[F-18] fluorodeoxyglucose positron emission tomography as a tool for early recognition of incomplete tumor destruction after radiofrequency ablation for liver metastases.

BACKGROUND AND OBJECTIVES

To assess the value of FDG positron emission tomography (PET) for early detection of incomplete tumor destruction after radiofrequency ablation (RFA) for liver metastasis.

METHODS

Twenty-eight unresectable liver metastases in 17 patients were treated by RFA. Patients underwent computed tomography (CT) and FDG-PET preoperatively, at 1 week, 1 month, and 3 months postoperatively. Postoperative CT and FDG-PET at 1 week and 1 month were analyzed to identify hypervascular and hypermetabolic residual tumors at the RFA site. These results were correlated with follow-up CT and, in case of reintervention, with pathologic results.

RESULTS

In 24/28 of RFA-treated metastases, CT and FDG-PET at 1 week and 1 month showed no tumor residues. During follow-up, none of these 13 patients developed local recurrence at RFA site. In four patients, FDG-PET at 1 week and 1 month showed peripheral hypermetabolic residue after RFA, whereas CT did not revealed residual tumor. In three patients, local persistence of viable tumor cells was biopsy-proven at reintervention. In the fourth, follow-up CT showed subsequent development of a local recurrence.

CONCLUSIONS

FDG-PET accurately monitors the local efficacy of RFA for treatment of liver metastases, as it early recognizes incomplete tumor ablation, not detectable on CT.