Is Gadoxetate Disodium-Enhanced MRI Useful for Detecting Local Recurrence of Hepatocellular Carcinoma After Radiofrequency Ablation Therapy?

OBJECTIVE. The purpose of our study was to determine whether gadoxetate disodium-enhanced MRI improves the detection of locally recurrent hepatocellular carcinoma (HCC) after radiofrequency ablation therapy. MATERIALS AND METHODS. Forty-two consecutive patients (26 men and 16 women; mean age, 70.9 years) who had undergone radiofrequency ablation therapy for HCC were examined by gadoxetate disodium-enhanced MRI. Three independent radiologists reviewed two sets of MR images separately. Set 1 contained unenhanced T1-weighted, T2-weighted, and contrast-enhanced extracellular phase images, and set 2 contained unenhanced T1-weighted, T2-weighted, and contrast-enhanced extracellular and hepatocyte phase images. Diagnostic accuracies were determined by receiver operating characteristic (ROC) curve analysis. RESULTS. Of the 61 ablated lesions included, 10 developed local recurrence and 51 did not. Sensitivity (60-80% and 70-80% for sets 1 and 2, respectively), specificity (90-98% and 92-100%), and accuracy (87-95% and 89-97%) were not improved by adding hepatocyte phase images. Rather, mean area under the ROC curve (AUC) significantly decreased from 0.94 for set 1 to 0.82 for set 2 (p = 0.046), and the AUC of the radiologist with the least experience significantly decreased from 0.91 to 0.75 (p = 0.037). CONCLUSION. For gadoxetate disodium-enhanced MRI, the detection of local recurrence of HCC after radiofrequency ablation therapy was not found to be improved by including hepatocyte phase images. Furthermore, detection may be further impaired when a less-experienced radiologist interprets the images.