Magnetic Resonance Spectroscopy in Cerebral Gliomas: Biologic Markers
Study Objective: To analyse the prognostic importance of metabolic changes in identification of tumour malignancy in patients with cerebral gliomas, duration of a recurrence-free period and expectancy of life following magnetic resonance spectroscopy results. Study Design: Open diagnostic comparative observational study of "occurrence - monitoring" type. Materials and Methods. The study enrolled 39 patients with cerebral tumours: 17 - with diffusive astrocytomas, 13 - with anaplastic astrocytomas, 9 - with glioblastomas. The mean age of patients was 44.26 ± 14.66 years old. The control group included 9 healthy volunteers of 25.6 + 2.07 years old. Relapse-free period and life expectancy were assessed for 26 out of 39 patients: 10 - with diffusive astrocytomas, 9 - with anaplastic astrocytomas, 7 - with glioblastomas. All patients underwent MR imaging and spectroscopy. All spectra showed metabolites: choline (Cho), creatine (Cr), N-acetylaspartate (NAA), lactate. Study Results. The common characteristic of tumours was significant drop in NAA and Cr levels and increased Cho level. Also statistically significant reduction in NAA/Cho ratio and NAA/Cr ratio was noted in patients with all types of brain tumours vs. controls. Cho/Cr ratio was significantly higher in patients with anaplastic astrocytomas and glioblastomas vs. healthy subjects. Tumour grade was higher with increased Cho/Cr ratio. NAA/Cho ratio was statistically different in patients with low grade (grade II) and high grade (grade III, grade IV) tumours. No significant difference was observed between grade III and grade IV. NAA/Cr ratio was not significantly different in patients with tumours of various grades. Statistically significant (p < 0.05) difference was observed in life expectancy of patients depending on Cho/Cr ratio (division as per top quartile): median life expectancy with Cho/Cr up to 2.67 was 2,000.6 days, where Cho/Cr exceeded the top quartile, the value made 287.8 days. Also, statistically significant (p < 0.05) difference was observed in relapse-free period depending on Cho/Cr ratio (division as per top quartile): with Cho/Cr up to 2.67 it was 860.5 days (median value), where Cho/Cr exceeded the top quartile, the value made 145 days. Conclusion. Cho/Cr ratio makes it possible to propose the rate of brain tumour malignancy and may be a non-invasive biological marker of a relapse-free period and life expectancy of patients.