Intraoperative monitoring and postoperative imaging of hepatic cryosurgery.

Because intraoperative sonography displays segmental anatomy, allows discovery of more lesions than previously suspected from preoperative imaging, surgical inspection, or palpation, and permits more certain diagnosis of problematic masses, it facilitates surgical decision-making when liver resection or cryoablation is anticipated. Intraoperative sonography provides a guidance modality to accurately place cryosurgery probes in liver masses. More precise treatment of metastatic and primary tumors of the liver is possible with cryoablation because intraoperative sonography provides a means of monitoring the growth of the enlarging freeze zone to insure adequate surgical margins. Postoperative detection of acute complications after cryosurgery is best done with computed tomography. Normally cryosurgery defects shrink with time and lose the peripheral contrast opacification seen after surgery. Gas collections, seen as a result of tissue necrosis, must be discriminated from infection. Tumor recurrence can be detected well with computed tomography or magnetic resonance imaging following hepatic cryosurgery.