Voxel-wise correlation of functional imaging parameters in HNSCC patients receiving PET/MRI in an irradiation setup.

Abstract

The purpose of this study was to demonstrate the feasibility of voxel-wise multiparametric characterization of head and neck squamous cell carcinomas (HNSCC) using hybrid multiparametric magnetic resonance imaging andpositron emission tomography with [18F]-fluorodesoxyglucose (FDG-PET/MRI) in aradiation treatment planning setup. Ten patients with locally advanced HNSCC were examined with acombined FDG-PET/MRI in an irradiation planning setup. The multiparametric imaging protocol consisted of FDG-PET, T2-weighted transverse short tau inversion recovery sequence (STIR) and diffusion-weighted MRI (DWI). Primary tumours were manually segmented and quantitative imaging parameters were extracted. PET standardized uptake values (SUV) and DWI apparent diffusion coefficients (ADC) were correlated on avoxel-wise level. Images acquired in this specialised radiotherapy planning setup achieved good diagnostic quality. Median tumour volume was 4.9 [1.1-42.1] ml. Mean PET SUV and ADC of the primary tumours were 5 ± 2.5 and 1.2 ± 0.3 10-3 mm2/s, respectively. In voxel-wise correlation between ADC values and corresponding FDG SUV of the tumours, asignificant negative correlation was observed (r = -0.31 ± 0.27, p < 0.05). Multiparametric voxel-wise characterization of HNSCC is feasible using combined PET/MRI in aradiation planning setup. This technique may provide novel insights into tumour biology with regard to radiation therapy in the future.