Diagnostic follow-up imaging: "Achilles heel" of performing radiofrequency heat ablation in lung malignancies

Purpose: To report on the successful radiofrequency heat ablation (RFA) in a patient with a bronchiogenic carcinoma verified by a combined imaging modality using computed tomography (CT) and 18-fluorodeoxyglucose (¹⁸FDG)- positron emission tomography (PET) in a follow-up period of 6 months. Methods: RFA was the favored treatment option for the 2.3 x 2.3 cm large brochiogenic carcinoma located in the right upper lobe. For this purpose a thermal lesion was created using a 15-gauge LeVeen™ Needle Electrode with an array diameter of 3.0 cm. Follow-up CT scans were performed at 3 and 6 months after RFA. In order to exclude metabolically active residual tumor ¹⁸FDG-PET was obtained 6 months after RFA. Results: Follow-up CT scan 3 months after RFA showed a slight increase in diameter of the treated tumor, presumably due to dystelectasis, surrounding hematoma or inflammation and granulation tissue. In line with the CT scan 6 months after RFA, which revealed shrinkage of the treated lesion according to scar formation; additionally the metabolic activity seen in whole body ¹⁸FDG-PET was not suspicious for viable tumor. Conclusion: Functional imaging like ¹⁸FDG-PET seems to be an important adjunct to CT in the early detection of local tumor recurrence after RFA of lung malignancies.