Figure 18c. CT evaluation of hepatic cryoablation. (a) Pretreatment CT scan shows a colorectal metastasis (arrow) in the dome of the liver that measures 3.5 cm. (b) CT scan obtained 4 days after cryoablation shows a low-attenuation cryolesion (arrow) measuring 5 x 6 cm completely encompassing the tumor site. Small gas bubbles are also seen, a finding indicative of necrosis. (c) Follow-up CT scan obtained 8 months after cryoablation shows the residual cryolesion (arrow) markedly decreased in size as a result of healing and fibrosis.