MRI of paediatric liver tumours: How we review and report

Abstract

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.

Liver Transplantation for Pediatric Liver Cancer

“…Today, MRI excels in the detection of vascular invasion by tumor. The capacity of multiple varied MR phases of contrast enhancement including dynamic post contrast three dimensional gradient echo (3D GRE) sequences and delayed hepatobiliary phase, with no additional radiation burden, is a significant reason why MRI is preferred by many radiologists [47]. Others have opted for CT-angiography, especially for large tumors and planning of extreme resections.…”

Pedunculated focal nodular hyperplasia in a healthy toddler

“…If all of the MRI features suggest FNH, a more conservative approach with imaging follow-up may be implemented, whereas if there are atypical features on other sequences in a mass with hepatobiliary phase enhancement, biopsy is warranted. 1,[6][7][8] In the case presented, gadobenate dimeglumine was the formulary hepatobiliary contrast agent available for use, and at the time it was not routinely used in sedated pediatric patients at our institution. Gadobenate dimeglumine has approximately 3% to 5% biliary excretion and requires delayed imaging at 45 to 60 minutes, whereas gadoxetate disodium has approximately 50% biliary excretion and the hepatobiliary phase images are obtained at 20 minutes, making routine delayed imaging with gadoxetate disodium more feasible for sedated pediatric imaging.…”

Pediatric Hepatoblastoma: What the Sonographer Needs to Know for the Sonographic Evaluation of Complications After Treatment and After Liver Transplantation

“…6,7 After diagnosis, staging is usually made with CT, tumor surveillance, and magnetic resonance imaging because of the sensitivity of these imaging modalities. 8,9 Collaboratively, pediatric oncologists and surgeons determine a plan for neoadjuvant chemotherapy and liver tumor resection on the basis of the staging information and imaging examination results. 1 Over the past 2 decades, long-term (5-year) overall survival of patients with HB has improved to <80%, which may be due to the increased use of neoadjuvant chemotherapy to reduce tumor size prior to resection.…”