Irreversible Electroporation Ablation of Malignant Hepatic Tumors: Subacute and Follow-up CT Appearance of Ablation Zones

PurposeTo describe findings on contrast-enhanced computed tomography (CT) images of malignant hepatic tumors 24–72 hours after percutaneous ablation by irreversible electroporation (IRE) and at midterm follow-up.Materials and MethodsRetrospective analysis of 52 malignant liver tumors—30 primary hepatic tumors and 22 hepatic metastases—in 34 patients (28 men and 6 women, mean age 64 y) treated by IRE ablation was performed. Ablation zones were evaluated by two examiners in a consensus reading by means of a dual-phase CT scan (consisting of a hepatic arterial and portal venous phase) performed 24–72 hours after IRE ablation and at follow-up.ResultsDuring the portal venous phase, ablation zones either were homogeneously hypoattenuating (n = 36) or contained heterogeneously isoattenuating or hyperattenuating (n = 16) foci, or both, in a hypoattenuating area. Of 52 lesions, 38 included gas pockets. Peripheral contrast enhancement of the ablation defect was evident in 23 tumors during the arterial phase and in 36 tumors during the portal venous phase. Four tumors showed intralesional abscesses after the intervention. At follow-up (mean, 4.7 mo), the mean volume of the ablation defects was reduced to 29% of their initial value.ConclusionsBecause normal findings on contrast-enhanced CT images after IRE ablation may be very similar to the typical characteristics of potential complications following ablation, such as liver abscesses, CT scans must be carefully analyzed to distinguish normal results after intervention from complications requiring further treatment.