Complementary value of 11C-choline PET/CT to 18F-FDG PET/CT for diagnosing nasopharyngeal and hepatocellular carcinoma

Abstract

Objective To evaluate the complementary value of 11C-choline (CHO) PET/CT to 18F-FDG PET/CT in the staging of locally advanced nasopharyngeal carcinoma (NPC) and diagnosis of HCC.Methods From December 2007 to January 2010,15 patients with locally advanced NPC and 76 patients with HCC were prospectively enrolled into this study.The research was approved by the ethics committee,and all patients signed informed consents.Whole body 18 F-FDG PET/CT scans were performed on all patients and regional 11C-CHO PET/CT was conducted in 43 patients (15 with NPC,28 with HCC).A lesion with increased uptake of either 11 C-CHO or 18F-FDG was considered positive.SUVmax,tumor/brain (T/B) ratio and tumor/liver (T/L) ratio were calculated for semi-quantitative analysis.Two-sample t test,x2 test,Fisher exact test and linear correlation analysis were used for statistical analysis.Results (1) The lesion SUVmax of 18 F-FDG was higher compared to 11C-CHO (12.81 ± 5.00 vs 6.84 ± 2.76 ; t =6.416,P ＜0.01) in NPC patients.However,11C-CHO PET/CT had a much higher T/B ratio than 18F-FDG (18.62 ±7.95 vs 1.38 ±0.59 ; t =8.801,P ＜ 0.01).Significant correlation was found between the 2 tracers with regard to NPC lesion uptake (r =0.712,P ＜0.01).Compared with 18F-FDG PET/CT,11C-CHO PET/CT had better delineation of intracranial invasion in 50.0％ of patients (12/12 vs 6/12; x2 =8.000,P ＜0.05),skull base invasion in 4/14 patients and orbital invasion in 3/3 patients.(2) 18F-FDG PET/CT showed positive findings in 63.1％ (48/76) of HCC patients.In 28 HCC patients with negative findings on 18F-FDG PET/CT,11 C-CHO PET/CT was positive in 71.4％ (20/28) of patients.The dual-tracer PET/CT improved the diagnostic sensitivity (89.5％,68/76) of HCC compared with 18F-FDG PET/CT (63.1％,48/76) alone (x2 =14.559,P ＜0.01).11C-CHO PET/CT was more sensitive than 18F-FDG PET/CT for the detection of well differentiated HCC (6/9 vs 35.7％ (5/14) ; P =0.214).For the detection of moderately differentiated HCC,the sensitivity of 11C-CHO and 18F-FDG PET/CT was similar to each other (6/7vs 72.0％ (18/25),P =0.648).11C-CHO PET/CT was more sensitive than 18F-FDG for the detection of HCC lesions ＜5.0 cm (72.7％ (16/22) vs 42.1％ (16/38) ; x2 =5.249,P ＜0.05),especially for lesions ＜ 2.0 cm (5/7 vs 0/7; P =0.021).Conclusions 11 C-CHO PET/CT could improve the accuracy in T staging of NPC.It might also play a complementary role for 18 F-FDG PET/CT in the detection of HCC. Key words: Nasopharyngeal neoplasms ; Hepatoma; Tomography, emission-computed ; Tomography, X-ray computed; Choline ; Deoxyglucose