The Preliminary Application Of Trimodality PET/CT-MRI In Head And Neck Squamous Cell Carcinoma

Objective: The purpose of this study was to analysis image characteristics of 18F-FDG PET-positive lesions of head and neck squamous cell carcinoma(HNSCC) with trimodality PET/CT-MRI.Methods: 40 consecutive patients referred for primary staging of HNSCC underwent sequential whole body 18F-FDG PET/CT and MRI imaging of the head and neck in a trimodality PET/CT-MRI system. Imaging quality, fusion quality, lesion conspicuity and lesion characteristics were assessed by two readers independently. The Friedman M test was used for comparisons of imaging quality, fusion quality and lesion conspicuity. The Kappa value was used to evaluate inter-observer agreement.Results: 90 lesions were evaluated by PET/CT and PET/MRI totally, including 40 primary tumors and 50 metastasis nodes. Similar imaging quality and fusion quality were performed by PET/CT?PET/MRIT1 WI and PET/MRIT2WI(P>0.05). As to the lesion conspicuity of primary tumors and metastasis nodes, PET/MRIT1 WI and PET/MRIT2 WI performed significantly better than PET/CT(P<0.05). For the lesion characteristics of primary tumors, PET/MRIT2 WI was considered superior to PET/CT in 72.5% of lesions, for the lesion characteristics of metastasis nodes, PET/MRIT2 WI was considered superior to PET/CT in 34.0% of lesions, equal to PET/CT in 64.0% of lesions.Conclusion: The results of the present study provide evidence that PET/MRI imaging can serve as a legitimate alternative to PET/CT in the clinical workup of patients with HNSCC.Objective: The purpose of this study was to explore the application of intravoxel incoherent motion diffusion weighted imaging(IVIM-DWI) in nasopharyngeal carcinoma(NPC) with trimodality PET/CT-MRI system. We analyzed the reproducibility of IVIM-DWI on NPC and investigated the differences of ADCstandard, D*, D and f values between primary tumors and metastatic nodes. We also evaluated whether SUV and ADCstandard, D*, D and f values are correlated or independent in patients with NPC using a trimodality PET/CT-MRI system.Methods: We included 20 patients with histologically confirmed NPC who underwent whole body PET/CT, regular head and neck MRI and multiple b value DWI with the trimodality PET/CT-MRI system before treatment. Two experienced readers measured each parameter independently, maximum SUV(SUVmax) and mean SUV(SUVmean) of volume of interest(VOI) were measured by the accompanied software, the true diffusion coefficient(D), pseudo diffusion coefficient(D*) and perfusion fraction(f) were obtained according to the biexponential model, and the standard apparent diffusion coefficient(ADCstandard) was obtained according to the monoexponential model. Two weeks later, measurements were repeated by the two readers, independently. Intra- and inter-observer agreement for ADCstandard, D*, D and f values' measurements was assessed. Differences of ADCstandard, D*, D and f values between primary tumors and metastatic nodes were tested. Pearson correlations were calculated to investigate the association between SUV and ADCstandard, D*, D and f values.Results: We accessed 20 primary tumors and 29 metastatic nodes in 20 patients with NPC. Intraclass correlation coefficient(ICC) analysis showed almost perfect reproducibility(ICC 0.836~0.990) for ADCstandard, D*, D, f values for intra-observer and inter-observer agreement. The Bland-Altman plots demonstrated good consistency of ADCstandard, D*, D, f values. In comparison to metastatic nodes, the primary tumors had significantly higher ADCstandard value and D value, and lower D* value. Pearson's correlation analysis showed no significant correlation between primary tumors' SUVmax/SUVmean and ADCstandard, D*, D and f values, values of r were 0.216/0.210,-0.123/-0.135, 0.215/0.223, 0.088/0.057, respectively. Pearson's correlation analysis also showed no significant correlation between metastatic nodes' SUVmax/SUVmean and ADCstandard, D*, D and f values, values of r were 0.295/0.318, 0.130/0.132, 0.251/0.296, 0.287/0.286, respectively.Conclusion: Our data suggest that IVIM-DWI is reproducible on NPC, SUVmax/SUVmean and ADCstandard, D*, D and f values are independent biomarkers in NPC primary tumors and metastasis nodes. There were physiological differences between the primary NPC and metastasis nodes. After appropriate validation, these findings might be useful in optimizing treatment planning and improving patient care.