Objective: The objective of this study was to compare the diagnostic performance for detecting local tumor progression between FDG PET and CT in patients who received lung radiofrequency (RF) ablation for the treatment of malignant lung tumors.
Methods: A total of 469 FDG PET/CT studies were performed at 4 time points (3, 6, 9, 12 months) after lung RF ablation in 143 patients (87 male and 56 female patients) with 231 tumors. The SUVmax was calculated in treated tumors in each PET image. The percentage decrease (% decrease) in ablative zone size was evaluated in each CT image. The final response was judged based on follow-up findings and histology. Diagnostic performance of FDG PET and CT images was evaluated using receiver operating characteristic analysis.
Results: Local tumor progression was identified in 37 patients (25.9%, 37/143) having 47 tumors (20.4%, 47/231) during the median follow-up of 24 months (range, 8–75 months). The area under the receiver operating characteristic curve of PET was higher than that of CT at all 4 time points (0.71 vs 0.55 at 3 months, 0.82 vs 0.60 at 6 months, 0.84 vs 0.66 at 9 months, and 0.92 vs 0.68 at 12 months), and its diagnostic performance was significant at each time point (P = 0.0010 at 3 months and P < 0.001 at 6, 9, and 12 months). However, the area under the receiver operating characteristic curve of CT was significant at 9 months (P = 0.040) and 12 months (P = 0.032).
Conclusions: FDG PET/CT is better able to assess local tumor progression at 3 and 6 months after lung RF ablation than CT alone.