Contrast-enhanced ultrasound of benign and malignant liver lesions in children

Abstract

Contrast-enhanced ultrasound (CEUS) is increasingly being used in children. One of the most common referrals for CEUS performance is characterization of indeterminate focal liver lesions and follow-up of known liver lesions. In this setting, CEUS is performed with intravenous administration of ultrasound contrast agents (UCAs). When injected into a vein, UCA microbubbles remain confined within the vascular network until they dissipate. Therefore, visualization of UCA within the tissues and lesions corresponds to true blood flow. CEUS enables continuous, real-time observation of the enhancement pattern of a focal liver lesion, allowing in most cases for a definite diagnosis and obviating the need for further cross-sectional imaging or other interventional procedures. The recent approval of Lumason (Bracco Diagnostics, Monroe Township, NJ) for pediatric liver CEUS applications has spurred the widespread use of CEUS. In this review article we describe the role of CEUS in pediatric liver applications, focusing on the examination technique and interpretation of main imaging findings of the most commonly encountered benign and malignant focal liver lesions. We also compare the diagnostic performance of CEUS with other imaging modalities for accurate characterization of focal liver lesions.

Keywords: Benign; Children; Contrast-enhanced ultrasound; Lesion; Liver; Malignant; Ultrasound; Ultrasound contrast agents.

Fig. 1

Incidental liver hemangiomatosis in a 4-month-old boy. a Transverse gray-scale US shows multiple hypoechoic lesions throughout the liver. b–e Transverse contrast-enhanced ultrasound (CEUS) of the liver. Dual display of the gray-scale (left) and contrast-enhanced (right) image at 8 s (b) and contrast-only CEUS images at 10 s (c), 22 s (d) and 1 min 33 s (e) after contrast administration. Early peripheral enhancement is exemplified in the largest lesion (arrows), followed by centripetal enhancement and nearly complete and homogeneous enhancement of all lesions similar to the background hepatic parenchyma. No washout is noted in any of the lesions (e)

Fig. 2

Rapidly involuting congenital hemangioma in a 3-week-old boy with a congenital mass of the left liver lobe. a Transverse gray-scale US shows a large heterogeneous lesion (circle) within the left liver lobe. The volume of the lesion at initial scan was 41 mL. b–e Transverse contrast-enhanced ultrasound (CEUS) of the liver in contrast-only mode in the arterial phase at 11 s (b), 14 s (c) and 18 s (d), and in the portal venous phase 60 s after injection of the contrast agent (e). Rapid nodular enhancement progresses from the periphery (arrows) to the center, with incomplete enhancement in the central aspect (asterisks) of the lesion. In the follow-up US scans (not shown) except for residual calcifications there was near-complete regression of the lesion. Imaging features are typical for rapidly involuting congenital hemangioma. In this child, at 9 months of age the volume of the lesion had decreased at 2.6 mL, and at 5 years of age the lesion was barely visible with a measured residual volume of 0.4 mL

Fig. 3

Congenital hemangioma in a 2-week-old boy with elevated liver enzymes. a Transverse gray-scale US demonstrates a large focal liver lesion (arrows). b–d Transverse contrast-enhanced ultrasound (CEUS) images in contrast-only mode during dynamic enhancement phases. In the arterial phase (b), the lesion demonstrates peripheral, nodular, discontinuous enhancement pattern (arrows). In the portal venous phase (c), the lesion (arrow) appears homogeneously hyperenhancing. In the late phase (d), the lesion (arrow) remains hyperenhancing compared to the adjacent liver parenchyma. See Online Supplementary Material 1 for cinematic clip

Fig. 4

Focal nodular hyperplasia in a 17-year-old boy with abdominal pain. An incidentally detected focal liver lesion was found at gray-scale US (not shown here). a–d Transverse contrast-enhanced US images, in contrast-only mode during dynamic enhancement phases. In the early (a) and late (b) arterial phases, there is rapid spoke-wheel enhancement of the lesion (arrows) originating from the center (arrowhead). In the portal venous phase (c), the lesion (arrows) appears homogeneously hyperenhancing and remains hyperenhancing during the late phase (d), where a central hypoenhancing scar (arrowhead) is evident

Fig. 5

Hepatic adenoma and hepatocellular carcinoma in a 17-year-old girl with glycogen storage disease type 1 who was known to have multiple hepatic adenomas. a Transverse gray-scale US demonstrates two focal liver lesions. The larger lesion (solid arrow) appears with heterogeneous echotexture but is predominantly hypoechoic, and the smaller lesion (open arrow) is hyperechoic. Both lesions were further evaluated with contrast-enhanced ultrasound (CEUS). b–d Transverse CEUS images of the first lesion (arrows) in contrast-only mode demonstrate hyperenhancement in the arterial phase (b), iso- to slightly hyperenhancement in the portal venous phase (c) and isoenhancement to background liver in the late phase (d). Histological diagnosis: hepatic adenoma. e–g Transverse CEUS in contrast-only mode of the second lesion (arrows) demonstrates hyperenhancement in the arterial phase (e) and hypoenhancement in the portal venous (f) and late (g) phases. Histological diagnosis: hepatocellular carcinoma

Fig. 6

Focal fatty infiltration of the liver in a 16-year-old girl who presented with elevated liver enzymes. a Transverse gray-scale US demonstrates a focal hyperechoic lesion (arrow) within the subcapsular region of the liver. b Contrast-enhanced ultrasound (CEUS) of the liver in transverse plane with dual display of gray-scale (right) and contrast-enhanced (left) images. The lesion (arrows) on gray-scale US shows isoenhancement to the liver background on CEUS in the portal venous phase. It was isoenhanced in all other phases, too (not shown)

Fig. 7

Hepatoblastoma in an 11-day-old boy with a large congenital mass of the left liver lobe. a Gray-scale US shows a large mass with heterogeneous echotexture (circle) within the left liver lobe. b–f Contrast-enhanced ultrasound (CEUS) of the liver. Transverse CEUS in contrast-only mode in arterial phase at 10 s (b) and 14 s (c), in portal venous phase at 53 s (d) and in late-phase of enhancement >120 s after contrast injection (e, f). Rapid heterogeneous enhancement shows multiple irregular vessels (open arrowheads) centrally within the lesion in a disorganized pattern. One small region in the periphery of the lesion (solid arrowhead) shows persistent reduced enhancement, possibly corresponding to necrosis. Transverse CEUS during the late phase (e and later f) shows progressive washout (asterisks) centrally