Findings of radiofrequency ablation in normal dog liver:comparative study of CT,positron emission tomography-CT and histopathology / 中华放射学杂志

ABSTRACT

Objective To evaluate dynamic CT and PET-CT features of normal dog liver after radiofrequency ablation(RFA)correlated with the time-related histopathological changes.Methods Fifteen hybrid adult dogs in good health condition were evenly divided into 5 groups(the immediate,1 st,2 nd,4 th and 8 th week group)according to random digits table methods.Twice RFA was performed for each dog liver.The dogs after RFA underwent CT and PET-CT scanning respectively at the time point defined for each group.All dogs were executed through intravenous injection of klorvess liquid after scanning.Liver samples were histologically examined.All images were assessed to determine the ratios(r_(p/p))which referred to the comparison of rimlike enhancement or tracer uptake in the periphery of the necrosis to that in normal liver parenchyma.Those imaging results were compared and correlated with histopathological findings.Results For the immediate group after RFA procedure,central ablation lesions appeared coagulation necrosis and surrounding sinusoids engorged with blood.On the images of enhanced CT,marked rimlike enhancement was noticed in peripheral ablation lesions.While PET-CT showed decreased ~(18)F-FDG uptake surrounded by homogeneous tracer distribution.For the 1 st-4 th week group,central necrosis was gradually getting more severe.Infiltration of the inflammatory cells,granulation tissue formation and fibrous tissue restoration were noticed in peripheral ablation lesions.Rimlike enhancement and increased glucose metabolism appeared surrounding the lesions on CT and PET-CT,especially in the 1st to 2nd week groups.For the 8 th week group after RFA,the enhancement or hypermetabolism metioned above disappeared when perilesional tissue regeneration became more obvious.From the dynamic curve of changes on enhanced CT,marked enhancement occurred in the immediate group after ablation(r_(p/p)=1.34±0.21),reached its peak at the 1st week group(r_(p/p)=1.39±0.20),and then declined gradually.The metabolic changes on PET-CT showed a typical single peak curve,with the peak at the 1st week group(r_(p/p)=1.19±0.09)and similar even metabolism at the immediate and 8 th week group.Conclusions Both CT and PET-CT imaging can well correlate with the histopathological changes after RFA in the normal liver.To avoid the interference of inflammatory reaction when differentiating normal liver tissue from residual tumor,it is better to take radiology examination immediately and 8 weeks after RFA.PET-CT probably has advantages over CT immediately after RAF.After 1 week,PET-CT and CT may have similar diagnostic efficacy.