Lectures

Focal liver lesion: nonlinear contrast-enhanced ultrasound imaging

Enhancement Patterns of Benign Focal Lesions

Fatty Liver

Hepatic steatosis is due to decreased liver clearance of fatty acids It is caused by hepatocellular injury and increased production or mobilization of fatty acids. Alcohol, diabetes, obesity, and drugs are the most common etiologies. Fatty changes may present several morphologic and histological appearances according to diffuse or focal involvement. A pseudo-nodular pattern might lead to a questionable diagnosis particularly in oncologic patients. Also spared areas can show ambiguous US findings (Kroncke et al., 2000).

Focal fatty sparing

In diffuse fatty liver focal spared areas are frequently encountered; these are typically located along the liver hilum or around the gallbladder. On conventional US they appear as hypo-echoic areas with well-defined margins. Color Doppler does not reveal irregular vessels due to mass effect within the lesions. Contrast-enhanced ultrasound reveals typical vascular behavior similar to the surrounding parenchyma.

  • Typical features:
    • Arterial phase iso-enhancing;
    • Portal Vein phase: iso-enhancing;
    • Parenchymal phase: iso-enhancing.

Focal fatty change:

Focal areas of fatty infiltration can be found mimicking true focal lesions; on conventional US they appear as typically round-shaped hyper-echoic lesion. Color Doppler and CEUS findings are similar to those of fatty spared areas.

  • Typical features:
    • Arterial phase: iso-enhancing;
    • Portal Vein phase: iso-enhancing;
    • Parenchymal phase: iso-enhancing.

Case A-3.1

Rounding hypoechoic area in segment 5. In arterial phase normal distribution of the intralesion vessels structures. In portal and parenchymal phase it is found homogenous enhancement regarding the surrounding parenchyma. C.R: area of focal fatty sparing

Case A-3.2

Focal liver lesion in segment 1, solid hypoechoic. In early arterial phase and in portal phase it is found homogenous enhancement regarding the surrounding parenchyma. In early and late parenchymal phase it is not found pathological wash out. In late parenchymal phase light hyper-enhancement regarding the surrounding parenchyma. C.R: area of focal fatty sparing