Diffusion restriction associated with bevacizumab treatment in recurrent glial tumors, evaluation of survival with ADC measurement analysis.

Abstract

Recurrent glial tumors treated with bevacizumab often develop diffusion restriction. In this study, we investigated the diffusion restriction pattern after bevacizumab treatment along with the relationship between apparent diffusion coefficient (ADC) values of regions with diffusion restriction and survival period as there are conflicting results on this relationship. We retrospectively identified 24 patients treated with bevacizumab for recurrent glial tumor who had low ADC values after the onset of the treatment. Magnetic resonance imaging (MRI) findings were analyzed for the presence of restricted diffusion, time to onset, location, duration of restriction, and persistence of restriction after cessation of bevacizumab treatment. A retrospective study was performed to investigate the relationship between ADC values obtained at first post-bevacizumab scan and survival periods. Diffusion restriction appeared 2 to 6 months after the onset of bevacizumab therapy and persisted up to 24 months while on bevacizumab. The restricted diffusion persisted up to 6 months after cessation of bevacizumab. Our results showed that there is a negative correlation between ADC values and progression free survival as well as overall survival. Patients having diffusion restriction areas with lower ADC values after the initiation of bevacizumab treatment, are found to have increased overall and progression free survival (p<0.05). In patients with recurrent glial tumor treated with bevacizumab, diffusion restriction can be observed and the ADC values obtained from these areas at first post-bevacizumab MRI scan correlate with progression free and overall survival with the worst survival seen in patients with higher ADC values which therefore can be considered as an imaging marker that can predict the prognosis.