EUS liver assessment using contrast agents and elastography

Abstract

Transabdominal-US is the first-line imaging modality used to assess the whole liver parenchyma and vascularization; EUS assessment of the liver is incomplete and is not sufficient to rule out the presence of focal liver lesions. On the other hand, due the high diagnostic yield in detecting very small (< 1 cm) lesions, EUS is considered complementary to radiological imaging techniques for the investigation of liver parenchyma. Scarce data are available regarding the investigation of liver parenchyma using both EUS-elastography (EUS-E) and CH-EUS. The aim of this review is to evaluate the clinical role of image enhancement techniques, namely EUS-E and contrast harmonic-EUS (CH-EUS), for the evaluation liver diseases. Despite a potential interest for the application of EUS-E in the assessment of liver diseases, available evidence relegates this technique only to research areas, such as the differential diagnosis between benign and malignant focal liver lesions and the quantification of liver fibrosis in diffuse parenchymal diseases. With the future introduction of EUS shear-wave elastography, interesting data can be obtained for the assessment of liver fibrosis during real-time EUS evaluation. The usefulness of CH-EUS for the evaluation of liver disease is limited by the intrinsic EUS ability to explore only the left lobe and a small part of the right lobe. CH-EUS could be used to increase the diagnostic ability of EUS for the detection and characterization of small lesions and for guiding tissue sampling. Targeting EUS-guided treatments with either EUS-E or CH-EUS might represent potential future applications.

Do we need elastography for EUS?

“…Preliminary experience is available showing that EUS elastography combined with contrast-enhanced EUS may facilitate characterization of solid focal liver lesions. [ 53 ]…”

Development of a novel rat model of heterogeneous hepatic injury by injection with colchicine via the splenic vein

“…Third, although the ADC value from DWI enables noninvasive prediction of heterogeneous hepatic injury, it is limited by its relatively poor spatial resolution. Further studies are needed to explore other techniques such as gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MRI, T1 mapping, and T2 mapping for assessing regional liver function in this model[ 28 , 33 ].…”

A Comprehensive Narrative Review on the Evolving Role of Endoscopic Ultrasound in Focal Solid Liver Lesions Diagnosis and Management

“…A histogram cutoff value of 170 showed the best distinguishing ability of benign to malignant lesions with 92.5% sensitivity, 88.8% specificity, 88.6% accuracy, 86.7% positive predictive value, and 92.3% negative predictive value [20]. Moreover, the introduction of UCA either under Doppler by CE-EUS [21] or contrast harmonic-EUS (CH-EUS) has added significantly to the EUS-capability of detecting and characterizing focal liver lesions by improving the visibility of the microvascular architecture, thus allowing a differentiation between benign and malignant lesions [22][23][24] The unique property of UCA in focal liver lesions diagnosis takes advantage of the dual blood supply of the liver, which is divided into the arterial phase, lasting up to 30 s from injection during its enhancement and increasing progressively, the portal phase, lasting from 30-120 s, and the venous phase thereafter. Given that focal liver lesions have unique characteristics of vascular enhancement and washout, these techniques provide an excellent and promising tool to accurately define the lesion nature [25,26].…”