Ultrasound monitored hepatic cryosurgery: longevity study on an animal model.

Ultrasound imaging has been proposed to monitor the amount of frozen tissue during hepatic cryosurgery of primary and metastatic tumors. In this follow-up study, a cryolesion was produced in an adult pig under ultrasound monitoring. The animal was allowed to recuperate for 3 days before being sacrificed. Pathologic and histologic evaluation showed extremely close correlation with the ultrasound image. The necrotic region was clearly observable in the sonogram after 3 days. Ultrasonography can accurately represent the extent of the cryolesion both during as well as following cryosurgery.