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SIR 2026

Scientific Session

Interventional Oncology

Session: IO - Liver Ablation

132 - Hepatic Histotripsy After Contrast Enhanced Ultrasound; Evaluation in an in Vivo Swine Model

Monday, April 13, 2026
3:27 PM - 3:36 PM ET
Purpose: During hepatic histotripsy, diagnostic ultrasound is used to identify and target tumors. Techniques to facilitate targeting poorly echogenic tumors are needed. Contrast enhanced ultrasound (CEUS) is commonly used to increase the conspicuity of liver tumors, however, the safety and efficacy of performing histotripsy after the administration of ultrasound contrast, which effectively lowers the cavitation threshold of the tumor and surrounding liver, is unknown. The purpose of this study was to assess the safety and efficacy of hepatic histotripsy after CEUS in an in vivo porcine liver model.

Materials and Methods: Six healthy, acute, female swine (mean weight, 52.3kg) each underwent two histotripsy treatments (2.0 cm diameter) of the liver. Following a control histotripsy treatment in either the right or left liver, ultrasound contrast was administered intravenously. After a 10-minute washout period (the reported terminal half life), a second histotripsy treatment (post-CEUS) was performed on the contralateral lobe. Imaging (intra- and post-procedural) and gross necropsy were used to assess off target damage to determine safety. Efficacy was assessed by comparing planned and actual treatment zone dimensions on post-treatment MRI and by confirming cell death on histology. Confidence intervals (p=0.05) were used to compare differences in treatment zone sizes between control and post-CEUS.

Results: 12/12 treatments were well demarcated and visible on post-treatment CEUS and MRI. No off-target cavitation was noted during treatment and there was no off-target damage on necropsy. One post-CEUS treatment was associated with mild T2 hyperintensity in the abdominal wall adjacent to the treatment zone without an identifiable pathologic correlate. Small portal or hepatic thromboses were observed in 5/6 post-CEUS and 6/6 control treatments. The average difference (95% CI) between planned and actual dimensions of the treatment zone was 8.1mm (5.3,10.8), 6.4mm (1.6,11.2), and 7.7mm (0.9,14.4) for the post-CEUS treatments and 10.1mm (6.0,14.2), 6.0mm (-0.3,12.2), and 8.1mm (6.4,9.9) for control treatments. Complete cellular destruction was achieved within all histotripsy treatment zones.

Conclusion: In this in vivo swine model, hepatic histotripsy after CEUS was safe and effective, provided a 10-minute washout period is included before energy delivery.