Comparison of computed tomography (CT) and contrast-enhanced ultrasound (CEUS) for the quantitative evaluation of an ablation defect following radiofrequency ablation of malignant liver lesions

OBJECTIVE: To compare contrast-enhanced computed tomography (CT) and contrast-enhanced ultrasound (CEUS) for the quantitative evaluation of an ablation defect following radiofrequency ablation of malignant liver lesions in a prospective study. MATERIALS AND METHODS: 22 radiofrequency ablations of malignant liver tumors were performed. The ablation defects were then measured and evaluated by two independent examiners via contrast-enhanced computed tomography (CT) and contrast-enhanced ultrasound (CEUS) using a 1-5MHz multifrequency convex ultrasound transducer (LOGIQ E9, GE) with respect to the short-axis diameter, the long-axis diameter, and the area. RESULTS: Quantitative evaluation of ablation defects is possible with both contrast-enhanced CT and CEUS. The average long-axis diameter was 47.1mm (+/- 11.08; +/- 23,5%) on CEUS and 56.48mm (+/- 14.14; +/- 25,0%) on CT; the short-axis diameterwas 39.72mm(+/- 11.14; +/- 28,05%) on CEUS and 40.27mm(+/- 10.50; +/- 26,07%) on CT; the areawas 1439.82 mm(2) (+/- 678.57; +/- 47,13%) on CEUS and 2392.68 mm(2) (1147.67; +/- 48,0%) on CT. On average, ablation defects are assessed to be larger on CT than on CEUS. A significant correlation between the modalities could not be achieved for all measurement axes. CONCLUSION: CEUS can be used for the postinterventional detection and evaluation of ablation defects. However, these are always assessed to be larger on contrast-enhanced CT than CEUS.