Intravoxel Incoherent Motion Imaging Kinetics during Chemoradiotherapy for Human Papillomavirus-Associated Squamous Cell Carcinoma of the Oropharynx: Preliminary Results from a Prospective Pilot Study

摘要

This study aims to identify the temporal kinetics of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) in patients with human papillomavirus-associated (HPV+) oropharyngeal squamous cell carcinoma. Patients were enrolled under an IRB-approved protocol as part of ongoing prospective clinical trial. All patients underwent two MRI studies, a baseline scan before chemoradiotherapy and a midtreatment scan 3–4 weeks of treatment initiation. Parametric maps representing pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), and apparent diffusion coefficient (ADC) were generated. The Mann-Whitney U test was used to assess temporal variation of IVIM metrics. Bayesian quadratic discriminant analysis (QDA) was used to evaluate the extent to which midtreatment changes in IVIM metrics could be combined to predict sites that would achieve complete response (CR) in multivariate analysis. A total of 31 patients were included in the final analysis with 59 lesions. Pretreatment ADC and D values of the complete response (CR) lesions (n=19) were significantly lower than non-CR lesions (n=33). Midtreatment ADC, D, and f values were significantly higher (P < .0001) than pretreatment values for all lesions. Each increase in normalized ΔADC of size 0.1 yielded a 1.45-fold increase in the odds of CR (P<.0003), each increase in normalized ΔD of size 0.1 yielded a 1.53-fold increase in the odds of CR (P<.0002), and each unit increase in Δf yielded a 2.29-fold increase in the odds of CR (P < .02). Combined ΔD and ΔADC were integrated into a multivariate prediction model and attained an AUC=0.87 (95% CI: 0.79, 0.96) as well as sensitivity=0.63, specificity=0.85, and accuracy=0.78 under leave-one-out cross-validation. In conclusion, IVIM is feasible and potentially useful in prediction and assessment of early response of HPV+ oropharyngeal squamous cell carcinoma to chemoradiotherapy.