Apparent diffusion coefficient obtained by magnetic resonance imaging as a prognostic marker in glioblastomas: Correlation with MGMT promoter methylation status

Objective: To evaluate whether apparent diffusion coefficient (ADC) values can predict the status of MGMT of glioblastoma multiforme (GBM) and correlate with overall survival (OS) and progression-free survival (PFS). Methods: This retrospective study included 47 patients with pathologically proven glioblastoma. All of them underwent MR DWI study before surgery (mean time 1 week) and the status of methylguanine-DNA-methyltransferase (MGMT) promoter methylation was searched for. Minimum apparent diffusion coefficient (ADC) values were evaluated. OS and PSF parameters were calculated, and Student's t-test, Kaplan-Meier curves, linear and Cox regression were performed. Results: Twenty-five patients showed positive methylation of the MGMT promoter. Patients showing MGMT promoter methylation had higher minimum ADC values, and they survived longer than those without MGMT promoter methylation. The median ADCmin value of 0.80 represents the cutoff value able to distinguish between methylated and un-methylated patients. Patients showing minimum ADC values higher than 0.80 survived longer than patients with minimum ADC values lower than 0.80. A linear correlation between minimum ADC values vs. the OS and PFS was observed. Conclusions: Minimum ADC values in glioblastoma multiforme could be used as a preoperative parameter to estimate the status of MGMT promoter methylation and the survival of patients. Key Points: • Diffusion-weighted MR imaging (DWI) provides new insights into glioblastoma multiforme (GBM) • DWI ADCmin values can predict the methylation status of MGMT promoter. • The MGMT promoter methylation group survived longer than the unmethylated group. • Patients with high ADCmin values survived longer than patients with low values.