Comparison of 13N-NH3 and 18F-FDG PET/CT in the evaluation of gliomas / 中华核医学与分子影像杂志

ABSTRACT

Objective To investigate the diagnostic efficacy of 13N-NH3 and 18F-FDG PET/CT in the evaluation of untreated gliomas.Methods A total of 45 consecutive patients (29 males,16 females;age range 14-75 years,average age (47.47± 15.64) years) with final diagnosis of glioma from August 2009 to May 2012 were retrospectively analyzed.PET/CT imaging was performed with both 18F-FDG and 13N-NH3.Imaging results were analyzed by tumor-to-gray matter (T/G) ratios.ROC curve analysis was conducted to determine the optimal T/G cutoff values between low-grade and high-grade gliomas.One-way analysis of variance was applied to assess the differential efficacy of the two tracers in different grade of glioma.Results Forty-eight separate lesions were identified (WHO grade Ⅱ,n=16;grade Ⅲ,n=12;and grade Ⅳ,n=20).The sensitivities of 13N-NH3 PET/CT and 18F-FDG PET/CT on predicting high-grade gliomas were 91％(29/32) and 66％ (21/32),respectively.The optimal T/G cutoff values for 18F-FDG and 13N-NH3 were 0.64 and 0.86 with the AUC of 0.910 and 0.943,respectively.The sensitivity and positive predictive value of predicting high-grade gliomas with optimal cutoff values were 84％ (27/32) and 93％ (27/29)for 18F-FDG PET/CT,those for 13N-NH3 PET/CT were 94％ (30/32) and 94％ (30/32),respectively.Conclusion 13N-NH3 PET/CT is superior to 18F-FDG PET/CT not only in separating low-grade gliomas from high-grade ones,but also in the detection of high-grade gliomas for better tumor to normal gray matter contrast.