Feasibility of multiparametric imaging with PET/MR in nasopharyngeal carcinoma: A pilot study

•PET/MR for biological characterization and potential therapeutic applications of NPC.•The overlap of VOIDWI and VOIPET for nasopharyngeal carcinoma is not complete.•The volume defined by cluster-analysis might be meaningful for dose painting.•It is meaningful to deduce the information of FDG-PET from DWI-MRI. The aim of this pilot study was to explore the integrated positron emission tomography and magnetic resonance imaging scanner (PET/MR) for biological characterization of nasopharyngeal carcinoma (NPC) and potential therapeutic applications of dose painting (DP). Twenty-one NPC patients with PET/MR were included in this study. Overlap of tumor volumes was analyzed on T2-weighted images (volume of interest, VOIT2), diffusion-weighted magnetic resonance imaging (VOIDWI) and 18F-fluorodeoxyglucose positron emission tomography (VOIPET). The overlap percentages of low-metabolic sub-region (cluster 1) and high-metabolic sub-region (cluster 2) in VOIPET and VOIDWI were analyzed by cluster analysis. Both the VOIDWI and VOIPET were encompassed in the VOIT2, respectively 99.6% and 97.5%. The median tumor overlap was 94.4% (VOIDWI within VOIPET). The median overlap of cluster 2 in VOIPET and VOIDWI was 43.61% (27.67–52.66%) and 21.86%(10.47–40.89%), respectively. The median overlap of cluster 1 in VOIPET and VOIDWI was 48.03% (23.91–63.15%) and 24.40% (7.44–51.44%), respectively. Separation between clusters appeared to be defined by a SUV value. For NPC, the VOIs of DWI and FDG PET were not overlapped completely and the volume defined by cluster-analysis might be meaningful for DP.