Current aspects of multimodal ultrasound liver diagnostics using contrast-enhanced ultrasonography (CEUS), fat evaluation, fibrosis assessment, and perfusion analysis - An update

Abstract

Current ultrasound multifrequency probes allow both improved detail resolution and depth of penetration when examining the liver. Also, new developments in vascular diagnostics, elastography with fibrosis assessment, evaluation of possible steatosis, and parametric and time intensity curve (TIC) analysis of dynamic microvascularization of the liver with contrast-enhanced ultrasound sonography (CEUS) complement ultrasound-guided diagnostics. State-of-the-art high-resolution technology includes a high frame rate (HiFR) mode for CEUS, fast shear wave measurements with the sound touch quantify (STQ) mode, artifact-free flow detection using HR flow and glazing flow in combination with a special flow-adapted imaging (Ultra Micro Angiography, UMA) and additionally different assessments of possible fatty liver (UltraSound ATtenuation Imaging Technology, USAT). In 50 cases with focal liver lesions, a multimodal liver diagnosis was performed with a still new high-performance ultrasound system as part of the clarification of questions from the university liver consultation and tumor outpatient clinic.

Keywords: Contrast enhanced ultrasonography (CEUS); fibrosis; liver cancer; perfusion analysis.

Fig. 1

New ultrasound modalities of non-invasive evaluation of the liver stiffness in a case of F1 fibrosis up to 1.5 m/s (a), color-coded shear wave technique with high image quality (5 green stars) with blue and less yellow colors parts as a sign of less liver stiffness (b). Using the new liver tissue technologies the parenchymal comparison from kidney cortex and liver tissue is possible with values > 1,2 (HRI+) and values up to 0.7 dB/cm/MHz for the liver fatty measurements (USAT) (c). LTI measurements with values up to 3.8 after chronic inflammatory reaction (d). High image quality of 100% and 5 stars in all case (e).

Fig. 2

Evaluation the liver vascularization after liver transplantation (LTX). Using the UMA technology simultaneous color coded flow evaluation of the hepatic artery, portal vein and the liver veins is possible (a). The new flow modalities enables with high quality the simultaneous detection of the low flow of the liver veins up to high flow of the hepatic artery (b).

Fig. 3

A hypoechogenic solid lesion in the center of the liver (a). Using CEUS perfusion imaging by parametric false colors and TIC-Analysis detection of irregular tumor neo-vascularisation is possible (b). Considering the inhomogeneous liver tissue change this is typical for a hepatocellular carcinoma (LI-RADS V).

Fig. 4

Possibilities of parametric evaluation of dynamic CEUS by false colors of dynamic arterial microvascularization of the liver. By red color detection of early enhancement of vascular structures (a) and hyperenhancement of a tumor lesion by red, orange and yellow color maps, not detectable by the fundamental B-mode (b).

Fig. 5

CEUS perfusion imaging after complete treatments of malignant liver lesions by microwave ablation therapy (MWA). Parametric imaging using color maps could visualize the different perfusion parameters (AUC, PKI, WiAUC, AT) (a). TIC analysis shows not relevant enhancement in the center of the MWA defect (red) and continuous enhancement of the margin (yellow) and the liver tissue (blue) (b).

Fig. 6

High resolution CEUS, parametric color coded imaging and CEUS perfusion imaging (a) with color maps of different perfusion parameters (DS, SR, FIT, mTT) and time intensity curve in a case of Osler's disease (b). Dynamic evaluation of the capillary microvascularization shows capillary shunts with early enhancement after 12 s, short mean transit time (MTT) and strongly global enhancement evaluated by the time-intensity-curve (TIC) (c).

Fig. 7

Color coded parametric and time intensity curve analysis (TIC) of dynamic microvascularization of a benign liver lesion using HiFR CEUS. Typical for a focal nodular hyperplasia (FNH) is the continuous enhancement for the center to the margin with than similar contrast like the live tissue. Color maps could visualize different perfusion parameters (AUC, PKI, WiAUC, AT).