MR-guided percutaneous cryotherapy of the liver: in vivo evaluation with histologic correlation in an animal model

The purpose of this study was to evaluate the feasibility of MR-guided percutaneous cryotherapy of the porcine liver and to correlate the resulting tissue necrosis with MR imaging and histology. Using an MR-compatible, argon-based cryotherapy system (CryoHit; Galil Medical Ltd., Israel) with 2- and 3-mm diameter tapered cryotherapy probes, MR-guided percutaneous cryotherapy was performed in seven pigs (mean body weight, 40 kg) under general anesthesia in a short-bore magnet (1.5 T ACS NT; Philips, The Netherlands) using an ultrafast T2-weighted single-shot LoLo TSE sequence and a T1-weighted gradient-echo sequence. The frozen liver tissue was depicted accurately on fast T2- and T1-weighted sequences, providing precise delineation of the ablated tissue volume. On follow-up postcontrast MR controls, the cryolesions appeared avascular. They decreased in size compared with the initially frozen volume down to 70% at a 2-week follow-up. Histologically, a coagulation necrosis with a close correlation to the MR follow-up examinations was objectified. No cryotherapy-related complications occurred. J. Magn. Reson. Imaging 2001;13:50-56.