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PATHOLOGY OF THE LIVER AND PORTAL VENOUS SYSTEM
A
B
C
Figure 4.12 (A) Focal nodular hyperplasia in the left lobe (arrows), which is isoechoic with normal liver tissue. (B) Following administration of microbubble contrast agent, the FNH displays a ‘spoked-wheel’ pattern of vascular enhancement during the early arterial phase. (C) The same lesion seconds later, showing a central scar.
usually associated with previous biliary interventions, such as ERCP, sphincterotomy or stent placement (Fig. 4.14).
MALIGNANT FOCAL LIVER LESIONS
The ‘mass effect’ This term describes the effect of a focal mass, whether benign or malignant, on surrounding structures and is a useful diagnostic tool. It implies the lesion’s displacing or invasive nature, i.e. the displacement of vessels and/or invasion or distor-
tion of adjacent structures and tissues as a result of the increasing bulk of a lesion. This effect differentiates a true mass from an infiltrative process such as steatosis, or an artefact. Masses which are large and/or closely adjacent to a vessel demonstrate the effect more readily. The mass effect does not, of course, differentiate benign from malignant masses, or help in any way to characterize the mass. It is particularly useful when the mass is isoechoic compared with normal liver (Fig. 4.15). In such cases, the effect of the mass on adjacent structures may be the main clue to its presence.
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