Assessment of Radiofrequency Ablation of Lung Metastasis From Colorectal Cancer Using Dual Time-Point PET/CT

Department of Nuclear Medicine, Hospital Clínic, Barcelona, Spain.
Clinical nuclear medicine (Impact Factor: 3.93). 07/2011; 36(7):603-5. DOI: 10.1097/RLU.0b013e318217741b
Source: PubMed


A 70-year-old man with operated colorectal cancer relapsed with a solitary lung metastasis. Dual time-point PET/CT performed at 60' (standard images) and after 2 hours (delayed images) showed focal uptake in the lung nodule. A second uptake in the liver dome was also visualized only in the delayed images. Radiofrequency of the lung metastasis was performed by CT-fluoroscopy guide. A PET/CT 1 month after radiofrequency showed significant reduction of activity in the delayed images, and the uptake at 3 months was virtually normal. A fine-needle biopsy of the liver lesion confirmed the final diagnosis of metastasis from adenocarcinoma.

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    ABSTRACT: Although they have proven effectiveness, radiofrequency and microwave ablation techniques have a high rate of partial responses. Diagnostic studies that anticipate the changes in morphology are essential for earlier detection of residual viable tumor tissue or local recurrences to identify patients who will benefit from a new treatment. Our study has determined the diagnostic yield of PET/CT studies at baseline and follow-up and adequate time between them and the ablation intervention. Seven patients with single tumor lesion with a total of 8 ablations were included. CT and PET/CT studies were performed at baseline and follow-up after ablation. Average times between PET studies at baseline and follow-up and the ablative therapy were 1.8 and 3.4 months, respectively. Mean scores in metabolic activities of the PET at baseline and follow-up were 7.6 and 4.3g/ml of SUVmax, respectively. The Dual Time Point technique helped to identify viable tissue after ablation in 3 cases. Follow-up PET/CT studies have conditioned the various treatment strategies adopted by clinical oncologists. The high yield of the PET/CT study including the Dual Time Point technique may be considered as a study replacement of initial and follow-up Contrast-Enhanced CT before and after treatment with RFA and AMO, this achieving considerable reduction in the exposure to high radiation levels. We propose conducting the first PET/CT follow-up study at 3 months of the RFA and AMO.
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