and complementary treatment differs substantially between the two. What's more, knowing the possible diagnosis in advance would improve the prognosis of both pathologies.

Methods: Retrospective study that analyzes the parameters of advanced magnetic resonance imaging: spectroscopy, diffusion and perfusion, specifically focused on the differences in the coefficients of the metabolites Cho/Cr, Cho/ NAA and NAA/Cr in peritumoral edema between high-grade gliomas and metastases. The data have been statistically analyzed using ROC (receiver operating characteristic) curves, and cutoff values were obtained.

Results: A total of 79 patients with histologically analyzed tumors were analyzed: 49 high-grade gliomas (40 multiform glioblastomas and 9 anaplastic astrocytomas) and 30 metastases. A statistically significant mean difference was obtained in the three metabolite ratios. The area under the curve for the Cho/NAA ratio was 0.958 (CI: 0.903–1), for Cho/Cr 0.922 (CI: 0.859–0.985) and for NAA/Cr 0.163 (CI: 0.068–0.258; p < 0.001). The cutoff values were 1.115 for Cho/NAA (sensitivity 93.87%, specificity 93.33%, global precision 93.67%); 1.18 for the Cho/Cr ratio (sensitivity 89.79%, specificity 93.33% and precision 91.13%) and 1.155 for the NAA/Cr ratio (sensitivity 67.34%, specificity 93.33%, global precision 44.30%).

Conclusion: The results of the study support the premise that spectroscopy at the level of peritumoral edema is able to differentiate between high-grade gliomas and metastases by showing tumor infiltration in peritumoral edema. This difference allows not only tumor diagnosis but also the possibility of performing high-grade glioma surgery guided by spectroscopy to find tumor infiltration in apparently healthy tissue.