kwartalnik polskiego towarzystwa ultrasonograficznego

Characterization of focal liver lesions
in non-cirrhotic liver
Dietrich C.F. 1 , Jędrzejczyk M. 2
1. innere Medizin 2, caritas-krankenhaus, Bad Mergenthein
2. Department of Diagnostic imaging, 2 nd Medical faculty of Warsaw Medical University
Correspondence:
Prof. Dr. med. christoph f. Dietrich
innere Medizin 2
Uhlandstr. 7, D-97980 Bad Mergentheim
telefon: 07931 / 58 2201, fax: 07931 / 58 2290
E-mail: christoph.dietrich@ckbm.de
Summary
focal liver lesions are characterised sonographically not only by analysis of differences in echogenicity
from the surrounding liver tissue, but also by the enhancement pattern of contrast media. as a result of
the double blood supply of the liver via both the portal vein and the hepatic artery, focal lesions in the
liver often exhibit no sustained hyper- or hypo perfusion, but depending on the perfusion phase and the
histology, present with a complex spatio-temporal picture of increased and reduced contrast enhancement.
conventional B-scan ultrasound makes it possible to characterize the frequently occurring typical
liver cysts and calcifications by differences in echogenicity in comparison with the surrounding liver
tissue. the characterisation of focal liver lesions by conventional B-mode ultrasound and colour Doppler
imaging in an otherwise healthy person is sufficient in typical cases (about 70 %). contrast enhanced
ultrasound (cEUs) has markedly improved the characterisation of liver lesions. certain lesions display
a characteristic contrast enhancement pattern (e.g., wheel-spoke phenomenon of focal nodular hyperplasia
[fnH]) or a distinctive perfusion pattern (e.g., iris diaphragm phenomenon [Haemangioma]),
allowing the lesions to be characterised.
Key words
focal liver lesions, contrast enhanced ultrasound
Introduction
the EfsUMB-guidelines and recommendations 2008
provide general advices for the use of Ucas to improve
the management of patients. the initial EfsUMBguidelines
have been published in 2004 and have been
further discussed in other papers. individual patients
must be managed in an individual fashion, therefore the
present article and illustrations of focal liver lesions in
the non-cirrhotic liver are intended to help in the decision
making process. focal liver diseases have evolved
into the single most important application of cEUs.
this technique now equals contrast enhanced computed
tomography (cEct) and in some instances exceeds
it in accuracy. Due to the dual blood supply of liver tissue
by the hepatic artery (25-30 %) and the portal vein
(70-75 %), three overlapping vascular phases can be
defined and visualized using contrast enhanced ultrasound
which is helpful for liver tumour characterisation.
18 ULTRASONOGRAFIA nr 34, 2008
Differentiation of benign and malignant liver lesions
Characterisation of a liver lesion starts once an
abnormality is found. an imaging procedure that is used
to detect liver masses should also enable the examiner
to differentiate between benign and malignant lesions,
since benign and malignant lesions have been reported
to vary in their uptake during the portal venous phase
[(1;2)]. the non-enhancing nature of malignant liver
lesions is explained by the lack of liver specific tissue,
e.g. portal veins, sinusoids and reticulo-endothelial cells
[figure 1]. contrast enhanced ultrasound may discriminate
between benign liver specific tissue and non-liver
specific tissue-mainly malignant focal liver lesions in
the portal venous and liver specific late phase in almost
all patients [table 1-3] [(1)] if cysts and calcifications
are excluded by conventional B-mode ultrasound. only