Clinical Application Of Early PET/CT Imaging After Radiofrequency Ablation Of Hepatic Malignancies

ObjectiveTo discuss the application of early ¹⁸F-FDG PET/CT imaging after radiofrequency ablation of hepatic malignancies.Materials and MethodsFifteen patients undergoing RFA as part of clinical management,each for a single liver tumor(five hepatocellular carcinoma,ten colorectal cancer liver metastasis).The ablation lesions all were hypermetabolic on PET/CT performed within 2 weeks before RFA.Study subjects underwent 18F-FDG PET/CT(early PET/CT) within 24 hours after RFA.Total photopenia,focal uptake,and rim-shaped uptake were regarded as complete ablation,residual tumor,and inflammation,respectively.Patients underwent follow-up PET/CT scans served as the reference standard.ResultsTwelve patients had findings of total photopenia at the ablation site on the early PET/CT scan,and in all of these patients,total photopenia at the ablation site was seen on the follow-up PET/CT scan;Two patients had focal uptake at the ablation site on the early PET/CT scan,both of these foci increased in size and intensity,which is compatible with residual tumor at the time of ablation;Only one patient had rim-shaped uptake on the early PET/CT scan.The rim-shaped uptake had disappeared on PET/CT performed 3 months after RFA,which was result from inflammatory.The total diagnosis accordance rate was 100%,and 93.3%(14/15)patients had no inflammatory uptake on early PET/CT.ConclusionIn conclusion,there is infrequent inflammatory uptake at the RFA site of liver tumors on ¹⁸F-FDG PET/CT if scanning is performed within 24 hours after ablation.Thus,we conclude that early PET/CT has the potential to evaluate the efficacy of an RFA procedure by indicating tumor-free as total photopenia and residual tumors as focal uptake.