The real capabilities of contrast-enhanced ultrasound in the characterization of solid focal liver lesions

Abstract

Contrast-enhanced US (CEUS) using intravenous agents is a rapidly evolving field even though the main clinically recognized application is the characterization of focal liver lesions. Several reports have described the improvement provided by CEUS in the characterization of focal liver lesions in comparison to unenhanced US. CEUS with low transmit power insonation allows the real-time assessment of focal liver lesion contrast enhancement and vascularity during the different dynamic phases after injection of an intravenous contrast agent. CEUS allows the accurate characterization of focal liver lesions as benign or malignant based on the lesion contrast enhancement pattern during the arterial phase and lesion vascularity during portal-late phase in comparison to the adjacent liver parenchyma. During the portal-late phase, benign lesions present prevalently a sustained contrast enhancement with hyper or isovascular appearance to the adjacent liver while malignant lesions present prevalently microbubble washout with hypovascular appearance. On the other hand, the histology of focal liver lesions can only be confidently predicted in selected cases by CEUS, as in liver haemangiomas presenting typical nodular peripheral enhancement with subsequent centripetal fill-in and focal nodular hyperplasia with central spoke wheelshaped contrast enhancement.Grey-scale ultrasound (US) is the most widespread imaging procedure for investigating the liver parenchyma due to its relative low cost, availability, safety, and high patient acceptance. However conventional unenhanced gray-scale US is somewhat limited in characterizing focal liver lesions, and several papers have described the general capabilities of contrast-enhanced US (CEUS) in improving focal liver lesion characterization [1][2][3][4][5][6][7][8][9][10][11].Recently, European Radiology has published several papers regarding the capabilities of CEUS in focal liver lesion characterization [12][13][14][15][16]. Soussan et al. [16] presented an interesting study evaluating the role of CEUS in the characterization of solid focal liver lesions in comparison to contrast-enhanced MR imaging. In this study authors analysed a series of 47 patients with 50 incidental focal liver lesions-24 focal nodular hyperplasias (FNHs), 11 hepatocellar adenomas, 10 haemangiomas, 1 focal fatty changes, and 4 malignancies including 2 hepatocellular adenomas with malignant foci, 1 hepatocellular carcinoma (HCC), and 1 epithelioid haemangioendotheliomadetected by US and scheduled for contrast-enhanced MR imaging. All patients underwent CEUS after intravenous injection of an US contrast agent consisting of sulphur hexafluoride-filled microbubbles (SonoVue, Bracco, Italy). The MR images and CEUS cine-clips of each lesion were randomly assigned to two blinded readers, with 17 and 22 years of experience in MR imaging and 8 years of experience in CEUS, who independently reviewed all the examinations and were asked to provide the most likely histological diagnosis for each focal liver lesion a...

Focal nodular hyperplasia of the liver: an emerging complication of hematopoietic SCT in children

“…34,36 Color Doppler US and CEUS can be used to increase US diagnostic accuracy. 37 MRI has been shown to be the most accurate imaging modality (sensitivity 81.3%). 33 Both US and MRI avoid exposure to radiation, and this is a significant advantage in such a cohort of patients at risk of secondary malignancies.…”

Analysis of only 0-1 min clip or 1-4 min Clip for focal liver lesions during contrast-enhanced ultrasonography

“…Malignancies typically show low echo-signal intensity at late phase [5,6], and the contrast pattern that characterizes benign FLLs is the absence of wash-out in the portal-venous and late phases [2]. Besides, benign and malignant FLLs may occur in cirrhosis and fatty liver [7,8].…”

“…Unfortunately, until now, there has been no systematic report on the CEUS appearance of IP, which needs further study. In routine clinical practice, a definitive and exact differential diagnosis of FLLs with CEUS entire clip is possible only in some types of lesions, whilst the simple categorization of a lesion as benign or malignant can be achieved with extremely high sensitivity (>90 %) and specificity [2], as well as with an accuracy comparable to CT or MRI in most series [23][24][25][26]. Additionally, in typical lesions the 0-1min clip and 1-4min clip could be comparable to the entire clip in diagnosis of FLLs aforementioned.…”

“…The injection of ultrasound contrast agents (USCA) and the use of specialized imaging techniques now allow to display tissue macro and micro-vascularization similarly to what is seen with contrast-enhanced computed tomography (CECT) or magnetic resonance imaging (CEMRI) [1]. Ultrasound contrast agents present a pure intravascular distribution and do not leak in the interstitial space but persist in the sinusoids and portal vessels without the evidence of any equilibrium phase [2]. The peculiar hepatic vascularization allows defining different vascular phases.…”

“…Several papers have described the general capabilities of CEUS in improving focal liver lesion characterization [2]. CEUS is now a reliable imaging tool with wellestablished applications in the characterization of liver lesions with the possibility of prolonged liver ultrasound examination, and is easily performed.…”