Hepatoblastoma imaging with gadoxetate disodium-enhanced MRI--typical, atypical, pre- and post-treatment evaluation

Introduction to the COG Diagnostic Imaging Committee/SPR Oncology Committee White Papers: Rationale and methods

Pediatric cancer is a rare disease. Because of this, many sites do not have experience providing imaging for specific tumor types. The Children's Oncology Group Diagnostic Imaging Committee and the Society for Pediatric Radiology Oncology Committee are comprised of radiologists with expertise in pediatric cancer imaging. Recently, this group endeavored to create a series of 23 White Papers designed to provide evidence-based imaging recommendations and minimum achievable imaging protocols. The purpose of this manuscript is to describe the methods employed in authoring the White Paper series.

Imaging of pediatric liver tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Primary hepatic malignancies are relatively rare in the pediatric population, accounting for approximately 1%-2% of all pediatric tumors. Hepatoblastoma and hepatocellular carcinoma are the most common primary liver malignancies in children under the age of 5 years and over the age of 10 years, respectively. This paper provides consensus-based imaging recommendations for evaluation of patients with primary hepatic malignancies at diagnosis and follow-up during and after therapy.

Recent advances in surgical strategies and liver transplantation for hepatoblastoma

Hepatoblastoma (HB) is the most common malignant liver tumor in children. Although the development of treatment strategies with advances in chemotherapy has greatly improved the prognosis of HB, surgical resection and liver transplantation still play a vital role in the treatment of HB. In recent years, technological innovations have led to the development of new surgical approaches for HB. In this review, we describe the latest research on the surgical management of HB, including new imaging technologies, minimally invasive approaches, and the application of associating liver partition portal vein ligation for staged hepatectomy. We also discuss the current role of liver transplantation, use of ante-situm or ex-situ liver resection with auto-transplantation, and management of metastatic HB.

Role of Diffusion Weighted MRI (DW-MR) in Detection of Satellite Lesions Not Detected with Multiphase CT Scans in Hepatoblastoma and Its Implications for Management

OBJECTIVE

To evaluate the role of diffusion-weighted magnetic resonance imaging (DW-MR) in hepatoblastoma as compared to multiphase contrast enhanced computed tomography (CECT) scans for detection of satellite lesions.

METHODS

In this prospective study on new cases of hepatoblastoma, multiphase CECT scans and DW-MR were performed before initiation of chemotherapy. Results of interpretation were compared for detection of satellite lesions. PRETEXT grouping and risk categorization was done according to SIOPEL based on CECT scan.

RESULTS

Nine boys and 1 girl with hepatoblastoma, with median age of 11.5 mo were included. All patients were stratified as high-risk group with 2 (20%) in PRETEXT II and 8 (80%) in PRETEXT III. In 2 of 10 (20%) patients, additional satellite lesions were detected on DW-MR, which upgraded their stage. One of the two patients had one satellite lesion identified on CECT, while additional seven satellite lesions were identified on DW-MR imaging. For the other patient, CECT showed no satellite lesion while DW-MR detected six satellite lesions.

CONCLUSION

MRI has become the gold standard investigation for evaluation of hepatoblastoma. DW-MR, which is a contrast free technique, is a better tool for assessment of satellite lesions which are usually missed on CECT. This would help in proper staging, planning of management and prognostication.

Influence of age on gadoxetic acid disodium-induced transient respiratory motion artifacts in pediatric liver MRI

PURPOSE

Gd-EOB-DTPA-enhanced liver MRI is frequently compromised by transient severe motion artifacts (TSM) in the arterial phase, which limits image interpretation for the detection and differentiation of focal liver lesions and for the recognition of the arterial vasculature before and after liver transplantation. The purpose of this study was to investigate which patient factors affect TSM in children who undergo Gd-EOB-DTPA-enhanced liver MRI and whether younger children are affected as much as adolescents.

METHODS

One hundred and forty-eight patients (65 female, 83 male, 0.1-18.9 years old), who underwent 226 Gd-EOB-DTPA-enhanced MRIs were included retrospectively in this single-center study. The occurrence of TSM was assessed by three readers using a four-point Likert scale. The relation to age, gender, body mass index, indication for MRI, requirement for sedation, and MR repetition was investigated using uni- and multivariate logistic regression analysis.

RESULTS

In Gd-EOB-DTPA-enhanced MRIs, TSM occurred in 24 examinations (10.6%). Patients with TSM were significantly older than patients without TSM (median 14.3 years; range 10.1-18.1 vs. 12.4 years; range 0.1-18.9, p<0.001). TSM never appeared under sedation. Thirty of 50 scans in patients younger than 10 years were without sedation. TSM were not observed in non-sedated patients younger than 10 years of age (p = 0.028). In a logistic regression analysis, age remained the only cofactor independently associated with the occurrence of TSM (hazard ratio 9.152, p = 0.049).

CONCLUSION

TSM in Gd-EOB-DTPA-enhanced liver MRI do not appear in children under the age of 10 years.

Imaging for Staging of Pediatric Abdominal Tumors: An Update, From the AJR Special Series on Cancer Staging

The three most common pediatric solid tumors of the abdomen are neuroblastoma, Wilms tumor, and hepatoblastoma. These embryonal tumors most commonly present in the first decade of life. Each tumor has unique imaging findings, including locoregional presentation and patterns of distant spread. Neuroblastoma, Wilms tumor, and hepatoblastoma have unique staging systems that rely heavily on imaging and influence surgical and oncologic management. The staging systems include image-defined risk factors for neuroblastoma, the Children's Oncology Group staging system for Wilms tumor, and the pretreatment extent of tumor system (PRETEXT) for hepatoblastoma. It is important for radiologists to be aware of these staging systems to optimize image acquisition and interpretation. This article provides a practical and clinically oriented approach to the role of imaging in the staging of these common embryonal tumors of childhood. The selection among imaging modalities, key findings for determining tumor stage, and the role of imaging in posttreatment response evaluation and surveil-lance are discussed. Recent updates to the relevant staging systems are highlighted with attention to imaging findings of particular prognostic importance. The information presented will help radiologists tailor the imaging approach to the individual patient and guide optimal oncologic management.

Hepatic nodules with arterial phase hyperenhancement and washout on enhanced computed tomography/magnetic resonance imaging: how to avoid pitfalls

This essay aimed to illustrate the various hepatic nodules that may exhibit arterial phase hyperenhancement and washout on computed tomography/magnetic resonance imaging (CT/MRI). Hepatic nodules with arterial phase hyperenhancement and washout on CT/MRI include hepatocellular carcinoma, focal nodular hyperplasia-like nodules, serum amyloid A-positive hepatocellular neoplasms, intrahepatic cholangiocarcinoma, intrahepatic bile duct adenoma, hepatoblastoma, hepatocellular adenoma, hepatic epithelioid angiomyolipoma, and metastasis including neuroendocrine and gastrointestinal stromal tumors. Understanding the imaging findings is important to ensure correct diagnosis.

How Do Synchronous Lung Metastases Influence the Surgical Management of Children with Hepatoblastoma? An Update and Systematic Review of the Literature

Approximately 20% of children with hepatoblastoma (HB) have metastatic disease at diagnosis, most frequently in the lungs. In children with HB, lung metastatic disease is associated with poorer prognosis. Its treatment has been approached with a variety of methods that integrate chemotherapy and surgical resection. The timing and feasibility of complete extirpation of lung metastases, by chemotherapy and/or metastasectomy, is crucial for the surgical treatment of the primary liver tumor, which can vary from major hepatic resections to liver transplantation (LT). In children with unresectable HB, which can be surgically treated only by LT, the persistence of unresectable metastases after neoadjuvant chemotherapy excludes the possibility of recurring to LT with consequent negative impact on patients' outcomes. Due to limited evidence and experience, there is no consensus amongst oncologists and surgeons across institutions regarding the surgical treatment for HB with synchronous metastatic lung disease. This narrative review aimed to update the current management of pulmonary metastasis in children with HB and to define its role in the decision-making strategy for the surgical approach to primary liver tumours.

Use of Eovist in Pediatric Patients: Pearls and Pitfalls

Magnetic resonance imaging is excellent at characterizing pediatric hepatobiliary pathology. Noncontrast MRI is helpful due to T2 hyperintensity associated with bile, but contrast enhancement offers additional means of lesional characterization. In particular, hepatocyte-specific contrast agents such as gadoxetate disodium (Eovist) exhibit partial hepatobiliary excretion which may be leveraged in these contexts. In this review, we will discuss gadoxetate disodium usage, including a sample-imaging protocol, and demonstrate applications and limitations in the pediatric population.

Hepatoblastoma-The Evolution of Biology, Surgery, and Transplantation

The most common primary malignant liver tumor of childhood, hepatoblastoma has increased in incidence over the last 30 years, but little is still known about its pathogenesis. Discoveries in molecular biology provide clues but have yet to define targeted therapies. Disease-free survival varies according to stage, but is greater than 90% in favorable risk populations, in part due to improvements in chemotherapeutic regimens, surgical resection, and earlier referral to liver transplant centers. This article aims to highlight the principles of disease that guide current treatment algorithms. Surgical treatment, especially orthotopic liver transplantation, will also be emphasized in the context of the current Children's Oncology Group international study of pediatric liver cancer (AHEP-1531).

Staging and following common pediatric malignancies: MRI versus CT versus functional imaging

Most pediatric malignancies require some form of cross-sectional imaging, either for staging or response assessment. The majority of these are solid tumors and this review addresses the role of MRI, as well as other cross-sectional and functional imaging techniques, for evaluating the most common pediatric solid tumors. The primary emphasis is on neuroblastoma, hepatoblastoma and Wilms tumor, three of the most common non-central-nervous-system (CNS) pediatric solid tumors encountered in young children. The initial focus will be a review of the imaging techniques and approaches used for diagnosis, staging and early post-treatment response assessment, followed by a discussion of the role surveillance imaging plays in pediatric oncology and a brief review of other emerging imaging techniques. The lessons learned here can be applied to most other pediatric tumors, including rhabdomyosarcoma, Ewing sarcoma and osteosarcoma, as well as germ cell tumors, neurofibromatosis and other rare tumors. Although lymphoma, in particular Hodgkin lymphoma, represents one of the more common pediatric malignancies, this is not discussed in detail here. Rather, many of the lessons that we have learned from lymphoma, specifically with regard to how we integrate both anatomical imaging and functional imaging techniques, is applied to the discussion of the other pediatric solid tumors.

Pedunculated focal nodular hyperplasia in a healthy toddler

Focal nodular hyperplasia (FNH) is a benign hepatic tumor rarely seen in pediatric patients, with most cases reported in school-aged children with a history of malignancy, liver disease, chemotherapy, or hematopoietic stem cell therapy. Despite having advanced radiographic imaging, diagnosing FNH before surgical resection can be difficult. We report a rare case of pedunculated FNH presenting as a large abdominal mass palpated on physical exam in a healthy 3-year-old girl with no history of malignancy or underlying liver disease. Ultrasound, computed tomography, and magnetic resonance imaging (MRI) did not demonstrate the typical imaging characteristics of FNH, because the mass was pedunculated with a poorly visualized central scar. Because approximately 75% of all primary hepatic tumors in this age group are malignant, this report also discusses the importance of adding hepatobiliary phase imaging with MRI to avoid, if possible, the need for biopsy or surgical resection of a benign hepatic tumor.

2017 PRETEXT: radiologic staging system for primary hepatic malignancies of childhood revised for the Paediatric Hepatic International Tumour Trial (PHITT)

Imaging is crucial in the assessment of children with a primary hepatic malignancy. Since its inception in 1992, the PRETEXT (PRE-Treatment EXTent of tumor) system has become the primary method of risk stratification for hepatoblastoma and pediatric hepatocellular carcinoma in numerous cooperative group trials across the world. The PRETEXT system is made of two components: the PRETEXT group and the annotation factors. The PRETEXT group describes the extent of tumor within the liver while the annotation factors help to describe associated features such as vascular involvement (either portal vein or hepatic vein/inferior vena cava), extrahepatic disease, multifocality, tumor rupture and metastatic disease (to both the lungs and lymph nodes). This manuscript is written by members of the Children's Oncology Group (COG) in North America, the International Childhood Liver Tumors Strategy Group (SIOPEL) in Europe, and the Japanese Study Group for Pediatric Liver Tumor (JPLT; now part of the Japan Children's Cancer Group) and represents an international consensus update to the 2005 PRETEXT definitions. These definitions will be used in the forthcoming Trial to Pediatric Hepatic International Tumor Trial (PHITT).

Role of interventional radiology in managing pediatric liver tumors : Part 1: Endovascular interventions

Primary liver malignancies are rare in children. Hepatoblastoma and hepatocellular carcinoma (HCC) together represent the overwhelming majority of cases. Overall survival of hepatoblastoma approaches 80% with multimodal treatment approaches that include chemotherapy, surgery and transplantation. However, there remains a subset of children with hepatoblastoma in whom resection or transplantation is not possible. The 5-year survival for children diagnosed with HCC is less than 30% and remains a significant therapeutic challenge. The poor outcomes for children with primary liver tumors motivate investigation of new therapeutic alternatives. Interventional oncology offers a broad scope of percutaneous and transcatheter endovascular cancer therapies that might provide clinical benefits. Minimally invasive approaches are distinct from medical, surgical and radiation oncologic treatments, and in adults these approaches have been established as the fourth pillar of cancer care. Transarterial chemoembolization is a minimally invasive locoregional treatment option performed by interventional radiologists with level-I evidence as standard of care in adults with advanced liver malignancy; transarterial chemoembolization in adults has served to prolong disease-free progression, downstage and bridge patients for surgical and transplant interventions, and improve overall survival. However, while several groups have reported that transarterial chemoembolization is feasible in children, the published experience is limited primarily to small retrospective case series. The lack of prospective trial evidence has in part limited the utilization of transarterial chemoembolization in the pediatric patient population. The purpose of this article is to provide an overview of the role of interventional radiology in the diagnosis and endovascular management of hepatic malignancies in children.

Contrast-enhanced CT features of hepatoblastoma: Can we predict histopathology?

BACKGROUND

Hepatoblastoma is the most common hepatic malignancy occurring in the pediatric population. Intratumoral cellular behavior varies, and the small-cell undifferentiated histopathology carries a poorer prognosis than other tissue subtypes. Neoadjuvant chemotherapy is recommended for this tumor subtype prior to surgical resection in most cases. Early identification of tumors with poor prognosis could have a significant clinical impact. Objective The aim of this work was to identify imaging features of small-cell undifferentiated subtype hepatoblastoma that can help distinguish this subtype from more favorable tumors and potentially guide the clinical management. We also sought to characterize contrast-enhanced CT (CECT) features of hepatoblastoma that correlate with metastatic disease and patient outcome.

MATERIALS AND METHODS

Our study included 34 patients (24 males, 10 females) with a mean age of 16months (range: 0-46months) with surgically confirmed hepatoblastoma and available baseline abdominal imaging by CECT. Clinical data and CT abdominal images were retrospectively analyzed.

RESULTS

Five tumors with small-cell undifferentiated components were identified. All of these tumors demonstrated irregular margins on CT imaging. Advanced PRETEXT stage, vascular invasion and irregular margins were associated with metastatic disease and decreased survival. Capsular retraction was also significantly associated with decreased survival. Irregular tumor margins demonstrated statistically significant association with the presence of small-cell undifferentiated components. No other imaging feature showed statistically significant association.

CONCLUSION

Tumor margin irregularity, vascular invasion, capsular retraction, and PRETEXT stage correlate with worse patient outcomes. Irregular tumor margin was the only imaging feature significantly associated with more aggressive tumor subtype.

Practical use and pitfalls of hepatocyte-specific contrast agents (HSCAs) for pediatric hepatic and biliary magnetic resonance imaging

Magnetic resonance imaging is commonly used to evaluate for hepatic and biliary pathology in the pediatric population. Recently, there has been increased use of hepatocyte-specific contrast agents (HSCAs), such as Gadoxetate disodium in children. Traditionally, HSCAs have been used to characterize focal liver lesions. However, these agents can also be used to problem solve specific hepatic or biliary diagnostic dilemmas. The purpose of this manuscript is to review the practical uses of HSCA in children with both hepatic and biliary indications, and review the corresponding imaging findings. We will highlight the diagnostic uses of HSCA in children, as well as pitfalls encountered.

Malignant tumors of the liver in children

This article aims to give an overview of pediatric liver tumors; in particular of the two most frequently occurring groups of hepatoblastomas and hepatocellular carcinomas. Focus lays on achievements gained through worldwide collaboration. We present recent advances in insight, treatment results, and future questions to be asked. Increasing international collaboration between the four major Pediatric Liver Tumor Study Groups (SIOPEL/GPOH, COG, and JPLT) may serve as a paradigm to approach rare tumors. This international effort has been catalyzed by the Children's Hepatic tumor International Collaboration (CHIC) formation of a large collaborative database. Interrogation of this database has led to a new universal risk stratification system for hepatoblastoma using PRETEXT/POSTTEXT staging as a backbone. Pathologists in this international collaboration have established a new histopathological consensus classification for pediatric liver tumors. Concomitantly there have been advances in chemotherapy options, an increased role of liver transplantation for unresectable tumors, and a web portal system developed at www.siopel.org for international education, consultation, and collaboration. These achievements will be further tested and validated in the upcoming Paediatric Hepatic International Tumour Trial (PHITT).

Pediatric and adult trauma centers differ in evaluation, treatment, and outcomes for severely injured adolescents

BACKGROUND/PURPOSE

This study aims to investigate differences in imaging, procedure utilization, and clinical outcomes of severely injured adolescents treated at adult versus pediatric trauma centers.

METHODS

The National Trauma Data Bank was queried retrospectively for adolescents, 15-19years old, with a length of stay (LOS) >1day and Injury Severity Score (ISS) >25 treated at adult (ATC) or pediatric (PTC) Level 1 trauma centers from 2007 to 2011. Patient demographics and utilization of imaging and procedures were analyzed. Univariate and multivariate regression analysis was used to compare outcomes.

RESULTS

Of 12,861 adolescents, 51% were treated at ATC. Older age and more nonwhites were seen at ATC (p<0.01). Imaging and invasive procedures were more common at ATC (p<0.01). Shorter LOS (p=0.03) and higher home discharge rates (p<0.01) were seen at PTC. ISS and mortality did not differ. Age, race, ATC care (all p<0.01), and admission systolic blood pressure (SBP) (p=0.03) were predictors of CT utilization. ISS, SBP, and race (p<0.01) were risk factors for overall mortality; SBP (p=0.03) and ISS (p<0.01) predicted death from penetrating injury.

CONCLUSIONS

Severely injured adolescents experience improved outcomes and decreased imaging and invasive procedures without additional mortality risk when treated at PTC. PTC is an appropriate destination for severely injured adolescents.

Safety and Efficacy of Gadoxetate Disodium-Enhanced Liver MRI in Pediatric Patients Aged >2 Months to <18 Years-Results of a Retrospective, Multicenter Study

PURPOSE

To assess the safety and efficacy of gadoxetate disodium–enhanced liver MR imaging in pediatric patients.

MATERIAL AND METHODS

Retrospective, multicenter study including pediatric patients aged >2 months to <18 years who underwent contrast-enhanced liver MRI due to focal liver lesions. A single intravenous bolus injection of 0.025 to 0.05 mmol/kg body weight of gadoxetate disodium was administered. Adverse events (AEs) up to 24 hours after injection were recorded and a one-year follow-up was conducted for all serious and unexpected AEs. Efficacy was defined based on the additional diagnostic information obtained from the combined (pre- and postcontrast) image sets as compared with the precontrast image sets by blinded reading.

RESULTS

A total of 52 patients for safety and 51 patients for efficacy analyses were evaluated. Twenty-two patients (42.3%) reported a total of 51 serious AEs (SAEs) and one AE after one year. No SAE or AE was related to gadoxetate disodium injection. Gadoxetate disodium–related effects on vital signs were not seen. Additional diagnostic information was obtained for 86.3% of patients. The three most improved efficacy variables were lesion-to-background contrast, lesion characterization, and improved border delineation in 78.4%, 76.5%, and 70.6% of patients, respectively.

CONCLUSION

Gadoxetate disodium in pediatric patients did not raise any clinically significant safety concern. Contrast enhancement provided additional clinically relevant information.

Magnetic resonance imaging of primary pediatric liver tumors

Although primary hepatic neoplasms are less common than other intra-abdominal tumors in children, these neoplasms are a significant source of morbidity and mortality in the pediatric population. MRI is increasingly relied upon in the diagnostic evaluation of these lesions, both before and after treatment, and familiarity with the MRI findings associated with these neoplasms is a must for pediatric radiologists. Advances in MRI technology, particularly the advent of hepatocyte-specific gadolinium-based MRI contrast agents, have allowed for accurate characterization of several types of hepatic neoplasms on the basis of imaging appearance. In this review, we provide an overview of the approach to imaging hepatic neoplasms in children using MRI, including a sample imaging protocol. We also discuss the relevant clinical features and MRI findings of the most clinically relevant entities, including their appearance on post-contrast imaging using hepatocyte-specific gadolinium-based MRI contrast agents.

The impact of hepatocyte phase imaging from infancy to young adulthood in patients with a known or suspected liver lesion

OBJECTIVE

Hepatocyte-specific contrast agents are used to help characterize liver lesions. However, there are no studies evaluating the utility of these agents in detecting or diagnosing pediatric liver lesions. The purpose of this study is to assess the impact of the hepatocyte phase of imaging on lesion detection, tumor staging and diagnostic confidence.

MATERIALS AND METHODS

All patients undergoing an MRI between September 2010 and August 2012 using gadoxetate disodium as the contrast agent were included in this study. Each exam was duplicated so that one copy contained all sequences, including the hepatocyte phase of imaging, and the other copy contained all sequences except the hepatocyte phase of imaging. One reviewer evaluated all exams in a blinded, random fashion. Data tracked included imaging diagnosis, confidence in diagnosis, number of lesions and PRETEXT grade. The imaging diagnosis was compared to histopathology, when available. Data were analyzed for the study population as well as the subset of patients diagnosed with focal nodular hyperplasia (FNH).

RESULTS

There were 112 patients (56 male; mean age: 9.25 years) included in this study. A total of 33 patients had a malignant tumor and the remainder had either a benign lesion or no lesion. The addition of the hepatocyte phase of imaging significantly improved the diagnostic confidence for all patients (P < 0.0001) as well as specifically for patients diagnosed with FNH (P = 0.003). In nearly a quarter of patients, the hepatocyte phase of imaging allowed the reviewer to detect additional lesions (P = 0.005). In the patients with a malignant tumor, the addition of the hepatocyte phase of imaging changed the PRETEXT grade in 7/30 patients although the results were not significant (P = 0.161).

CONCLUSION

The addition of the hepatocyte phase of imaging helps to improve lesion detection and increase the diagnostic confidence for all liver tumors, as well as for FNH in particular.

Management of hepatoblastoma: an update

PURPOSE OF REVIEW

To summarize the current standards and guidelines for the diagnosis and management of hepatoblastoma, a rare pediatric liver tumor.

RECENT FINDINGS

Hepatoblastoma is the most common malignant liver tumor in childhood. International collaborative efforts have led to uniform implementation of the pretreatment extent of disease (PRETEXT) staging system as a means to establish consensus classification and assess upfront resectability. Additionally, current histopathological classification, in light of more advanced molecular profiling and immunohistochemical techniques and integration of tumor biomarkers into risk stratification, is reviewed. Multimodal therapy is composed of chemotherapy and surgical intervention. Achievement of complete surgical resection plays a key role in successful treatment for hepatoblastoma. Overall, outcomes have greatly improved over the past four decades because of advances in chemotherapeutic agents and administration protocols as well as innovations of surgical approach, including the use of vascular exclusion, ultrasonic dissection techniques, and liver transplantation. Challenges remain in management of high-risk patients as well as patients with recurrent or metastatic disease.

SUMMARY

Eventually, a more individualized approach to treating the different types of the heterogeneous spectrum of hepatoblastoma, in terms of different chemotherapeutic protocols and timing as well as type and extent of surgery, may become the basis of successful treatment in the more complex or advanced types of hepatoblastoma.

Multimodal therapy including liver transplantation for hepatic undifferentiated embryonal sarcoma

The outcomes of hepatic undifferentiated embryonal sarcoma (HUES) have historically been limited by persistent, unresectable disease and the subsequent development of disease resistance and dissemination. We present our institutional experience with HUES and assess current treatment trends and outcomes in the era of liver transplantation. We conducted a retrospective chart review of cases presenting with HUES at our institution over the past 10 years. The collected data included age, sex, presenting symptoms, imaging and the associated Pretreatment Extent of Disease (PRETEXT) score, pathology, chemotherapy, surgical interventions, and outcomes. Approval was obtained from the institutional review board of the Cincinnati Children's Hospital Medical Center. HUES was identified in 6 patients (4 males and 2 females) with a median age at diagnosis of 11 years (range = 7-13 years). Initial imaging was available for all but 1 patient. The PRETEXT stage for these patients ranged from II to III. One patient was diagnosed with lung metastases. Two patients underwent upfront resection, and 1 patient received neoadjuvant therapy and then conventional resection. Three patients were treated with orthotopic liver transplantation (OLT) after neoadjuvant chemotherapy (primary OLT in 2 cases and salvage OLT for local recurrence in 1 case). Two patients received posttransplant adjuvant chemotherapy. All 6 patients remained in clinical remission with a mean follow-up of 35 months (range = 12-84 months). In conclusion, OLT has rarely been reported as a treatment option for HUES. The addition of liver transplantation as a surgical option for treating patients with HUES can result in improved survival for patients whose tumors are initially unresectable or recur.

Hepatoblastoma state of the art: pre-treatment extent of disease, surgical resection guidelines and the role of liver transplantation

PURPOSE OF REVIEW

This is part two of a two-part state of the art--hepatoblastoma. International hepatoblastoma specialists were brought together to highlight advances, controversies, and future challenges in the treatment of this rare pediatric tumor.

RECENT FINDINGS

Pretreatment extent of disease (PRETEXT) is a grouping system introduced as part of the multicenter international childhood liver tumors strategy group, SIOPEL-1, study in 1990. The system has been refined over the ensuing years and has now come to be adopted for risk stratification by all of the major pediatric liver tumor multicenter trial groups. PRETEXT is being intensively studied in the current Children's Oncology Group (COG) AHEP-0731 trial in an attempt to validate interobserver reproducibility and ability to monitor response to neoadjuvant chemotherapy, and determine surgical resectability. PRETEXT is now used to identify those patients who are at risk for having an unresectable tumor and who should be referred to a liver specialty center with transplant capability early in their treatment schema.

SUMMARY

International collaborative efforts in hepatoblastoma have led to increased refinements in the use of the PRETEXT and post-treatment extent to define prognosis and surgical resectability. PRETEXT criteria which suggest a possible need for liver transplantation are discussed in detail.

Advances in pediatric oncology MRI

Refined stratification of disease is thought to result in better survival from childhood malignant disease while minimizing the adverse effects of anticancer therapies. There is a potential for magnetic resonance imaging (MRI) to contribute to such stratification by improved tissue characterization, anatomical depiction, staging, and assessment of early treatment response. Recent advances in pediatric MRI outside the central nervous system (CNS) are reviewed in this context. The focus is on new applications for conventional MRI and on clinical implementation of tissue-specific and quantitative techniques. This area is largely unexplored, and potential directions for research are indicated.

Imaging of multifocal liver lesions in children and adolescents

Multifocal liver lesions are encountered regularly in children and adolescents. By knowing the specific ultrasonographic, computed tomographic, and magnetic resonance imaging (MRI) features of benign and malignant pediatric liver lesions as well as the particular clinical setting, radiologists can frequently narrow the differential diagnosis and sometimes offer a definitive diagnosis. The purpose of this review article is to illustrate the imaging findings of numerous benign and malignant causes of multifocal liver lesions in the pediatric population.