739 - Decoding Post-Ablative Imaging in the Lung: Endpoints, Follow-up Protocol, Recurrence and Complication Recognition After Image-Guided Ablation

Learning Objectives: - Review indications and contraindications for image-guided thermal ablation (IGTA), including potential sensitive areas
- Provide imaging follow-up protocols, timing and rationale
- Demonstrate spectrum of expected imaging findings related to IGTA lung parenchyma (intraprocedural, immediate, short-term follow-up, long-term)
- Compare and contrast imaging findings for microwave and cryoablation
- Review imaging pearls and pitfalls in detection of recurrence and complications related to IGTA

Background: Pulmonary ablation of primary and secondary ablation continues to gain broader acceptance in treatment of primary and secondary lung cancer due to therapeutic advantages related to morbidity, patient experience, cost, and, in particular, preservation of lung function. Both cryoablation and microwave ablation can produce imaging findings that can be challenging for the novice to interpret. These imaging findings change over the evolution of the ablation, from intra-operative, short-term and longer term. Post-IGTA in the lung, distinguishing findings related to inflammatory healing versus malignant progression can be nontrivial for the uninitiated. This exhibit aims to provide a working knowledge of the appropriate imaging timing, mechanisms leading to imaging findings, and the ability distinguish response to treatment across imaging modalities for IGTA.

Clinical Findings/Procedure Details: Patients with non-central lung tumors < 3 cm may be suitable candidates for IGTA. Procedure performance relies on CT imaging, not only for appropriate ablation probe placement but for predicting and monitoring ablation progression. Key expected findings from appropriately timed CT fluoroscopy and/or short helical scans during both cryoablation and microwave ablation procedure provide insight to ablation zone progress (e.g. appearance of microhemorrhage/iceball; ground glass with microwave ablation). Follow-up imaging protocols from chest x-rays in recovery and at 1 week, and the evolution of findings on provided suggested follow-up protocol of alternating unenhanced/enhanced CT and PET scans every 3 to 4 months is provided.

Conclusion and/or Teaching Points: Post-ablative imaging in the lung generally follows a predictable evolution. Knowledge of proper timing, protocols and associated findings is essential for building and supporting a lung ablation program.