Radiation injury of the parotid glands during treatment for head and neck cancer: assessment using dynamic contrast-enhanced MR imaging.

The parotid gland is an important organ at risk of complications of radiotherapy for head and neck cancer. In this study, we examined the potential of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for assessment of radiation injury to the parotid glands. DCE-MRI was performed before and 3 months after radiotherapy in patients treated for head and neck cancer. DCE-MRI was analyzed using the pharmacokinetic model proposed by Tofts and Kermode to produce three DCE parameters: k(trans), v(e) and v(p). These parameters were correlated with the dose of radiation delivered to the parotid glands and the degree of radiation-induced parotid atrophy. The mean radiation dose received by the parotid glands was 47.1 ± 6.6 Gy. All patients received concurrent chemotherapy. There was a significant rise in all three parameters after therapy (P < 0.0001). Baseline v(e) and v(p) and the post-treatment rise in v(e) correlated with parotid gland atrophy (P  =  0.0008, 0.0003 and 0.0022, respectively). DCE-MRI has the potential to be used as a non-invasive technique for predicting and assessing radiation injury in the parotid glands.