J. Louis Hinshaw MD, Presenter: Stockholder, NeuWave Medical Inc Medical Advisory Board, NeuWave Medical Inc Stockholder, Cellectar Biosciences, Inc

1) Understand the expected imaging findings after image-guided tumor ablation. 2) Understand the typical findings of complications, local tumor progression, and disease progression. 3) Learn about newer imaging modalities/methods for identifying local tumor progression.

Image-guided tumor ablation is a rapidly advancing minimally invasive targeted therapy for the treatment of both malignant and benign tumors. Even if you are not actively involved in performing this procedure, you will almost certainly see follow-up imaging performed to evaluate for both local tumor progression and metastatic disease. Following this discussion, you should have a basic understanding of the typical indications for image-guided tumor ablation and the imaging findings associated with normal evolution of the ablation zone as well as findings suspicious for recurrent disease. Of course, this varies depending on the target organ/disease, as well as the underlying malignancy. For example, colorectal carcinoma metastatic to the liver tends to be relatively hypovascular and similar in attenuation to the avascular ablation zone on portal venous phase imaging. Therefore, the primary indicator of recurrence in this clinical setting is asymmetric change/growth one or more of the ablative margins. In contrast, hepatocellular carcinoma is most frequently hypervascular. Since the ablation zone should be avascular, any evidence of vascular enhancement within/around the ablation zone on follow up imaging can be suspicious for residual or recurrent disease. The imaging findings also vary depending upon the ablation modality utilized, particularly when MRI is used for the imaging follow up and we will go through the signal changes that occur over time following an ablation. In addition, we will discuss standardized nomenclature to describe the follow up imaging for tumor ablation. Although the nomenclature is descriptive and extremely helpful, particularly to ensure consistency and improve reporting for research purposes, the terms are not always intuitive.

Hinshaw, J, Surveillance Imaging Following Focal Ablative Therapies (Microwave, Radio-frequency Ablation, Cryoablation).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019818.html