Clinical application of liver MR imaging in Wilson's disease

Quantitative Liver Imaging in Children

ABSTRACT

In children and adults, quantitative imaging examinations determine the effectiveness of treatment for liver disease. However, pediatric liver disease differs in presentation from liver disease in adults. Children also needed to be followed for a longer period from onset and have less control of their bodies, showing more movement than adults during imaging examinations, which leads to a greater need for sedation. Thus, it is essential to appropriately tailor and accurately perform noninvasive imaging tests in these younger patients. This article is an overview of updated imaging techniques used to assess liver disease quantitatively in children. The common initial imaging study for diffuse liver disease in pediatric patients is ultrasound. In addition to preexisting echo analysis, newly developed attenuation imaging techniques have been introduced to evaluate fatty liver. Ultrasound elastography is also now actively used to evaluate liver conditions, and the broad age spectrum of the pediatric population requires caution to be taken even in the selection of probes. Magnetic resonance imaging (MRI) is another important imaging tool used to evaluate liver disease despite requiring sedation or anesthesia in young children because it allows quantitative analysis with sequences such as fat analysis and MR elastography. In addition to ultrasound and MRI, we review quantitative imaging methods specifically for fatty liver, Wilson disease, biliary atresia, hepatic fibrosis, Fontan-associated liver disease, autoimmune hepatitis, sinusoidal obstruction syndrome, and the transplanted liver. Lastly, concerns such as growth and motion that need to be addressed specifically for children are summarized.

Acute Liver Failure

Acute liver failure (ALF) is a rare but life-threatening disease process that can result in rapidly progressive encephalopathy, elevated intracranial pressure, and multiorgan failure. In the United States, the 2 most common causes of ALF in the intensive care unit (ICU) are acetaminophen overdose and hypoxic-ischemic hepatopathy. Less common causes of ALF include alcoholic hepatitis, nonacetaminophen drug-induced liver injury, acute viral hepatitis, Wilson's disease, autoimmune hepatitis, and acute fatty liver of pregnancy. Unfortunately, there are many cases in which the cause of liver failure is indeterminate. ALF is an ICU emergency that requires close monitoring, extensive workup to determine etiology, frequent support of hemodynamic, respiratory, and renal function, administration of targeted therapies depending on the cause, utilization of N-acetylcysteine if appropriate, and consideration for liver transplant in select cases. The primary objective of this article is to define, diagnose, and detail the management of ALF in an ICU setting.

Hepatic manifestations of systemic disease: an imaging-based review

The liver is responsible for many processes that maintain human metabolic homeostasis and can be affected by several pediatric systemic diseases. In this manuscript, we explore key pathological findings and imaging features across multiple modalities of a spectrum of congenital, metabolic and autoimmune disorders. Strengthening the radiologists' knowledge regarding potential hepatic manifestations of these systemic diseases will ultimately lead to improved care for pediatric patients.

Quantitative MR in Paediatric Patients with Wilson Disease: A Case Series Review

Wilson disease (WD) is a liver disorder characterized by improper copper metabolism. Although non-invasive tools are currently used to support diagnosis and management, this is still an area of unmet need, as patients present with a wide range of symptoms. Our aim was to investigate the potential utility of multiparametric magnetic resonance imaging (mpMRI) and quantitative magnetic resonance cholangiopancreatography (MRCP+) to support patient management. MRI examinations of 7 children and young adults aged 8–16 years (six at diagnosis) were performed alongside a standard of care clinical and histological examination. Images were quantitatively analyzed to derive metrics of liver (corrected T1 (cT1; fibro-inflammation), MR liver fat (proton density fat fraction; PDFF)), and biliary health (MRCP+). MRI–PDFF provided a more dynamic characterization of fat compared with that provided by ultrasound. Those with elevated histological scores of fibrosis, inflammation, and steatosis had elevated mpMRI values. MRCP+ managed to identify dilatations in the biliary tree which were not observed during the standard of care examination. mpMRI and MRCP+ metrics show early promise as markers to assess both liver and biliary health in Wilson disease. Investigations to understand and explore the utility of these markers are warranted and should be performed.

Other types of diffuse liver disease: is there a way to do it?

There are a variety of less common diffuse liver diseases that can be asymptomatic or cause severe liver dysfunction. For the majority of them, the association of clinical, laboratory, and imaging findings are needed to narrow the differential diagnosis. In this article, we will review and describe the rarer diffuse liver diseases including drug-related liver disease, inflammatory and infectious diseases, and deposition disorders such as amyloidosis, glycogen storage disease, Wilson's disease, and alpha-1 antitrypsin deficiency. Abdominal radiologists should be familiar with the imaging features of different types of diffuse liver diseases to help the multidisciplinary team involved in the treatment of these patients. The data related to some of these conditions are scarce and sometimes experimental, but we want to demonstrate to the reader the value of imaging techniques in their analysis and introduce the potential of new imaging methods.

Benign and malignant mimickers of infiltrative hepatocellular carcinoma: tips and tricks for differential diagnosis on CT and MRI

Hepatocellular carcinoma (HCC) may have an infiltrative appearance in about 8-20% of cases. Infiltrative HCC can be a challenging diagnosis and it is associated with the worst overall survival among HCC patients. Infiltrative HCC is characterized by the spread of multiple minute nodules throughout the liver, without a dominant one, ultimately resulting into macrovascular invasion. On CT and MRI, infiltrative HCC appears as an ill-defined, large mass, with variable degree of enhancement, and satellite neoplastic nodules in up to 52% of patients. On MRI, it may show restriction on diffusion weighted imaging, hyperintensity on T2- and hypointensity on T1-weighted images, and, if hepatobiliary agent is used, hypointensity on hepatobiliary phase. Infiltrative HCC must be differentiated from other liver diseases, such as focal confluent fibrosis, steatosis, amyloidosis, vascular disorders of the liver, cholangiocarcinoma, and diffuse metastatic disease. In cirrhotic patients, the identification of vascular tumor invasion of the portal vein and its differentiation from bland thrombosis is of utmost importance for patient management. On contrast enhanced CT and MRI, portal vein tumor thrombosis appears as an enhancing thrombus within the portal vein, close to the main tumor and results into vein enlargement. The aim of this pictorial review is to show CT and MRI features that allow the diagnosis of infiltrative HCC and portal vein tumor thrombosis. A particular point of interest includes the tips and tricks for differential diagnosis with potential mimickers of infiltrative HCC.

Assessment of the Hallmarks of Wilson Disease in CT Scan Imaging

INTRODUCTION

Owing to nonspecific clinical symptoms, Wilson disease (WD) diagnosis is often missed or delayed; hence, many patients reach end-stage liver disease. When cirrhosis takes place, it is difficult to distinguish between WD and other causes of cirrhosis by imaging alone. This study outlines abdominal computed tomography (CT) imaging findings that occur more frequently in patients with WD cirrhosis.

MATERIAL AND METHODS

Fifty-seven patients with WD who had referred for liver transplantation took part in this study and underwent dynamic liver CT examination before transplantation. Qualitative and quantitative parameters including liver density, contour irregularity, dysmorphia, hypertrophy of caudate lobe, presence of focal parenchymal lesion, thickness of perihepatic fat layer, periportal thickness, lymphadenopathy, and other associated findings were recorded and evaluated.

RESULTS

Among these patients, 85.9% had contour irregularity, 28% had hepatic dysmorphia, and periportal thickening and cholelithiasis were found in 25.5% and 12.3% of patients, respectively. Splenomegaly, lymphadenopathy, and portosystemic shunting were observed in all patients. Also, hyperdense nodules (>20 mm) and honeycomb pattern were detected in 65.2% and 15.2% of patients, respectively, in the arterial phase. In the portal phase, these findings were detected only in 13% and 4.3% of patients. Hypertrophy of caudate lobe was seen only in 12.2% of patients.

CONCLUSION

WD-associated cirrhosis has many CT imaging findings, although most of them are nonspecific. Some findings, such as hyperdense nodules and honeycomb pattern in non-contrast-enhanced CT scan and arterial phase of triphasic CT scan with lack of hypertrophy of caudate lobes, are hallmarks of WD.

Wilson's disease: A 2017 update

Wilson's disease (WD) is characterised by a deleterious accumulation of copper in the liver and brain. It is one of those rare genetic disorders that benefits from effective and lifelong treatments that have dramatically transformed the prognosis of the disease. In Europe, its clinical prevalence is estimated at between 1.2 and 2/100,000 but the genetic prevalence is higher, at around 1/7000. Incomplete penetrance of the gene or the presence of modifier genes may account for the difference between the calculated genetic prevalence and the number of patients diagnosed with WD. The clinical spectrum of WD is broader as expected with mild clinical presentations and late onset of the disease after the age of 40 in 6% of patients. WD is usually suspected when ceruloplasmin and serum copper levels are low and 24h urinary copper excretion is elevated. Recently, a major diagnostic advance was achieved with implementation of the direct assay of "free copper", or exchangeable copper (CuEXC). The relative exchangeable copper (REC) that corresponds to the ratio between CuEXC and total serum copper enables a diagnosis of WD with high sensitivity and specificity when REC>18.5%. Moreover, CuEXC values at diagnosis are a marker of extrahepatic involvement and its severity. A value of >2.08μmol/L is suggestive of corneal and brain involvement (Se=86%, Sp=94%), and the disease will be more clinically and radiologically severe as values rise. The use of FibroScan^® is becoming more widespread to assess liver stiffness measurements in WD patients. 6.6kPa is considered to be a threshold value between mild and moderate fibrosis, whereas a value higher than 8.4 is indicative of severe fibrosis. More studies are now necessary to confirm the usefulness of Fibroscan^® in managing chronic therapy for WD patients. Treatment of this disease is based on an initial active and prolonged chelating phase (with D-Penicillamine or Trientine) followed by maintenance with Trientine or zinc salt. The two major problems that may be encountered are neurological worsening during the initial phase and non-compliance with treatment during maintenance therapy. Liver transplantation is the recommended therapeutic option in WD with acute liver failure or end-stage liver cirrhosis; its indication should be considered when neurological status deteriorates rapidly despite effective chelation. Regular clinical, biological and liver ultrasound follow-up is essential to evaluate efficacy, tolerance and treatment compliance, but also to detect the onset of hepatocellular carcinoma on a cirrhotic liver. There are hopes in the near future with the introduction of a new chelator and inhibitor of copper absorption, tetrathiomolybdate (TTM) and the development of gene therapy.

Hepatic features of Wilson disease

In Wilson disease (WD) defective AT7B function leads to biliary copper excretion and pathologic copper accumulation, particularly in liver and brain, where it induces cellular damage. Liver disease most often precedes neurologic or psychiatric manifestations. In most patients with neurologic or psychiatric symptoms there is some degree of liver disease at the time of disease presentation. Hepatic manifestations of WD can be extremely variable. Patients with clinically asymptomatic WD are often found by family screening or identified on routine laboratory testing. Others may have a clinical picture of chronic active hepatitis or of end-stage liver disease with cirrhosis. A minority present with acute liver failure, often on the background of advanced fibrosis. Complications from liver disease may be related to portal hypertension and concomitant liver disease may accelerate the course of liver disease. Liver cancer may occur in patients with WD, most commonly when cirrhosis and inflammation are present. The prognosis of patients with WD is excellent, especially for those without cirrhosis at the time of diagnosis, but requires timely initiation of appropriate therapy specific for WD and for the patient's liver disease independent of WD.

MR imaging features of focal liver lesions in Wilson disease

Hepatic involvement in Wilson disease (WD) manifests as a diffuse chronic disease in the majority of patients. However, in a subset of patients focal liver lesions may develop, presenting with a wide range of imaging features. The majority of focal liver lesions in patients with WD are benign nodules, but there are reports that have described malignant liver tumors or dysplastic nodules in these patients. Because of the possibility of malignant transformation of liver nodules, major concerns have been raised with respect to the management and follow-up of patients with WD in whom focal liver lesions have been identified. The assessment of liver involvement in patients with WD is generally performed with ultrasonography. However, ultrasonography conveys limited specificity so that magnetic resonance (MR) imaging is often performed to improve lesion characterization. This review was performed to illustrate the spectrum of MR imaging features of focal liver lesions that develop in patients with WD. It is assumed that familiarity with the MR imaging presentation of focal liver lesions in WD may help clarify the actual nature of hepatic nodules in patients with this condition.

Diagnosis of Wilson disease in young children: molecular genetic testing and a paradigm shift from the laboratory diagnosis

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism that results in accumulation of copper primarily in the liver, brain and cornea. Mutations in the WD gene, ATP7B, cause failure of copper excretion from hepatocyte into bile and a defective synthesis of ceruloplasmin. More than 500 mutations are now recognized, scattered throughout the ATP7B gene. Since WD has protean clinical presentations, awareness of WD in clinical practice is important for the early diagnosis and prevention of accumulated copper toxicity. Molecular genetic testing is playing an increasingly important role in the diagnosis of WD in uncertain cases and family screening. Siblings should be screened for WD once an index case has been diagnosed. Discrimination of heterozygotes from asymptomatic patients is essential to avoid inappropriate lifelong therapy for heterozygotes. Genetic testing, either by haplotype analysis or by mutation analysis, is the only definite solution for differentiating heterozygote carriers from affected asymptomatic patients. Routine genetic testing, because of the multitude of documented mutations, has been thought to be impractical until recently. However, genetic testing is now being more actively applied to the diagnosis of WD, particularly in young children in whom conventional biochemical diagnosis has much limitation and only genetic testing is able to confirm WD. Because advancement of modern biochemical technology now allows more rapid, easier, and less expensive mutation detection, direct DNA sequencing could be actively considered as the primary mode of diagnostic investigation rather than a supplementary test to the conventional biochemical tests. This review will focus on the recent advancement of molecular genetics and genetic diagnosis of WD in very young children on the basis of research data of the Seoul National University Children's Hospital and recent literature.

Experimental evaluation of accelerated T1rho relaxation quantification in human liver using limited spin-lock times

Objective

It was reported lately that to obtain consistent liver T1rho measurement, at 3T MRI using six spin-lock times (SLTs), is feasible. In this study, the feasibility of using three or two SLT points to measure liver T1rho relaxation time was explored.

Materials and Methods

Seventeen healthy volunteers underwent 36 examinations. Three representative axial slices were selected to cut through the upper, middle, and lower liver. A rotary echo spin-lock pulse was implemented in a 2D fast field echo sequence. Spin-lock frequency was 500 Hz and the spin-lock times of 1, 10, 20, 30, 40, and 50 milliseconds (ms) were used for T1rho mapping. T1rho maps were constructed by using all 6 SLT points, three SLT points of 1, 20, and 50 ms, or two SLTs of 1 and 50 ms, respectively. Intra-class correlation coefficient (ICC) and Bland and Altman plot were used to assess the measurement agreement.

Results

Two examinations were excluded, due to motion artifact at the SLT of 50 ms. With the remaining 34 examinations, the ICC for 6-SLT vs. 3-SLT T1rho measurements was 0.922, while the ICC for 6-SLT vs. 2-SLT T1rho measurement was 0.756. The Bland and Altman analysis showed a mean difference of 0.19 (95% limits of agreement: -1.34, 1.73) for 6-SLT vs. 3-SLT T1rho measurement, and the mean difference of 0.89 (95% limits of agreement: -1.67, 3.45) for 6-SLT vs. 2-SLT T1rho measurement. The scan re-scan reproducibility ICC (n = 11 subjects) was 0.755, 0.727, and 0.528 for 6-SLT measurement, 3-SLT measurement, and 2-SLT measurement, respectively.

Conclusion

Adopting 3 SLTs of 1, 20, and 50 ms can be an acceptable alternative for the liver T1rho measurement, while 2 SLTs of 1 and 50 ms do not provide reliable measurement.

Are irreversible morphological [corrected] signs of portal hypertension in neurological form of Wilson's disease associated with treatment delay? A pilot study

Aim of this study was to evaluate the rate of morphological liver and spleen abnormalities in patients with neurological clinical presentation of Wilson's disease (WD). Fourteen patients with neurological presentation of WD divided into group A (5 patients who initiated chelating therapy <24 months from the first symptoms) and group B (9 patients whose therapy started ≥24 months after the initial symptoms) underwent abdominal MRI examination. Abnormal findings on abdominal MRI were present in 28% of patients with neurological form of WD. Significant hepatosplenomegaly was present in none of the patients from group A and in 4 (44%) patients from group B. In addition, macronodular liver cirrhosis and peritoneal effusion were evident in two and one patient from group B, respectively, and in none of the patients from group A. Our results suggest that severe portal hypertension and liver damage in patients with neurological presentation of WD might be reversible or do not even develop if chelating treatment is initiated <2 years after the onset of symptoms.

[Diffuse and vascular hepatic diseases]

In addition to focal liver lesions, diffuse and vascular disorders of the liver represent a wide spectrum of liver diseases which are from the radiological point of view often difficult or nearly impossible to diagnose. Classical diagnostic methods are computed tomography and magnetic resonance imaging in addition to ultrasound. Diffuse parenchymal damage caused by diseases of various etiologies is therefore difficult to evaluate because it often lacks characteristic morphological features. For hepatic steatosis, hemochromatosis/siderosis as an example of a diffuse storage disease and sarcoidosis and candidiasis as infectious/inflammatory diseases, an image-based diagnosis is appropriate in some cases. For most diffuse liver diseases, however only nonspecific changes are visualized. Vascular pathologies of the liver, such as the Budd-Chiari syndrome and portal vein thrombosis, however, can usually be diagnosed very clearly using radiology and there is also a very effective interventional radiological treatment. Chronic diseases very often culminate in liver cirrhosis which is highly associated with an increased risk of liver cancer.