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

Abstract Objective 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). Patients and methods 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, VOI T2 ), diffusion-weighted magnetic resonance imaging (VOI DWI ) and 18 F-fluorodeoxyglucose positron emission tomography (VOI PET ). The overlap percentages of low-metabolic sub-region (cluster 1) and high-metabolic sub-region (cluster 2) in VOI PET and VOI DWI were analyzed by cluster analysis. Results Both the VOI DWI and VOI PET were encompassed in the VOI T2 , respectively 99.6% and 97.5%. The median tumor overlap was 94.4% (VOI DWI within VOI PET ). The median overlap of cluster 2 in VOI PET and VOI DWI was 43.61% (27.67–52.66%) and 21.86%(10.47–40.89%), respectively. The median overlap of cluster 1 in VOI PET and VOI DWI 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. Conclusion 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.