S. Mulder1, M. R. Abdelaal1, C. Dede1, K. A. Wahid2, Y. Khamis3, D. H. El-Habashy1, M. Naser1, R. He1, K. A. Hutcheson4, A. S. Mohamed1,5, S. Y. Lai1,4, and C. D. Fuller1; 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of clinical oncology and nuclear medicine, Faculty of Medicine, Alexandria University, Alexandria, Egypt, 4Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, 5Department of Radiation Oncology, Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX
Purpose/Objective(s): The purpose of this work is to evaluate DCE MRI parameters for monitoring acute response in the muscular tissues of the head and neck (HN) and relate kinetics to post-RT measured swallowing dysfunction via DIGEST, a video fluoroscopy-based grading system. Materials/
Methods: 88 HN cancer (HNC) patients who received definitive RT were enrolled in the prospective study following IRB approval and study-specific informed consent prior to imaging. MRI acquisitions performed at baseline (pre-RT), 3 weeks after treatment start date (Mid-RT), and 3 months post-RT. DIGEST (grade 0-4) assessments for dysphagia were collected between end of RT to 6 months post-RT. 17 swallowing structures were auto segmented on T2W images taken during the same acquisition using atlases on commercial software. These structures were then registered onto the parametric maps to extract median intensity estimations for each parameter, Ktrans, Kep, Ve, and VP - generated with the extended-Tofts model. Mann-Whitney U (p < 0.05) was used to compare delta changes from baseline between groups based on DIGEST score relative to a set threshold. Wilcoxon Signed Rank Test (p < 0.05) was used to generate statistical evidence for each timepoint-DIGEST group change from baseline. Analysis was repeated for varying DIGEST score binarization thresholds. Results: Of the 88 HNC patients, 77 male and 11 female, with 69 (78%) having primary tumors originating from the oropharynx, 9 (10%) had the primary tumor in the oral cavity, 7 (8%) with unknown primary tumor and 3 (3.4%) had primary tumor in the parotid gland. Sixty-three patients (72%) were treated with IMRT/VMAT and 25 (28%) were treated with IMPT. At Mid-RT there were statistically significant increases in ?Kep found in 12/17 (70.6%) of structures in patients binarized into more severe dysphagia group, but at Post-RT, this drops to 3/17 (17.6%) exhibited statistically significant increases. ?Ve exhibited statistically significant differences at post-RT in 1/17 (5.8%) of structures. In ?Ktrans and ?Vp, we did not observe any statistically significant changes between the groups based on DIGEST status. Evaluating timepoints relative to the baseline within each patient using the matched-pair Wilcoxon demonstrated robust changes from baseline with stronger evidence for ?Ktrans and ?Kep in the higher DIGEST group – in concordance with statistical findings when comparing between groups. Conclusion: Our findings demonstrate that acute vascular changes in the muscle tissues of the HN during radiotherapy assessed by DCE MRI provide highly informative monitoring information. This strongly supports further investigation for use as a monitoring biomarker for muscle toxicity to evaluate radiation dose association and additional clinical variables of interest to improve prediction and treatment of dysphagia in HNC patients.
