Contrast-Enhanced Ultrasound-Guided Liver Ablation for Obscure or Difficult Lesions: Case Examples and Review

Purpose: Contrast-enhanced ultrasound (CEUS) allows for real-time visualization and improved detection of enhancing liver tumors. We describe our experience with this technique in microwave ablation procedures as a problem-solving method for difficult to target, missed, or recurrent liver tumors.

Materials and Methods: As part of an ongoing observational study, we retrospectively reviewed the medical records of patients who underwent ablation of hepatocellular carcinoma (HCC) or liver metastases not well visualized on conventional ultrasound or computed tomography (CT) and requiring CEUS guidance, from 2017 to 2019. Imaging characteristics, technical success, and clinical response were assessed.

Results: We identified 4 patients (3 males; mean age, 68 years; standard deviation, 4 years) with obscure masses requiring CEUS guidance for ablation (3 HCC, 1 metastatic colorectal cancer). The purpose of CEUS use were as follows: (1) partial response within a heterogeneous liver tumor previously treated with transarterial chemoembolization, (2) tumor recurrence adjacent to a prior ablation (years prior) (3) persistent tumor adjacent to the previous ablation site (missed ablation weeks prior) in a multinodular liver, and (4) nonvisualized tumor on ultrasound and noncontrast CT in a patient with chronic kidney disease unable to receive intravenous CT contrast. All tumors demonstrated a complete response by Modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria with a median follow-up time of 9 months (range, 4–17 months).

Conclusions: CEUS is a useful adjunctive technique for guiding ablation in settings when CT or US guidance alone is unsuccessful or insufficient to completely characterize targeted liver tumors. Viewers of this exhibit will appreciate cases in which CEUS would serve as an appropriate supplement and promote future success in challenging liver tumor ablation cases.