Hepatic tumors treated by cryosurgery: normal CT appearance

An understanding of the normal appearance of hepatic tumors treated with cryosurgery is essential for accurately distinguishing normal postoperative changes from potential complications such as hepatic abscess or infarct, which may necessitate further interventions. The purpose of this study was to characterize the normal spectrum of CT findings after cryoablation of hepatic tumors.

The CT scans of 14 patients who had undergone hepatic cryoablation 4-16 days (mean, 7 days) before scanning were reviewed by three radiologists. None of these patients had postprocedural complications that necessitated intervention (e.g. abscess, infarct, or hemorrhage). Indications for cryoablation included primary hepatic tumors in four patients and hepatic metastases in 10 patients. CT findings were correlated with surgical findings in a lesion-by-lesion manner to ensure that only cryolesions were included in the analysis.

Twenty-eight cryolesions from 3 to 11 cm maximum diameter (mean, 7 cm) were detected on CT scans. All cryolesions were primarily hypodense and extended to the liver capsule. Ten (36%) of 28 lesions contained air, and 26 (93%) of 28 lesions contained hemorrhage. Thirteen (54%) of 24 lesions evaluated with i.v. contrast material showed peripheral enhancement. Cryolesions were primarily wedge shaped (54%), round (29%), or teardrop shaped (21%). One iatrogenic portosystemic shunt was detected. Other associated findings included subcapsular hemorrhage (29%), perihepatic fluid collections (43%), right-sided pleural effusion (93%), left-sided pleural effusion (64%), atelectasis of one or both lungs (93%), and ascites (7%).

The postoperative CT appearance of the liver in patients who underwent hepatic cryoablation without complications mimics that seen in the liver of patients with hepatic abscesses or infarcts. The CT appearance of the liver in patients undergoing cryosurgery needs to be carefully analyzed to avoid confusing normal findings related to the procedure with those related to procedural complications, it may be impossible to differentiate hepatic complications from normal postoperative changes on the basis of CT findings in many of these patients.