The effects of cancer chemotherapy on liver imaging.

Chemotherapy changes the appearance of liver tumours and may also affect the liver parenchyma. Tumours respond with changes in size, outline, and internal architecture. The accuracy of liver CT for detecting metastases is reduced after chemotherapy. Histologic studies have shown that some metastases which become invisible on follow-up CT are completely sterile at later resection, but most 'disappearing' lesions still contain active tumour. Hepatic steatosis becomes much more common after chemotherapy. Diffuse fatty change may conceal metastases on US and CT, whilst focal steatosis may mimic tumour. Chemical-shift MRI will distinguish fat from tumour. Fatty change is usually reversible, unless the liver receives a 'second hit' of damage from other causes. Sinusoidal obstructive syndrome (SOS), nodular regenerative hyperplasia, veno-occlusive disease and peliosis are manifestations of microvascular injury which can result from chemotherapy. SOS, the most common of these, is undetectable on US and CT, but can be shown on SPIO-enhanced MRI. Although SOS causes no symptoms in most patients, it may cause increased bleeding from the friable liver at surgery, and greater risk of peri-operative adverse events. Rarer complications of chemotherapy include pseudo-cirrhosis and sclerosing cholangitis.