Post head and neck cancer radiation therapy dynamic contrast enhanced magnetic resonance imaging association with high mandibular radiation dose.

BACKGROUND

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 ve between regions of the mandible receiving a high radiation dose and regions of the mandible receiving a low radiation dose.

METHODS

DCE-MRI was acquired from HNC subjects post-RT. The DCE-MRI quantitative parameters K trans and ve 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 ve 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 ve 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 α = 0.05 4 = 0.0125 .

RESULTS

48 HNC subjects were included in the analysis. The Kruskal-Wallis tests showed no inherent significant difference in K trans means between mandible regions ( χ ( 3 ) 2 = 5.61 , p=0.13) and no inherent significant difference in ve means between mandible regions ( χ ( 3 ) 2 = 0.92 , p=0.82). 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 ve mandible means (W=214, p=0.00013).

CONCLUSIONS

No inherent difference in DCE-MRI quantitative parameters was observed within subject mandibles, but a significant difference was observed between ve 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.