Ultrasonography is an extremely useful diagnostic tool in a patient with features suggestive of cholestatic jaundice.

The intrahepatic ducts are visualized only when dilated to a calibre of 4 mm or more. Extrahepatic ducts of normal calibre are seen in 60–80% of patients, but dilated extrahepatic ducts (6–8 mm is the normal range; <10 mm if there has been a previous cholecystectomy) are regularly seen. In extrahepatic obstruction dilation of the extrahepatic ducts precedes dilation of the intrahepatic ducts. In intrahepatic cholestasis the bile ducts are usually normal, but there may be some dilation of intrahepatic (but not of extrahepatic) ducts.

There are some drawbacks to ultrasonography. Common duct stones, sclerosing cholangitis and ampullary strictures may escape detection; the distal common bile duct is obscured by bowel gas in some patients; enlargement of the pancreatic head may be due to either carcinoma or chronic pancreatitis; and gallstones may be incidental findings unrelated to the cause of jaundice. Endosonography is especially useful for detecting bile duct stones and pancreatic carcinomas.

The normal liver receives 25% of its blood supply from the hepatic artery and 75% from the portal vein. In metastatic liver disease the arterial contribution increases. This can be measured by dynamic angiographic scanning after IV administration of ^99mTc-Iabelled tin or sulphur colloid with 2-s frames for a minute and a subsequent conventional series of static frames. A hepatic perfusion index is calculated of arterial versus venous flow, which is >0.4 in metastatic disease and less than this in normal controls. There is overlap in other diseases however.

A film of the abdomen is of help in determining the liver and spleen size. An enlarged liver frequently causes diaphragmatic elevation though an enlarged spleen does not. Calcification in the liver substance is seen in benign tumours particularly haemangiomas, and in malignant tumours, abscesses and hydatid cysts. Less than 50% of hepatic hydatid cysts show calcification which may appear as a thin rim over part or all of the cyst surface, or the cyst may be extensively calcified in a reticular pattern. Air may be seen in the biliary tract and the identification of gallstones may be useful in the icteric patient.

A barium swallow is of help in the identification of oesophageal varices, which are best demonstrated when the lower oesophagus is coated with a thin layer of barium. The oesophagus is slightly dilated and numerous filling defects distort the vertical mucosal folds. The presence of varices indicates the opening of portasystemic anastomotic channels and is a sign of portal hypertension. Varices are present when there is either intra- or extrahepatic obstruction to the portal circulation and do not necessarily indicate hepatitic cirrhosis. They may be seen in the acute fatty liver, infectious and alcoholic hepatitis, and presinusoidal causes of portal hypertension such as schistosomiasis.

This procedure provides good images of the liver and can demonstrate space-occupying lesions such as tumours, cysts and abscesses, as well as fatty liver. It is superior to isotope scanning and ultrasonic scanning. Results can be improved by use of lipiodol contrast. Spiral CT is better because it avoids misregistration problems from multiple breath holds.

MRI is superior to ultrasonography and isotope scanning in liver disease because of its greater sensitivity. It is also superior to CT, and is likely to become more so with further technical advances and the use of contrast media, such as gadolinium-DTPA and superparamagnetic ferrite-iron oxide particles.

Though safe, it cannot be used in the presence of significant amounts of ferromagnetic materials, which excludes many patients with implants and prostheses. The technique is noisy and claustrophobic, and cannot be tolerated by some patients, when CT in a torus scanner is an alternative.

Selective coeliac arteriography is of value in the investigation of patients with liver disease. The technique can be used to distinguish between benign lesions (such as hydatid cysts) and malignant tumours, which produce a characteristic distortion of the hepatic arterioles. The vasculature is also distorted in the cirrhotic liver. The technique can be used to outline the portal vein in patients who have undergone splenectomy or when splenic venography is contra-indicated. The tip of the catheter is placed in the orifice of the superior mesenteric artery and contrast agent injected while imaging rapidly. The technique presents few problems for the radiological department versed in angiographic techniques. Selective mesenteric arteriography has been used to define the collateral circulation in portal hypertension and to enable the direct infusion of pitressin to control haemorrhage. It is also used pre-operatively to assist planning of surgery.

Magnetic resonance arteriography is an attractive alternative procedure.

This highly specialised technique of vibration controlled transient ultrasonography measures stiffness of the liver, and particularly fibrosis, steatosis and cirrhosis. Increased values are also seen in congestive cardiac failure.

Normal readings are 2.5–7.5 kPa. These exclude cirrhosis and steatosis, and may make liver biopsy unnecessary, particularly in assessment of excess alcohol intake. In hepatitis C where no other problem is suspected, values >14 kPa indicate a 90% chance of cirrhosis.