Diffusion Tensor Imaging Study on Radiation-induced Brain Injury in Nasopharyngeal Carcinoma during and after Radiotherapy

AIMS AND BACKGROUND: The aim of this study was to monitor the mircostructure change of temporal lobe during the acute and subacute stage of radiation-induced brain injury using magnetic resonance diffusion tensor imaging (DTI) in nasopharyngeal carcinoma patients. METHODS AND STUDY DESIGN: Eighty patients diagnosed with nasopharyngeal carcinoma and treated with the first radiotherapy from July 2010 to May 2012 were enrolled. Routine brain magnetic resonance imaging (MRI) and DTI were conducted in all patients before and during radiotherapy (radiation dose was 20, 40, and 60 Gy, respectively). The MRI and DTI were also performed in the 1st, 2nd, and 3rd month after radiotherapy in 47 cases of 80 patients. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of DTI during different stages were dynamically observed and analyzed. RESULTS: The ADC values were increased and the FA values were decreased with the increase of radiation dose (20, 40, and 60 Gy) during the radiotherapy, but there was no significant difference in ADC value or FA value between before and during radiotherapy (p>0.05). Compared with before radiotherapy, the ADC values were significantly increased and the FA values were significantly decreased at the 1st month, 2nd month, and 3rd month after radiotherapy (all p<0.05). CONCLUSIONS: Diffusion tensor imaging reflects the microstructure change of radiation-induced brain injury in the acute and subacute stage, which provides an objective basis for early intervention of potential irreversible brain injury in the late delayed stage, and has important significance for improving the overall efficacy of radiotherapy.