Korean J Radiol.  2019 Sep;20(9):1342-1357. 10.3348/kjr.2019.0002.

Quantitative Imaging in Pediatric Hepatobiliary Disease

• Yoon H
• Shin HJ
• Kim MJ
• Lee MJ

• KMID: 2455763
• DOI: http://doi.org/10.3348/kjr.2019.0002

Abstract

Pediatric hepatobiliary imaging is important for evaluation of not only congenital or structural disease but also metabolic or diffuse parenchymal disease and tumors. A variety of ultrasonography and magnetic resonance imaging (MRI) techniques can be used for these assessments. In ultrasonography, conventional ultrasound imaging as well as vascular imaging, elastography, and contrast-enhanced ultrasonography can be used, while in MRI, fat quantification, T2/T2* mapping, diffusion-weighted imaging, magnetic resonance elastography, and dynamic contrast-enhanced MRI can be performed. These techniques may be helpful for evaluation of biliary atresia, hepatic fibrosis, nonalcoholic fatty liver disease, sinusoidal obstruction syndrome, and hepatic masses in children. In this review, we discuss each tool in the context of management of hepatobiliary disease in children, and cover various imaging techniques in the context of the relevant physics and their clinical applications for patient care.

Keyword

Child; Liver; Ultrasonography; Elasticity imaging techniques; Magnetic resonance imaging

MeSH Terms

Biliary Atresia
Child
Elasticity Imaging Techniques
Fibrosis
Hepatic Veno-Occlusive Disease
Humans
Liver
Magnetic Resonance Imaging
Non-alcoholic Fatty Liver Disease
Patient Care
Ultrasonography

Figure

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  Fig. 1 Animal model of biliary obstruction for hepatic fibrosis evaluation. A. Liver ultrasonography after bile duct ligation in rabbit shows diffuse intrahepatic bile duct dilatation (arrows). B. Contrast-enhanced ultrasonography of liver shows perfusion curve of liver parenchymal enhancement. Peak signal intensity was 11.83 dB in this case and hepatic fibrosis grade was 2. LDRW WIWO = local density random walk wash in wash out, ROI = region of interest

• 

  Fig. 2 16-year-old male with hemolytic anemia and diffuse siderosis after splenectomy. A. Axial T2-weighted MR image shows diffusely decreased T2 signal intensity of liver parenchyma. In-phase (B) and opposed-phase (C) T1-weighted gradient-recalled echo images show no remarkable signal decrease on opposed-phase image. D. R2* parametric map demonstrates mild degree of iron overload in liver with R2* value of 329 s-1 at 3T MRI. MR = magnetic resonance

• 

  Fig. 3 2-month-old girl with biliary atresia. A. Liver MRI with mono-, bi-, and stretched exponential model DWI shows red circular ROI in liver parenchyma. B. Curves can be obtained according to models. From these models, ADC value was 1.2 × 10−3 mm2/s, D* value was 19.6 × 10−3 mm2/s, f value was 0.2, D was 0.9 × 10−3 mm2/s, distributed diffusion coefficient was 1.1 × 10−3 mm2/s, and α value was 0.5. ADC = apparent diffusion coefficient, D = true diffusion, D* = pseudo-diffusion, DWI = diffusion-weighted imaging, f = perfusion fraction, α = heterogeneity index

• 

  Fig. 4 12-year-old girl with liver fibrosis after Kasai operation for biliary atresia. A. Liver shows periportal hyperechogenicity (arrow) with left lobe atrophic change and lobulated contour. B. Shear wave elastography image of liver shows blue color in acquisition box with measured mean elasticity value of 8.0 kPa. Value in transient elastography was 7.7 kPa (not shown). C. Patient showed splenomegaly considering her age (more than 11.6 cm, not shown), and spleen shear wave elastography value was 23.9 kPa.

• 

  Fig. 5 9-year-old girl with biliary atresia after Kasai operation and grade 2 gastroesophageal varices. A. Axial T2-weighted imaging of liver shows hypertrophied right lobe and atrophic left lobe of liver with splenomegaly and engorged portal collateral vessels. B. Color map in MR elastography shows green to red color of liver, indicating increased stiffness. Measured mean liver elasticity was 4.1 kPa. C. Two years later, axial T2-weighted MR image shows aggravated liver cirrhosis with partial splenic artery embolization status in this patient. D. On follow-up MR elastography imaging, liver stiffness further increased, with mean value of 6.9 kPa. This patient underwent liver transplantation 2 months after last exam.

• 

  Fig. 6 9-year-old boy with biliary atresia and previous Kasai operation. A. Coronal single-shot fast spin-echo T2-weighted image shows multiple tiny intrahepatic biliary cysts (arrow) in liver and splenomegaly. Patient also showed engorged mesenteric veins (arrowhead) at right subhepatic area, suggesting portosystemic collateral pathways. B. MR elastography wave image shows thick blue and red waves within liver, consistent with elevated shear wave speed (increased wavelength), reflective of liver stiffness. C. MR elastogram color map shows blue to green color of liver and red color of spleen. Measured hepatic stiffness was 3.2 kPa and spleen stiffness was 10.7 kPa.

• 

  Fig. 7 10-year-old boy with fatty liver. A. Grayscale image obtained with liver ultrasonography demonstrates hepatomegaly with diffusely increased liver parenchymal echo, indistinct hepatic veins, and poor diaphragm visualization. B. Longitudinal scan of liver including right kidney shows echo difference and hepatorenal ratio of 2.3, which is above cutoff value of 1.5 in children. On liver MRI, hepatic fat fraction was 32%.

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  Fig. 8 11-year-old boy with hepatic steatosis. MR proton density fat fraction of liver was 31% when patient was 6 years old (A) and increased to 51%, 5 years later (B).

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  Fig. 9 13-year-old girl with sinusoidal obstruction syndrome or veno-occlusive disease. A. Transverse ultrasound image of liver shows hepatomegaly with periportal edema and collapsed gallbladder wall edema (arrow). There was moderate amount of ascites (not shown). B. Doppler image of liver hilum shows decreased portal vein flow. C. Shear wave elastography image of liver shows yellow to red color in acquisition box with measured mean elasticity value of 40.5 kPa.

• 

  Fig. 10 4-month-old girl with hepatic masses. A. Multiple high signal intensity masses are noted in liver on T2-weighted image. B. On DWI, masses show high signal intensity on high b-value. C. On ADC map, masses show low ADC value, indicating that they are malignant. Masses were confirmed as hepatoblastoma.

• 

  Fig. 11 3-month-old boy with liver hemangioma. A. DCE MRI of liver shows enhancing mass lesions in right lobe with central non-enhancing portion. B. When drawing ROI in mass lesion as in (A), slope showing early arterial and persistent enhancement was obtained. C. Values obtained from multi-parametric maps were as follows: Ktrans = 174.3 × 10−3/min, Kep = 490.9 × 10−3/min, Ve = 355.1 × 10−3, and Vp = 41.6 × 10−3. AIF = arterial input function, DCE = dynamic contrast-enhanced, Kep = rate constant (Ktrans/Ve), Ktrans = volume transfer constant between plasma and extravascular extracellular space, Ve = volume of extracellular compartment, Vp = volume of plasma compartment

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  Fig. 12 4-year-old girl with hepatoblastoma. A. At initial liver DCE MRI of hepatoblastoma, Ktrans was 86.7 × 10−3/min. B. Follow-up DCE MRI shows treatment response. At 3 months after chemotherapy, tumor size had decreased and Ktrans had also decreased to 70.6 × 10−3/min.

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