title: Dual time-point (18)F-FDG PET/CT to assess response to radiofrequency ablation of lung metastases.
abstract: OBJECTIVE
  To establish the usefulness of dual time-point PET/CT imaging in determining the response to radiofrequency ablation (RFA) of solitary lung metastases from gastrointestinal cancer.
  
  
  METHODS
  This prospective study included 18 cases (3 female, 15 male, mean age 71±15 yrs) with solitary lung metastases from malignant digestive tract tumors candidates for RFA. PET/CT images 1h after injection of 4.07MBq/kg of (18)F-FDG (standard images) were performed at baseline, 1 month, and 3 months after RFA. PET/CT images 2h after injection centered in the thorax at 1 month after RFA were also performed (delayed images). A retention index (RI) of dual time-point images was calculated as follows: RI=(SUVmax delayed image-SUVmax standard image/SUVmax standard image)*100. Pathological confirmation of residual tumor by histology of the treated lesion was considered as local recurrence. A negative imaging follow-up was considered as complete response.
  
  
  RESULTS
  Local recurrence was found in 6/18 lesions, and complete response in the remaining 12. The mean percentage change in SUVmax at 1 month and at 3 months showed a sensitivity and specificity for PET/CT of 50% and 33%, and 67% and 92%, respectively. The RI at 1 month after RFA showed a sensitivity and specificity of 83% and 92%, respectively.
  
  
  CONCLUSIONS
  Dual time point PET/CT can predict the outcome at one month after RFA in lung metastases from digestive tract cancers. The RI can be used to indicate the need for further procedures to rule out persistent tumor due to incomplete RFA.
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.
authors: S
authors: S
authors: Lafuente
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain. Electronic address: dfuster@clinic.ub.es.
authors: D
authors: D
authors: Fuster
authors: Radiology Department, Hospital Clínic, Barcelona, Spain.
authors: P
authors: P
authors: Arguis
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.
authors: U
authors: U
authors: Granados
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.
authors: P
authors: P
authors: Perlaza
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.
authors: P
authors: P
authors: Paredes
authors: Radiology Department, Hospital Clínic, Barcelona, Spain.
authors: I
authors: I
authors: Vollmer
authors: Radiology Department, Hospital Clínic, Barcelona, Spain.
authors: M
authors: M
authors: Sánchez
authors: Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.
authors: F
authors: F
authors: Lomeña
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation; D005260:Female; D019788:Fluorodeoxyglucose F18; D005770:Gastrointestinal Neoplasms / Q000473:pathology; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Cáncer digestivo; Delayed images; Gastrointestinal cancer; Imágenes tardías; Lung metastases; Metástasis pulmonares; PET/CT; PET/TC; Radiofrecuencia; Radiofrequency