Effect of Radiation on DCE-MRI Pharmacokinetic Parameters in a Rabbit Model of Compromised Maxillofacial Wound Healing: A Pilot Study

Abstract

Osteoradionecrosis (ORN), a potentially debilitating complication of maxillofacial radiation, continues to present a challenging clinical scenario, with limited treatment options that often fail. Translational animal models that can accurately mimic the human characteristics of the condition are lacking. In the present pilot study, we aimed to characterize the effects of radiation on the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) pharmacokinetic parameters in a rabbit model of compromised maxillofacial wound healing to determine its potential as a translational model of ORN. An experimental group underwent fractionated radiation of the mandible totaling 36Gy. At 4weeks after irradiation, the experimental and control groups (n=8 rabbits each) underwent a surgical procedure to create a critical size defect in the mandibular bone. DCE-MRI scans were acquired 1week after arrival (baseline; time point 1), 4weeks after completion of irradiation in the experimental group (just before surgery, time point 2), and 4weeks after surgery (time point 3). No differences in the analyzed DCE-MRI parameters were noted within the experimental or control group between the baseline values (time point 1) and those after irradiation (time point 2). The whole blood volume fraction (vb) in the experimental group was increased compared with that in the control group after irradiation (time point 2; P<.05). After surgery (time point 3), both the forward flux rate of contrast from blood plasma and the extracellular extravascular space and the vb were increased in the control group compared with the experimental group (P<.05). The results of the present study suggest that DCE-MRI of a rabbit model of compromised maxillofacial wound healing could reflect the DCE-MRI characteristics of human patients with ORN and those at risk of developing the condition. Future studies will focus on further characterization of this rabbit model as a translational preclinical model of ORN.