ARRS 2022 Abstracts

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E2018. Hot or Cold: A Guide to Locoregional Thermal Ablation
Authors
  1. Marc Fromherz; Carilion Roanoke Memorial Hospital
  2. Brandon Rodgers; The Ohio State University Wexner Medical Center
  3. Robert Moranville ; The Ohio State University Wexner Medical Center
  4. Michael Cline; The Ohio State University Wexner Medical Center
  5. Mina Makary; The Ohio State University Wexner Medical Center
Background
Locoregional thermal ablation therapy has become an increasingly viable treatment option for patients with malignant or benign lesions in a variety of body systems. Under image-guidance, these minimally invasive procedures have proven to be therapeutic in patients with contraindications to surgery, as a bridge therapy to surgery or transplantation, and as a means to provide symptomatic relief. As the popularity of minimally invasive ablation techniques grow, it is increasingly important to understand the different modalities used and when one technique may be favored over another. To make an informed decision, an interventional radiologist must understand the physics behind each technique, the physiologic properties of the target tissue, and how these concepts interact in the setting of thermal ablation. In this guide, the techniques of microwave ablation, radiofrequency ablation, and cryoablation will be examined.

Educational Goals / Teaching Points
After viewing this guide, learners will be able to recognize the different thermal ablation modalities, understand the physics by which they achieve cytotoxicity, and understand how the properties of different body tissues can augment their effectiveness. Current evidence-based guidelines will be reviewed for various pathologies for the learner to understand how they have been established based on the relative advantages and disadvantages of each modality. They will also be able to identify future innovative techniques and applications of these modalities.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Having a comprehensive understanding of anatomy is critical when performing thermal ablation procedures. It allows for the proper identification of the target organ, the lesion within that organ, as well as important adjacent structures near the target. The physiologic properties of the tissue have varying effects based on the chosen technique, as aerated lung is a poor conductor making radiofrequency less effective, and a cirrhotic liver prone to bleeding increases the risk of shock with cryoablation. Contrast-enhanced CT and MRI images are used to analyze the anatomy prior to deciding on an ablation technique, and again to assess treatment outcome and monitor for recurrence. In this guide, the importance of anatomy and tissue physiology in thermal ablation will be discussed, and examples of CT and MRI will be used to showcase the radiologic findings of each modality.

Conclusion
Locoregional thermal ablation is a key weapon in the interventional radiologist’s arsenal against cancer. Although the ultimate goal of tumor cell necrosis may be the same across all techniques, the mechanisms by which these techniques achieve their goal vary. Understanding the physics of these mechanisms and how they interact with body tissue can help an interventional radiologist choose the technique best suited for his or her patient’s presentation. This exhibit aims to provide a basic understanding of the mechanisms behind different thermal ablation techniques, the clinical situations that favor one technique over the other, and the current clinical outcome evidence for locoregional ablation therapy.