Cryoablation
Cryotherapy is a controlled destruction of tissue by freezing. Due to the excellent visualization of the ice ball on imaging and the close correlation between the ice ball and the zone of necrosis, this is a very precise ablation modality. In addition, mu
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Cryoablation Meghan G. Lubner, J. Louis Hinshaw, Chris L. Brace, and Fred T. Lee, Jr.
Abstract
Cryotherapy is a controlled destruction of tissue by freezing. Due to the excellent visualization of the ice ball on imaging and the close correlation between the ice ball and the zone of necrosis, this is a very precise ablation modality. In addition, multiple probes can be used to generate larger ablation zones, and probes can be controlled individually allowing some sculpting of the ice ball. Cryotherapy may be less sensitive to “cold sink” effects. However, cryoablation lacks the natural cautery effect of heat-based modalities, may be more time consuming and expensive than radiofrequency ablation, and has risk for cryoshock with large volume ablations. In this chapter, we will review the indications, technique, and management of patients undergoing cryoablation.
Introduction Controlled destruction of tissue by freezing is widely practiced for a variety of purposes ranging from treatment of dermatologic lesions to
M.G. Lubner (*) J.L. Hinshaw Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA e-mail: [email protected]; [email protected] C.L. Brace Department of Radiology, University of Wisconsin – Madison, Madison, WI, USA e-mail: [email protected] F.T. Lee, Jr. Department of Radiology, University of Wisconsin, Madison, WI, USA e-mail: [email protected]
ablation of tumors. Cryoablation is one of the oldest available tumor ablation modalities, with its origins in the 1800s when advanced carcinomas of the breast and cervix were treated with iced saline solutions [1, 2]. The last 50 years have seen great advances in the knowledge of the biological effects of freezing and the introduction of new technology. The purpose of this chapter is to review the principles, technique, applications, advantages, and complications of cryoablation.
Principles of Cryotherapy Tissue freezing during cryoablation causes both intracellular and extracellular formation of ice. The mechanism of cell death varies with the rate
D.E. Dupuy et al. (eds.), Image-Guided Cancer Therapy, DOI 10.1007/978-1-4419-0751-6_6, # Springer Science+Business Media New York 2013
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and final temperature of freezing. Freezing at faster rates and to lower temperatures leads to formation of intracellular ice crystals. Intracellular ice crystals cause direct damage to the cell membrane and organelles producing cell death. Slower rates of freezing produce extracellular ice crystals, which leaves the rest of the extracellular milieu hyperosmolar to the intracellular compartment. This leads to cell dehydration and death [1, 3]. The critical cell kill temperature at which cells are irreversibly destroyed varies with cell and tissue type, ranging from approximately 20 C for water-rich tissues [4, 5] to 40 C for more fibrous tissues [5, 6]. Cryoprobes freeze tissue via circulation of a cryogen in a closed system. Early cryoprobes used liquid nitrogen as a cryogen. Early nitrogen systems demonstrat
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