Pre-treatment PET/MRI based FDG and DWI imaging parameters for predicting HPV status and tumor response to chemoradiotherapy in primary oropharyngeal squamous cell carcinoma (OPSCC)

Abstract

Objectives: To determine the feasibility of pre-treatment primary tumor FDG-PET and DWI-MR imaging parametersin predicting HPV status and the second aim was to assess the feasibility of those imaging parameters topredict response to therapy.Material and Methods: We retrospectively analyzed primary tumors in 33 patients with proven OPSCC. PET/MRIwas performed before and 6 months after chemo-radiotherapy for assessing treatment response. PET Standardizeduptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV), and apparentdiffusion coefficient (ADC) from pre-treatment measurements were assessed and compared to the clinicopathologicalcharacteristics (T stages, N stages, tumor grades, HPV and post-treatment follow up). HPV was correlatedto the clinicopathological characteristics.Results: ADCmean was significantly lower in patients with HPV+ve than HPV-ev, (P = 0.001), cut off value of (800± 0.44*10-3mm2/s) with 76.9% sensitivity, and 72.2% specificity is able to differentiate between the two groups.No significant differences were found between FDG parameters (SUVmax, TLG, and MTV), and HPV status, (P =0.873, P = 0.958, and P = 0.817), respectively. Comparison between CR and NCR groups; ADCmean, TLG, andMTV were predictive parameters of treatment response, (P = 0.017, P = 0.013, and P = 0.014), respectively.HPV+ve group shows a higher probability of lymph nodes involvement, (P = 0.006)Conclusion: Our study found that pretreatment ADC of the primary tumor can predict HPV status and treatmentresponse. On the other hand, metabolic PET parameters (TLG, and MTV) were able to predict primary tumorresponse to therapy.