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ANATOMY FOR DIAGNOSTIC IMAGING
preferable if the catheter tip is beyond the origin of the cystic artery to avoid injury to the gallbladder.
spared in diseases that occlude the main hepatic veins (e.g. the Budd-Chiari syndrome). As a result it may undergo hypertrophy which, if extensive, may itself obstruct the IVC.
Portal venography This may be achieved by many routes (see the section on the portal vein). Within the liver the left portal vein passes anteriorly before turning left, and oblique views are therefore necessary to view this part of the vein. Before it turns left, a recurrent branch passes to the right to the quadrate lobe. This must not be mistaken for a right portal vein if the actual right vein is obstructed. Hepatic venography This is achieved via the inferior vena cava (usually via a retrograde approach from the internal jugular vein in the neck) with catheterization of each of the three main hepatic veins in turn. The right vein may enter separately and the middle and left veins may be seen to unite as a common trunk. This retrograde approach may also be used to achieve radiographically directed hepatic venous pressure measurements or transjugular hepatic biopsy, and to create an artificial portosystemic shunt in patients with portal hypertension when a TIPS procedure (transjugular intrahepatic portosystemic shunt) is performed. Venous drainage of the caudate lobe Because part of the caudate lobe is drained by small veins that enter the inferior vena cava directly, this lobe may be
Fig. 5.30 The biliary system and its relations.
Hepatic scintigraphy On anterior views in hepatic scintigraphy, an indentation is seen in the inferior border of the liver at the site of the gallbladder and another at the site of the ligamentum teres. A photon-poor area is seen above the latter at the attachment of the falciform ligament. A defect is seen superiorly at the site of the entry of the hepatic veins into the IVC, and another centrally at the porta hepatis. Superimposition of the breast and of the bowel (especially after barium studies) can cause false defects. On lateral views the liver is seen as elliptical, with the renal fossa posteriorly and the gallbladder fossa anteriorly, and a central defect for the porta hepatis. THE BILIARY SYSTEM (Figs 5.30 and 5.31)
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The gallbladder The gallbladder is a pear-shaped sac attached to the extrahepatic bile ducts by the cystic duct. It is very variable in size but normally measures up to 10 cm in length and 3 cm in diameter. It is described as having a fundus, body and neck, and it hangs on its bed on the visceral surface of the liver with its neck lying superiorly and its fundus inferiorly A pouch called Hartmann's pouch on the ventral surface just proximal to the neck is seen when the
