Incidence and etiology of new liver lesions in pediatric patients previously treated for malignancy

Contrast enhanced ultrasound of liver lesions in patients treated for childhood malignancies

BACKGROUND

Patients treated for cancer have a higher incidence of focal liver lesions than the general population and there is often concern for a malignant etiology. This can result in patient, caregiver and physician anxiety and is managed by a "wait and watch" approach, or immediate additional imaging, or biopsy, depending on the degree of clinical concern. Because it is a low-cost, easily accessible, radiation and sedation free modality, we investigated the value of contrast enhanced ultrasound (CEUS) to accurately distinguish benign from malignant liver lesions in patients treated for childhood malignancies.

METHODS

We performed an IRB approved retrospective study of 68 subjects who were newly diagnosed, on treatment or off treatment for a pediatric malignancy and had liver lesions discovered on CT, MRI or non-contrast ultrasound and subsequently underwent CEUS between September 2013 and September 2021. Two experienced pediatric radiologists and a radiology trainee, blinded to the etiology of the liver lesions, independently reviewed the CEUS examinations and categorized lesions as benign, indeterminate, or malignant. The reference standard was biopsy for 19 lesions and clinical follow-up for 49. The sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy of CEUS were calculated using only the benign and malignant CEUS classifications. Inter-reviewer agreement was assessed by Cohen's kappa statistic.

RESULTS

There were 26 males and 42 females, mean age, 14.9 years (range, 1-52 years). Fifty subjects were off therapy, twelve receiving treatment, and six with newly diagnosed cancer. By the reference standard, 59 (87%) lesions were benign and 9 (13%) were malignant. Sensitivities of CEUS for the three reviewers ranged from 83 to 100% (95% CI, 35.9-100%), specificities from 93.1 to 96.0% (95% CI, 83.5-99.6%), PPV 60.0-71.4% (95% CI, 29.0-96.3%), NPV 98.0-100% (95% CI, 89.2-100%) and accuracy from 93.8 to 94.6% (95% CI, 85.1-99.7%). The kappa statistic for agreement between the two experienced radiologists was moderate at 0.58.

CONCLUSIONS

CEUS is highly accurate in distinguishing benign from malignant etiologies of liver lesions in patients treated for pediatric malignancies.

Hepatic focal nodular hyperplasia during follow-up of patients after cyclophosphamide- or oxaliplatin-based chemotherapy: differentiation from liver metastasis

OBJECTIVES

Newly detected hepatic nodules during follow-up of cancer survivors receiving chemotherapy may pose a diagnostic dilemma. We investigated a series of hepatic focal nodular hyperplasia (FNH) diagnosed by either typical MRI features and follow-up or pathology in cancer survivors.

METHODS

This retrospective study evaluated 38 patients with tumours who developed new hepatic FNH after cyclophosphamide-based (n = 19) and oxaliplatin-based (n = 19) chemotherapies. The main tumour types were breast cancer (n = 18) and colorectal cancer (n = 17). MRI findings, clinical features, and temporal evolution of all target hepatic lesions (n = 63) were reported. In addition, the two chemotherapy drug groups were compared.

RESULTS

The median interval between chemotherapy completion and FNH detection was 30.4 months (12.9, 49.4). Six patients underwent biopsy or surgery, while the remaining patients were diagnosed based on typical MRI features and long-term follow-up. Among the patients, 60.5% (23/38) presented with multiple nodules and 63 target lesions were detected. The median size of target lesions was 11.5 mm (8.4, 15.1). The median follow-up time was 32.5 months (21.2, 48.6), and 15 patients experienced changes in their lesions during the follow-up period (11 increased and 4 decreased). The cyclophosphamide-based treatment group had a younger population, a greater proportion of females, and a shorter time to discovery than the oxaliplatin-based chemotherapy group (all p ≤ 0.016).

CONCLUSIONS

FNH may occur in cancer survivors after cyclophosphamide- or oxaliplatin-based chemotherapy. Considering a patient's treatment history and typical MRI findings can help avoid misdiagnosis and unnecessary invasive treatment.

CLINICAL RELEVANCE STATEMENT

When cancer survivors develop new hepatic nodules during follow-up, clinicians should think of the possibility of focal nodular hyperplasia in addition to liver metastasis, especially if the cancer survivors were previously treated with cyclophosphamide or oxaliplatin.

KEY POINTS

Cancer survivors, after chemotherapy, can develop hepatic focal nodular hyperplasia. Cyclophosphamide and oxaliplatin are two chemotherapeutic agents that predispose to focal nodular hyperplasia development. Focal nodular hyperplasia occurs at shorter intervals in patients treated with cyclophosphamide.

Superb Microvascular Imaging in Pediatric Focal Nodular Hyperplasia

OBJECTIVE

To investigate superb microvascular imaging (SMI), a novel Doppler ultrasound technique that can visualize low-velocity microvascular flow, for assessing pediatric focal nodular hyperplasia (FNH).

PATIENTS AND METHODS

Nine FNH lesions in 6 patients were enrolled. On SMI and color Doppler imaging (CDI), intralesional vascularity was assessed visually and categorized as typical spoke-wheel pattern (central vessel radiating from the center to the periphery), multifocal spoke-wheel pattern, and nonspecific pattern. We compared the vascular features of the lesions between SMI and CDI and evaluated vascular patterns according to lesion size.

RESULTS

In terms of vascularity pattern, the typical spoke-wheel pattern of FNH was noted more frequently on SMI (67%) than on CDI (11%; P < 0.05). In addition, a multifocal spoke-wheel pattern was noted in all remaining lesions (33%) on SMI. On the contrary, a nonspecific vascular pattern was detected in the majority (78%) of CDI. Regarding the lesion size and vascularity on SMI, the typical spoke-wheel pattern was seen more frequently in the small FNH group than in the large FNH group. The intralesional vascular signal was detected more frequently on SMI (100%) than on CDI (89%).

CONCLUSION

SMI is feasible in evaluating FNH in children and has a greater ability to demonstrate the spoke-wheel pattern than CDI.

Cancer Therapy-related Hepatic Injury in Children: Imaging Review from the Pediatric LI-RADS Working Group

The liver is the primary organ for the metabolism of many chemotherapeutic agents. Treatment-induced liver injury is common in children undergoing cancer therapy. Hepatic injury occurs due to various mechanisms, including biochemical cytotoxicity, hepatic vascular injury, radiation-induced cytotoxicity, and direct hepatic injury through minimally invasive and invasive surgical treatments. Treatment-induced liver injury can be seen contemporaneous with therapy and months to years after therapy is complete. Patients can develop a combination of hepatic injuries manifesting during and after treatment. Acute toxic effects of cancer therapy in children include hepatitis, steatosis, steatohepatitis, cholestasis, hemosiderosis, and vascular injury. Longer-term effects of cancer therapy include hepatic fibrosis, chronic liver failure, and development of focal liver lesions. Quantitative imaging techniques can provide useful metrics for disease diagnosis and monitoring, especially in treatment-related diffuse liver injury such as hepatic steatosis and steatohepatitis, hepatic iron deposition, and hepatic fibrosis. Focal liver lesions, including those developing as a result of treatment-related vascular injury such as focal nodular hyperplasia-like lesions and hepatic perfusion anomalies, as well as hepatic infections occurring as a consequence of immune suppression, can be anxiety provoking and confused with recurrent malignancy or hepatic metastases, although there often are imaging features that help elucidate the correct diagnosis. Radiologic evaluation, in conjunction with clinical and biochemical screening, is integral to diagnosing and monitoring hepatic complications of cancer therapy in pediatric patients during therapy and after therapy completion for long-term surveillance. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material See the invited commentary by Ferraciolli and Gee in this issue.

Complications of Cancer Therapy in Children: A Comprehensive Review of Body Imaging Findings

ABSTRACT

Complications of cancer therapy in children can result in a spectrum of toxicities that can affect any organ system and result in a range of morbidity. Complications may occur at the initiation of therapy or years following treatment. Although childhood cancer remains rare, increasing survival rates means more children are living longer following their treatment. Radiologists often play an important role in the diagnosis and evaluation of these complications, and thus, awareness of their imaging findings is essential to guide management and avoid misdiagnosis. This second part of a 2-part review aims to illustrate the typical body imaging findings of cancer therapy-related toxicities, including both early and late treatment effects. The article also discusses the differential diagnosis of imaging findings, highlighting pearls and pitfalls in making the appropriate diagnosis.

Incidental Findings in Pediatric Patients: How to Manage Liver Incidentaloma in Pediatric Patients

The World Federation for Ultrasound in Medicine and Biology (WFUMB) is addressing the issue of incidental findings (IFs) with a series of publications entitled "Incidental imaging findings-the role of ultrasound". IFs in the liver of newborns and children are rare and much less commonly encountered than in adults; as a result, they are relatively much more frequently malignant and life-threatening, even when they are of benign histology. Conventional B-mode ultrasound is the well-established first line imaging modality for the assessment of liver pathology in pediatric patients. US technological advances, resulting in image quality improvement, contrast-enhanced ultrasound (CEUS), liver elastography and quantification tools for steatosis have expanded the use of ultrasound technology in daily practice. The following overview is intended to illustrate incidentally detected liver pathology covering all pediatric ages. It aims to aid the examiner in establishing the final diagnosis. Management of incidentally detected focal liver lesions (FLL) needs to take into account the diagnostic accuracy of each imaging modality, the patient's safety issues (including ionizing radiation and nephrotoxic contrast agents), the delay in diagnosis, the psychological burden on the patient and the cost for the healthcare system. Moreover, this paper should help the pediatric clinician and ultrasound practitioner to decide which pathologies need no further investigation, which ones require interval imaging and which cases require further and immediate diagnostic procedures.

Focal Nodular Hyperplasia-Like Lesions With Glypican-3 Positivity in Infancy

PURPOSE AND CONTEXT

Glypican-3 is often used to discriminate between neoplastic and nonneoplastic liver. In focal lesions, positivity may be considered suggestive of a malignancy such as hepatoblastoma. However, glypican-3 is also normally expressed in the immature liver. We present a series of 5 cases of focal nodular hyperplasia (FNH)-like lesions arising in very young patients with glypican-3 expression and highlight the challenges these lesions present in the differential diagnosis of hepatoblastoma.

METHODS

Cases were obtained from the files of 3 tertiary pediatric hospitals. Clinical data were obtained from the electronic medical record and histopathologic material including immunohistochemical stains were reviewed.

KEY RESULTS

Patients were aged 2 weeks to 6 months with peak AFP levels ranging from 88.6 to 204,696 ng/mL. Microscopically, all were variably demarcated hepatocellular lesions with cords of hepatocytes, marked sinusoidal dilatation, and occasional fibrous bands and areas reminiscent of central scar with bile ducts. No significant cytologic atypia or increased mitotic activity were present. All showed glypican-3 expression and were negative for nuclear beta-catenin with intact reticulin framework.

CONCLUSIONS

Our study highlights the pitfalls of evaluating focal liver lesions in infants when high AFP levels and glypican-3 expression may reflect immaturity rather than neoplasia.

Focal nodular hyperplasia after oxaliplatin-based chemotherapy: A diagnostic challenge

Chemotherapy could induce benign liver alterations presenting as diffuse or focal lesions mimicking metastases. Oxaliplatin-induced vascular liver injury is described in literature, but the association with FNH-like lesions has been reported in a limited number of cases. We herewith describe the case of a 67-year-old male, who had laparoscopic right-sided hemicolectomy, 8 years ago, because of colonic adenocarcinoma (pT3N0M0) and subsequent adjuvant chemotherapy (capecitabine + oxaliplatin), who referred to the ultrasound service of our Radiology Unit because of abdominal pain. Five-years follow-up was negative for metastases. Ultrasound examination showed 2 small hypoechoic hepatic nodules, in segment VIII and VII, confirmed at CT, suspected for metastases. FDG-PET was negative, and blood tumor markers were within normal ranges. For further evaluation we performed gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI that showed hyperintensity of the nodules in the hepatobiliary phase with central small hypointensity due to a central scar. Considering the previous oxaliplatin-based chemotherapy the findings were compatible with FNHlike lesions and the diagnostic suspicion was confirmed at ultrasound-guided core needle biopsy. Knowledge of the possible occurrence of FNH-like lesions in oncologic setting, along with the detection of typical MRI appearance, is important for appropriate management and may avoid unnecessary biopsy or surgery and reduce patients’ anxiety.

Giant focal nodular hyperplasia with a background of hepatic steatosis in a 14-year-old boy

Giant focal nodular hyperplasia (GFNH) is rarely seen in children, presenting complex diagnostic and management considerations. Pathognomonic radiographic findings can be absent in this population, and the nuances of pathologic examination are critical. We present a child with a GFNH involving the right side of the liver arising in the background of hepatic steatosis. The details of the diagnosis and therapeutic decisions involved in his treatment are discussed.

Late hepatic toxicity surveillance for survivors of childhood, adolescent and young adult cancer: Recommendations from the international late effects of childhood cancer guideline harmonization group

BACKGROUND

Survivors of childhood, adolescent and young adult (CAYA) cancer may develop treatment-induced chronic liver disease. Surveillance guidelines can improve survivors' health outcomes. However, current recommendations vary, leading to uncertainty about optimal screening. The International Late Effects of Childhood Cancer Guideline Harmonization Group has developed recommendations for the surveillance of late hepatotoxicity after CAYA cancer.

METHODS

Evidence-based methods based on the GRADE framework were used in guideline development. A multidisciplinary guideline panel performed systematic literature reviews, developed evidence summaries, appraised the evidence, and formulated recommendations on the basis of evidence, clinical judgement, and consideration of benefits versus the harms of the surveillance while allowing for flexibility in implementation across different health care systems.

RESULTS

The guideline strongly recommends a physical examination and measurement of serum liver enzyme concentrations (ALT, AST, gGT, ALP) once at entry into long-term follow-up for survivors treated with radiotherapy potentially exposing the liver (moderate- to high-quality evidence). For survivors treated with busulfan, thioguanine, mercaptopurine, methotrexate, dactinomycin, hematopoietic stem cell transplantation (HSCT), or hepatic surgery, or with a history of chronic viral hepatitis or sinusoidal obstruction syndrome, similar surveillance for late hepatotoxicity once at entry into LTFU is reasonable (low-quality evidence/expert opinion, moderate recommendation). For survivors who have undergone HSCT and/or received multiple red blood cell transfusions, surveillance for iron overload with serum ferritin is strongly recommended once at long-term follow-up entry.

CONCLUSIONS

These evidence-based, internationally-harmonized recommendations for the surveillance of late hepatic toxicity in cancer survivors can inform clinical care and guide future research of health outcomes for CAYA cancer survivors.

Hepatocyte-specific contrast-enhanced MRI findings of focal nodular hyperplasia-like nodules in the liver following chemotherapy in pediatric cancer patients

PURPOSE

We aimed to assess the MRI findings and follow-up of multiple focal nodular hyperplasia (FNH)- like lesions in pediatric cancer patients diagnosed by imaging findings.

METHODS

We retrospectively analyzed clinical data and MRI examinations of 16 pediatric patients, who had been scanned using gadoxetate disodium (n=13) and gadobenate dimeglumine (n=3). Hepatic nodules were reviewed according to their number, size, contour, T1- and T2-weighted signal intensities, arterial, portal, delayed and hepatobiliary phase enhancement patterns. Follow-up images were evaluated for nodule size, number, and appearance.

RESULTS

All 16 patients received chemotherapy in due course. Time interval between the initial diagnosis of cancer and detection of the hepatic nodule was 2-14 years. Three patients had a single lesion, 13 patients had multiple nodules. The median size of the largest nodules was 19.5 mm (range, 8-41 mm). Among 16 patients that received hepatocyte-specific agents, FNH-like nodules appeared hyperintense in 11 and isointense in 5 on the hepatobiliary phase. During follow-up, increased number and size of the nodules were seen in 4 patients. The nodules showed growth between 6-15 mm.

CONCLUSION

Liver MRI using hepatocyte-specific agents is a significant imaging method for the diagnosis of FNH-like lesions, which can occur in a variety of diseases. Lesions can increase in size and number in pediatric patients.

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

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.

Gd-EOB-DTPA MRI for focal nodular hyperplasia-like lesions in pediatric cancer survivors

OBJECTIVES

To investigate the hepatobiliary enhancement patterns of gadoxetic acid (Gd-EOB-DTPA) MRI and the temporal evolution of focal nodular hyperplasia (FNH)-like lesions in pediatric cancer survivors.

METHODS

We retrospectively included pediatric cancer survivors who had new liver lesions detected during surveillance imaging and who were diagnosed with FNH-like lesions by Gd-EOB-DTPA MRI without the aid of a hepatobiliary phase. The hepatobiliary enhancement patterns of FNH-like lesions were categorized as homogeneous hyperintense/isointense, heterogeneous hyperintense, and ring-like enhancement. Temporal changes in the FNH-like lesions were evaluated by follow-up Gd-EOB-DTPA MRI. Statistical analyses included one-way analysis of variance and Spearman's rank correlation test.

RESULTS

A total of 132 radiologically diagnosed FNH-like lesions in 18 patients showed the three different hepatobiliary enhancement patterns: homogeneous hyperintense/isointense (n = 65, 49%), heterogeneous hyperintense (n = 24, 18%), and ring-like enhancement (n = 43, 33%). A weak positive correlation was found between the lesion size and the hepatobiliary enhancement pattern (p = 0.015). Follow-up MRI showed alterations in the size and number of 55 FNHs in 8 patients, including stable size (n = 15, 27%), increased size (n = 17, 31%), decreased size (n = 11, 20%), disappearance (n = 12, 22%), and 74 new lesions (5 patients, 63%).

CONCLUSIONS

FNH-like lesions in pediatric cancer survivors showed three different hepatobiliary enhancement patterns and various temporal changes. Recognition of the radiological characteristics of FNH-like lesions may avoid unnecessary invasive procedures and reduce patients/parents' anxiety.

KEY POINTS

• FNH-like lesions in pediatric cancer survivors showed three different hepatobiliary enhancement patterns. The most common was homogeneous hyperintense/isointense, followed by heterogeneous hyperintense, and ring-like enhancement. • FNH-like lesions in pediatric cancer survivors can show various temporal changes during follow-up.

Contrast-enhanced ultrasound of liver lesions in children

Initial pediatric imaging of the liver heavily relies on ultrasonography (US) because it is free of ionizing radiation, easily portable and readily available. Although conventional US (gray-scale and color Doppler) is often an excellent screening tool, its relative low specificity compared to CT/MRI limits liver lesion characterization. The United States Food and Drug Administration's recent approval of an intravenous US contrast agent for pediatric liver lesion characterization (sulfur hexafluoride lipid-type A microspheres) and its excellent safety profile have spurred increased interest in contrast-enhanced US for definitive diagnosis of pediatric liver lesions. This review focuses on the safety of contrast-enhanced US, role of contrast-enhanced US in the evaluation of focal liver lesions, basic contrast-enhanced US technique for liver imaging, and interpretation principles. The authors review common focal liver lesions, with special attention to the role of contrast-enhanced US in the pediatric oncology population.

Intravenous gadolinium-based hepatocyte-specific contrast agents (HSCAs) for contrast-enhanced liver magnetic resonance imaging in pediatric patients: what the radiologist should know

Hepatocyte-specific contrast agents (HSCAs) are a group of intravenous gadolinium-based MRI contrast agents that can be used to characterize hepatobiliary pathology. The mechanism by which these agents are taken up by hepatocytes and partially excreted into the biliary tree improves characterization of hepatic lesions and biliary abnormalities relative to conventional extracellular gadolinium-based contrast agents (GBCAs). This manuscript presents an overview of HSCA use in pediatric patients with the intent to provide radiologists a guide for clinical use. We review available HSCAs and discuss dosing and age specifications for use in children. We also review various hepatic and biliary indications for HSCA use in children, with emphasis on the imaging characteristics distinct to HSCAs, as well as discussion of pitfalls one can encounter when imaging with HSCAs. Given the growing concern regarding gadolinium deposition in soft tissues and brain, we also discuss safety of HSCA use in children.

Hepatic late adverse effects after antineoplastic treatment for childhood cancer

BACKGROUND

Survival rates have greatly improved as a result of more effective treatments for childhood cancer. Unfortunately, the improved prognosis has been accompanied by the occurrence of late, treatment-related complications. Liver complications are common during and soon after treatment for childhood cancer. However, among long-term childhood cancer survivors, the risk of hepatic late adverse effects is largely unknown. To make informed decisions about future cancer treatment and follow-up policies, it is important to know the risk of, and associated risk factors for, hepatic late adverse effects. This review is an update of a previously published Cochrane review.

OBJECTIVES

To evaluate all the existing evidence on the association between antineoplastic treatment (that is, chemotherapy, radiotherapy involving the liver, surgery involving the liver and BMT) for childhood cancer and hepatic late adverse effects.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2018, Issue 1), MEDLINE (1966 to January 2018) and Embase (1980 to January 2018). In addition, we searched reference lists of relevant articles and scanned the conference proceedings of the International Society of Paediatric Oncology (SIOP) (from 2005 to 2017) and American Society of Pediatric Hematology/Oncology (ASPHO) (from 2013 to 2018) electronically.

SELECTION CRITERIA

All studies, except case reports, case series, and studies including fewer than 10 patients that examined the association between antineoplastic treatment for childhood cancer (aged 18 years or less at diagnosis) and hepatic late adverse effects (one year or more after the end of treatment).

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection and 'risk of bias' assessment. The 'risk of bias' assessment was based on earlier checklists for observational studies. For the original version of the review, two review authors independently performed data extraction. For the update of the review, the data extraction was performed by one reviewer and checked by another reviewer.

MAIN RESULTS

Thirteen new studies were identified for the update of this review. In total, we included 33 cohort studies including 7876 participants investigating hepatic late adverse effects after antineoplastic treatment (especially chemotherapy and radiotherapy) for different types of childhood cancer, both haematological and solid malignancies. All studies had methodological limitations. The prevalence of hepatic late adverse effects, all defined in a biochemical way, varied widely, between 0% and 84.2%. Selecting studies where the outcome of hepatic late adverse effects was well-defined as alanine aminotransferase (ALT) above the upper limit of normal, indicating cellular liver injury, resulted in eight studies. In this subgroup, the prevalence of hepatic late adverse effects ranged from 5.8% to 52.8%, with median follow-up durations varying from three to 23 years since cancer diagnosis in studies that reported the median follow-up duration. A more stringent selection process using the outcome definition of ALT as above twice the upper limit of normal, resulted in five studies, with a prevalence ranging from 0.9% to 44.8%. One study investigated biliary tract injury, defined as gamma-glutamyltransferase (γGT) above the upper limit of normal and above twice the upper limit of normal and reported a prevalence of 5.3% and 0.9%, respectively. Three studies investigated disturbance in biliary function, defined as bilirubin above the upper limit of normal and reported prevalences ranging from 0% to 8.7%. Two studies showed that treatment with radiotherapy involving the liver (especially after a high percentage of the liver irradiated), higher BMI, and longer follow-up time or older age at evaluation increased the risk of cellular liver injury in multivariable analyses. In addition, there was some suggestion that busulfan, thioguanine, hepatic surgery, chronic viral hepatitis C, metabolic syndrome, use of statins, non-Hispanic white ethnicity, and higher alcohol intake (> 14 units per week) increase the risk of cellular liver injury in multivariable analyses. Chronic viral hepatitis was shown to increase the risk of cellular liver injury in six univariable analyses as well. Moreover, one study showed that treatment with radiotherapy involving the liver, higher BMI, higher alcohol intake (> 14 units per week), longer follow-up time, and older age at cancer diagnosis increased the risk of biliary tract injury in a multivariable analysis.

AUTHORS' CONCLUSIONS

The prevalence of hepatic late adverse effects among studies with an adequate outcome definition varied considerably from 1% to 53%. Evidence suggests that radiotherapy involving the liver, higher BMI, chronic viral hepatitis and longer follow-up time or older age at follow-up increase the risk of hepatic late adverse effects. In addition, there may be a suggestion that busulfan, thioguanine, hepatic surgery, higher alcohol intake (>14 units per week), metabolic syndrome, use of statins, non-Hispanic white ethnicity, and older age at cancer diagnosis increase the risk of hepatic late adverse effects. High-quality studies are needed to evaluate the effects of different therapy doses, time trends, and associated risk factors after antineoplastic treatment for childhood cancer.

Hepatobiliary phase liver MR imaging findings after Oxaliplatin-based chemotherapy in cancer patients

OBJECTIVE

To describe Gd-EOB-DTPA-enhanced liver MR imaging findings in colon and rectal cancer patients who received Oxaliplatin.

CONCLUSION

Spectrum of hepatobiliary phase imaging findings include diffuse heterogeneous dysfunction, macronodular and micronodular FNH-like lesions, and coexistence of periportal increased liver function with FNH-like lesions. Differentiation of these benign lesions from metastasis is crucial to avoid biopsy in patients with colorectal cancers and may allow better understanding of sinusoidal obstruction syndrome pathophysiology and regenerative response of liver.

Applications of contrast-enhanced ultrasound in the pediatric abdomen

Contrast-enhanced ultrasound (CEUS) is a radiation-free, safe, and in specific clinical settings, highly sensitive imaging modality. Over the recent decades, there is cumulating experience and a large volume of published safety and efficacy data on pediatric CEUS applications. Many of these applications have been directly translated from adults, while others are unique to the pediatric population. The most frequently reported intravenous abdominal applications of CEUS in children are the characterization of focal liver lesions, monitoring of solid abdominal tumor response to treatment, and the evaluation of intra-abdominal parenchymal injuries in selected cases of blunt abdominal trauma. The intravesical CEUS application, namely contrast-enhanced voiding urosonography (ceVUS), is a well-established, pediatric-specific imaging technique entailing the intravesical administration of ultrasound contrast agents for detection and grading of vesicoureteral reflux. In Europe, all pediatric CEUS applications remain off-label. In 2016, the United States Food and Drug Administration (FDA) approved the most commonly used worldwide second-generation ultrasound contrast SonoVue®/Lumason® for pediatric liver and intravesical applications, giving new impetus to pediatric CEUS worldwide.

ACR Appropriateness Criteria® Suspected Liver Metastases

Liver metastases are the most common malignant liver tumors. The accurate and early detection and characterization of liver lesions is the key to successful treatment strategies. Increasingly, surgical resection in combination with chemotherapy is effective in significantly improving survival if all metastases are successfully resected. MRI and multiphase CT are the primary imaging modalities in the assessment of liver metastasis, with the relative preference toward multiphase CT or MRI depending upon the clinical setting (ie, surveillance or presurgical planning). The optimization of imaging parameters is a vital factor in the success of either modality. PET/CT, intraoperative ultrasound are used to supplement CT and MRI. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

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.

MRI of paediatric liver tumours: How we review and report

Liver tumours are fortunately rare in children. Benign tumours such as haemangiomas and cystic mesenchymal hamartomas are typically seen in infancy, often before 6 months of age. After that age, malignant hepatic tumours increase in frequency. The differentiation of a malignant from benign lesion on imaging can often negate the need for biopsy. Ultrasound is currently the main screening tool for suspected liver pathology, and is ideally suited for evaluation of hepatic lesions in children due to their generally small size. With increasing research, public awareness and parental anxiety regarding radiation dosage from CT imaging, MRI is now unquestionably the modality of choice for further characterisation of hepatic mass lesions.

Nevertheless the cost, length of imaging time and perceived complexity of a paediatric liver MR study can be intimidating to the general radiologist and referring clinician. This article outlines standard MR sequences utilised, reasons for their utilisation, types of mixed hepatocyte specific/extracellular contrast agents employed and imaging features that aid the interpretation of paediatric liver lesions. The two commonest paediatric liver malignancies, namely hepatoblastoma and hepatocellular carcinoma are described. Differentiation of primary hepatic malignancies with metastatic disease and mimickers of malignancy such as focal nodular hyperplasia (FNH) and hepatic adenomas are also featured in this review..

Imaging should aim to clarify the presence of a lesion, the likelihood of malignancy and potential for complete surgical resection. Reviewing and reporting the studies should address these issues in a systematic fashion whilst also commenting upon background liver parenchymal appearances. Clinical information and adequate patient preparation prior to MR imaging studies help enhance the diagnostic yield.

Current role of body MRI in pediatric oncology

Magnetic resonance imaging (MRI) plays an important role in the imaging of children with non-central nervous system malignancies, and it is increasingly replacing or complementing CT in many cases. MRI has several advantages over CT, including superior contrast resolution as well as superior tissue characterization with the use of novel pulse sequences and functional or organ-specific contrast agents. In addition, the lack of ionizing radiation - an important consideration in children - allows for multiphase dynamic post-contrast imaging, which can be useful for lesion detection and characterization. Several challenges remain in the performance of MRI in pediatric oncology patients, including the frequent need for sedation or anesthesia in young children because of long imaging times, as well as the suboptimal imaging of the lungs in the evaluation for pulmonary metastatic disease. However, despite these challenges, with continued improvements in MRI image quality and the development of novel sequences, contrast agents and quantitative imaging techniques, MRI is expected to play an ever increasing role in the imaging of pediatric oncology patients.

Pediatric multifocal liver lesions evaluated by MRI

Objective:

The purpose of this study is to present our experience with MRI evaluation of multifocal liver lesions in children and describe the MRI characteristics of these lesions.

Patients and Methods:

A retrospective review of consecutive MRI exams performed for the evaluation of multiple liver lesions between 1 January 2007 and 31 December 2012 was done to note the number of lesions, the size of the largest lesion, MR signal characteristics, and background liver. Final diagnosis was assigned to each case based on pathology in the available cases and a combination of clinical features, imaging features, and follow-up in the remaining cases.

Results:

A total of 48 children (22 boys, 26 girls; age between 3 months and 18 years with average age 10.58 years and median age 11 years) were included in the study. Totally 51 lesion diagnoses were seen in 48 children that included 17 focal nodular hyperplasia (FNH), 8 hemangiomas, 7 metastases, 6 regenerative nodules, 3 adenomas, 3 abscesses, and one each of angiomyolipoma, epithelioid hemangioendothelioma, focal fatty infiltration, hepatocellular carcinoma, hepatic infarction, nodular regenerative hyperplasia, and hepatic cyst. Background liver was normal in 33, cirrhotic in 10, fatty in 3, and siderotic in 2 children. Most FNH, hemangiomas, and regenerative nodules showed characteristic MRI features, while metastases were variable in signal pattern.

Conclusion:

Many commonly seen multifocal liver lesions in children have characteristic MRI features. MRI can help to arrive at reasonable differential diagnoses for multifocal liver lesions in children and guide further investigation and management.

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.

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

Hepatic focal nodular hyperplasia (FNH) is a nonmalignant condition rarely affecting children previously treated for cancer, especially those who received hematopoietic SCT (HSCT). Some aspects of its pathogenesis still remain unclear and a strong association with specific risk factors has not yet been identified. We report here a single institution's case series of 17 patients who underwent HSCT and were diagnosed with FNH, analyzing retrospectively their clinical features and the radiological appearance of their hepatic lesions. We aimed to compare the diagnostic accuracy of ultrasound (US) and magnetic resonance imaging (MRI) and to explore the role of transient elastography (FibroScan) to evaluate the degree of hepatic fibrosis in FNH patients. Our analysis showed an association of FNH with age at transplant ⩽12 years (hazard ratio (HR) 9.10); chronic GVHD (HR 2.99); hormone-replacement therapy (HR 4.02) and abdominal radiotherapy (HR 4.37). MRI proved to be a more accurate diagnostic tool compared with US. Nine out of 12 patients who underwent FibroScan showed hepatic fibrosis. Our study points out that FNH is an emerging complication of HSCT, which requires a lifelong surveillance to follow its course in cancer patients.

Clinical and imaging features of focal nodular hyperplasia in children

OBJECTIVE

The purpose of this article is to review the clinical and imaging features of focal nodular hyperplasia (FNH) developed in children.

MATERIALS AND METHODS

At a single institution, pediatric patients who underwent imaging studies and who had pathologically proven FNH were studied. Clinical characteristics, including presenting symptoms and signs and the presence of underlying disease, were reviewed from the medical records. Imaging features of FNHs, including the number, size, ultrasound echogenicity and vascularity, CT attenuation, MRI signal intensity and enhancement pattern, and the presence of a central scar, were evaluated.

RESULTS

Twenty-five patients (11 boys and 14 girls; median age, 8.6 years) were found to have a solitary (n = 23) or multiple (n = 2) FNH lesions with a mean size of 4.9 cm (range, 1-10 cm). Multiple lesions were associated with small size of the lesions and history of malignancy treated by chemotherapy. Most patients were asymptomatic (n = 22). Biliary atresia was the most common underlying disease (n = 5). On ultrasound, FNHs most commonly appeared to be isoechoic and hypervascular. On dynamic CT and MRI, strong enhancement on the arterial phase and becoming isoattenuated or of isointense signal intensity on the portal or delayed phase was common. A central scar was usually noted in large lesions in about half the cases.

CONCLUSION

Pediatric FNH is uncommon and usually is found incidentally in otherwise healthy children. However, it may occur in children who have underlying diseases, including biliary atresia. In addition, it can be encountered during surveillance of childhood cancer survivors with less common imaging features, including lack of a central scar and multiplicity.

Dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors

OBJECTIVE

The purpose of this study is to investigate the dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors.

MATERIALS AND METHODS

We reviewed dynamic MRI findings and clinical features in 15 patients who had been treated for childhood malignant solid tumors and in whom hypervascular hepatic nodules were later found on surveillance imaging by either CT or ultrasound (or both). The benign nature of the lesion was based on histologic examination or clinical and radiologic follow-up (or both).

RESULTS

Time between initial diagnosis of malignancy and detection of the hepatic nodule ranged from 4.5 to 13.5 years with the majority of the malignancies being neuroblastoma treated by high-dose chemotherapy and hematopoietic stem cell transplantation. A total of 43 nodules were detected, often multiple and small. Most of the lesions were isointense or slightly hyperintense on T2-weighted imaging and isointense or slightly hypointense on T1-weighted imaging. All nodules had intense enhancement on the arterial phase and were isointense or slightly hyperintense on the delayed phase. A central scar was seen in four. Additionally, hepatic hemosiderosis was noted in four patients, in whom all the lesions were hyperintense on both T1- and T2-weighted imaging.

CONCLUSION

Benign hypervascular hepatic nodules in survivors of childhood malignancy occur years after high-dose chemotherapy and hematopoietic stem cell transplantation. Dynamic MRI findings including intense arterial enhancement and absence of washout in the delayed phase are of great value in the differential diagnosis of these hepatic nodules.

Benign hepatocellular tumors in children: focal nodular hyperplasia and hepatocellular adenoma

Benign liver tumors are very rare in children. Most focal nodular hyperplasia (FNH) remain sporadic, but predisposing factors exist, as follows: long-term cancer survivor (with an increasing incidence), portal deprivation in congenital or surgical portosystemic shunt. The aspect is atypical on imaging in two-thirds of cases. Biopsy of the tumor and the nontumoral liver is then required. Surgical resection will be discussed in the case of large tumors with or without symptoms. In the case of associated vascular disorder with portal deprivation, restoration of the portal flow will be discussed in the hope of seeing the involution of FNH. HepatoCellular Adenoma (HCA) is frequently associated with predisposing factors such as GSD type I and III, Fanconi anemia especially if androgen therapy is administered, CPSS, and SPSS. Adenomatosis has been reported in germline mutation of HNF1- α . Management will depend on the presence of a predisposing factor and may include metabolic control, androgen therapy withdrawn, or closure of the shunt when appropriate. Surgery is usually performed on large lesions. In the case of adenomatosis or multiple lesions, surgery will be adapted. Close followup is required in all cases.