Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a functional imaging modality that can quantify tissue permeability and blood flow. Due to vasculature changes resulting from radiation therapy (RT), DCE-MRI quantitative parameters should be significantly different in regions receiving a high radiation dose compared to regions receiving a low radiation dose. This work sought to determine if a significant difference exists in post head and neck cancer (HNC)-RT DCE-MRI quantitative parameters K trans and v e between regions of the mandible receiving a high radiation dose and regions of the mandible receiving a low radiation dose. DCE-MRI was acquired from HNC subjects post-RT. The DCE-MRI quantitative parameters K trans and v e were obtained through Tofts model fitting. Four mandible sections (left ramus, left body, right ramus, and right body) were delineated on subject mandible contours. Two Kruskal-Wallis tests comparing the mean K trans and v e in low dose (≤ 60 Gy) areas of the four mandible regions were computed. Next, two Wilcoxon signed-rank tests were used to determine if the means of K trans and v e between high dose (> 60 Gy) and low dose (≤ 60 Gy) mandible regions were significantly different. To account for multiple statistical tests, a Bonferroni corrected significance level for all statistical tests was used . 48 HNC subjects were included in the analysis. The Kruskal-Wallis tests showed no inherent significant difference in K trans means between mandible regions and no inherent significant difference in v e means between mandible regions . No significant difference was found between high and low dose K trans mandible means ( W =392, p =0.044). A significant difference was found between high and low dose v e mandible means ( W =214, p =0.00013). No inherent difference in DCE-MRI quantitative parameters was observed within subject mandibles, but a significant difference was observed between v e means of high and low radiation dose mandible regions. These results provide evidence of the utility of DCE-MRI to monitor mandible vasculature changes resulting from head and neck cancer radiation therapy. Monitoring post HNC-RT mandible vasculature changes is important to initiate earlier toxicity management and ultimately improve HNC survivor quality of life. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can detect relative differences in anatomical blood perfusion and vessel permeability. Differences in vascularity should occur between mandible regions receiving a large radiation dose and regions receiving a low radiation dose during head and neck cancer radiation therapy. In this study, we determined if DCE-MRI can be used to detect vasculature differences between mandible regions irradiated with high and low amounts of radiation. The results indicate that one of the DCE-MRI parameters was significantly different between irradiated mandible regions receiving high and low radiation dose. This parameter may be used as an early marker for mandible radiation damage from head and neck radiation therapy.
Reber et al. (Fri,) studied this question.