The Quantification of Radiation Fibrosis Using Clinically Indicated Magnetic Resonance Imaging for Head and Neck Cancer Patients

Currently, no objective method exists to measure the extent of fibrosis in swallowing musculature in head and neck cancer (HNC) patients. We developed and psychometrically tested a method of quantifying fibrosis volume using magnetic resonance imaging (MRI). The overall aim of this study was to determine if clinical MRI is a reliable tool to measure fibrosis of the pharyngeal musculature in patients with HNC managed with RT and to assess its potential to capture changes in fibrosis over time. Eligible participants were adults with HNC treated with radiation therapy (RT) who received minimally two MRIs and videofluoroscopic swallow (VFS) studies from baseline (pre-RT) up to 1-year post-RT. Two neuroradiologists independently contoured fibrosis volume in batches from MRIs using Vitrea™. Sufficient inter-rater reliability was set at Intraclass Correlation Coefficient (ICC) > 0.75. Two speech-language pathologists independently rated VFSs for swallowing impairment using standardized scales, with discrepancies resolved by consensus. MRI and VFS scores were correlated using Spearman’s rank coefficient. Participants included 42 adults (male = 33); mean age 59 (SD = 8.8). ICC (95% Confidence Interval) for fibrosis volume was 0.34 (0, 0.76) for batch one and 0.43 (0, 0.82) for batch two. Consensus meetings were held after each batch. Sufficient reliability was reached by batch three (ICC = 0.95 (0.79, 0.99)). Fibrosis volume increased significantly from 3 to 12 months (mean change = 1.28 mL (SD = 5.21), p = 0.006), as did pharyngeal impairment from baseline to 12 months (mean score change = 3.05 (SD = 3.02), p = 0.003). Fibrosis volume moderately correlated with pharyngeal impairment at 3 and 12 months (0.49, p = 0.004 and 0.59, p = 0.005, respectively). We demonstrated a reliable measure of fibrosis volume in swallowing musculature from existing clinical MRIs and identified that larger fibrosis volume was associated with worse swallowing function. The reliable capture of fibrosis volume offers a pragmatic method for early detection of fibrosis and concomitant dysphagia.