Volumetric Arterial Enhancement Fraction Predicts Tumor Recurrence After Hepatic Radiofrequency Ablation of Liver Metastases: Initial Results

OBJECTIVE. The objective of our study was to investigate the diagnostic value of the volumetric arterial enhancement fraction of the liver with color mapping for the early detection of tumor relapse after hepatic radiofrequency ablation (RFA). MATERIALS AND METHODS. Fifty-three patients (24 men, 29 women; mean age +/- SD, 65 +/- 10 years) with a total of 215 liver metastases treated by RFA and a mean postinterventional follow-up period of 20 +/- 15 (SD) months were included in this retrospective study. Quantitative arterial enhancement fraction color maps of the whole liver were computed from triple-phase contrast-enhanced MDCT images. Follow-up examinations served as the standard of reference. The diagnostic performance of the arterial enhancement fraction color maps to predict subsequent tumor occurrence before tumor was visible on routine multiphase CT images was evaluated. RESULTS. The mean arterial enhancement fraction of segments that developed metastases (62% +/- 23%) was significantly higher than the mean of segments that did not develop metastases (39% +/- 20%) (p <0.0001). Receiver operating characteristic curve analysis revealed a probability of 77% for arterial enhancement fraction values to be higher in case of subsequent metastases as compared with liver parenchyma without tumor recurrence. CONCLUSION. The arterial enhancement fraction provides incremental value in the imaging surveillance for liver metastases after RFA. Arterial enhancement fraction color maps may be suited to predict tumor recurrence earlier than routine assessment using contrast-enhanced MDCT.