SIR 2024
Interventional Oncology
John Barrera, MD
Resident Physician
Unviersity of Virginia
Financial relationships: Full list of relationships is listed on the CME information page.
Luke R. Wilkins, MD, FSIR
Associate Professor
University of Virginia
Financial relationships: Full list of relationships is listed on the CME information page.
1. Review typical image-guided approach for percutaneous liver ablation.
2. Techniques for occult lesion localization: contrast enhanced ultrasound (CEUS), pre-operative ethiodized oil transarterial embolization (TACE), direct sub-selective hepatic arteriography, and on-table multiphase CT with fusion imaging.
3. Advantages and disadvantages of each technique and tips and tricks for success.
Background:
Primary and secondary malignant hepatic lesions require a multidisciplinary treatment approach. Percutaneous ablation is a potentially curative treatment option for many liver cancers. A combination of ultrasound (US) and noncontrast CT / CT-fluoroscopy are the primary imaging modalities utilized for ablation probe placement. However, many lesions are not visualized with these modalities. Strategies for alternate lesion visualization include CEUS, pre-operative ethiodized oil TACE2, direct hepatic artery angiography with fusion imaging 3-4, and on table multiphase CT.
Clinical Findings/Procedure Details:
CEUS utilizes microbubbles for lesion localization. CEUS is a low cost, accessible, radiation-free technique for probe placement from a variety of trajectories. However, enhancement is transient as the microbubbles pass through the hepatic circulation, potentially requiring repeat injections and obscuring imaging after initial enhancement. Additionally, not all lesions can be visualized with ultrasound.
Ethiodized oil arterial chemoembolization has been utilized for many years as locoregional treatment for hepatocellular carcinoma. The ethiodized oil contrast medium is retained in malignant hepatocytes long after embolization and can be injected pre-procedurally. During ablation the lesion can be localized under CT. Although effective, this approach requires additional procedures and associated risks.
Direct hepatic artery angiography can be performed before hepatic ablation and provides accurate localization of arterial enhancing lesions. Injections can be performed during real time CT-fluoro in hybrid angiosuites or fusion images can be created for ablation probe placement. Similarly, multiphase (arterial, venous, delayed phase) on table imaging can be performed via peripheral IV with creation of fusion imaging during or after probe placement.
Alternatively, regional anatomic landmarks can be utilized to place the ablation probe.
Conclusion and/or Teaching Points:
Imaging advances now offer a variety of techniques for localizing hepatic lesions that are occult on noncontrast US/CT. These techniques expand the subset of lesions amenable to percutaneous hepatic ablation.