# Post-RT Head and Neck DCE-MRI: Association Between Mandibular Dose and ve

## TL;DR

This study shows that DCE-MRI can detect changes in mandible blood vessel permeability after head and neck cancer radiation therapy.

## Contribution

The study demonstrates that the DCE-MRI parameter ve can serve as an early marker for radiation-induced mandible damage.

## Key findings

- The DCE-MRI parameter ve was significantly different between high- and low-dose mandible regions.
- No inherent differences in ve were found within mandible regions, but dose-related differences were observed.
- Ktrans showed significant regional differences in the mandible, but ve was more indicative of radiation dose effects.

## Abstract

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 whether 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, ve, 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.

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 study sought to determine whether a significant difference exists in post-head-and-neck-cancer (HNC)-RT DCE-MRI quantitative parameters (Ktrans 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 Ktrans 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 Friedman tests comparing the mean Ktrans and ve in low-dose (≤60 Gy) areas of the four mandible regions were computed. If the Friedman test determined that a significant difference for a parameter between mandible regions exists, post hoc Wilcoxon signed-rank tests were completed comparing the four mandible regions. If the Friedman test determined that there was no significant difference between mandible regions, a Wilcoxon signed-rank test was used to determine whether a significant difference exists in the parameter between high-dose (>60 Gy) and low-dose (≤60 Gy) mandible regions. Results: 48 HNC subjects were included in the analysis. The Friedman tests showed no significant difference in ve means between mandible regions (χ(3)2 = 1.63, p = 0.44) and a significant difference in Ktrans means between mandible regions (χ(3)2 = 10.29, p = 0.005). Post hoc testing between Ktrans mandible regions found that the left body and right body differed significantly from the left ramus and right ramus. The Wilcoxon signed-rank test comparing the mean ve between high- and low-dose mandible regions found a significant difference (W = 214, p = 0.00013). Conclusions: no inherent difference in the DCE-MRI quantitative parameter ve was observed within subject mandibles, but a significant difference was observed between ve means in 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 survivors’ quality of life.