Abstract
1891
Objectives To evaluate the frequency of increased FDG uptake in the hilar lymph node based on the time course after lung radiofrequency (RF) ablation.
Methods One hundred twenty-six patients who met the following inclusion criteria were studied; a) FDG-PET/CT studies were performed before and within 1 year after lung RF ablation, and b) absence of nodal metastasis was proved by at lease 1 year follow-up and radiological findings. Patients were divided into 3 groups based on the time point when PET/CT examination was done after lung RF ablation; 1-3 months group (n=56), 4-6 months group (n=55) and 6-12 months group (n=15). Maximum SUV (SUVmax) of hilar node in the treated side was calculated in each PET/CT study, and the %-change in SUVmax after lung RF ablation was evaluated. An increase of 25% or more was considered to be significant.
Results Mean SUVmax in the hilar node significantly increased until 6 months after lung RF ablation; 2.4±0.6 to 2.6±0.8 in the 1-3 months group (p=0.01), and 2.3±0.6 to 2.5±1.1 in 4-6 months group (p=0.02). However, there was no significant change shown in hilar nodal SUVmax in the 7-12 months group; 2.4±0.4 to 2.3±0.2, (p=0.09). Significant increases (25% or more) in nodal SUVmax was found in 16.1% (9/56) in the 1-3months group, 25.5% (14/55) in the 4-6 months group, and 0% (0/15) in the 7-12 months group. The percentage of significant increase in nodal SUVmax was significantly higher in the 4-6 months group than the 6-12 months group (p<0.04).
Conclusions An increase in FDG accumulation in the hilar node is not a rare finding until 6 months after lung RF ablation. It is important to be aware of this phenomenon, as it can be mistaken for nodal metastasis