Purpose or Case Report: Pediatric primary liver tumors, including hepatoblastoma and hepatocellular carcinoma (HCC), are staged according to the PRETEXT system (PRE-Treatment EXTent of Tumor). Although primary hepatic tumors are rare in the pediatric population, hepatoblastoma is increasing in prevalence due to its association with prematurity and the prolonged survival of this patient population. Therefore, it is prudent for radiologists to refamiliarize themselves with these malignancies and how to accurately describe their imaging appearance using descriptors defined by PRETEXT.

Various imaging modalities offer a role in the evaluation of primary hepatic tumors, including ultrasound (US), magnetic resonance (MR), and computed tomography (CT). Contrast enhanced ultrasound (CEUS) is not currently a primary modality but has potential to evaluate vascular involvement and satellite lesions. PRETEXT is the standard to describe a tumor’s imaging features on CT or MR; MR is preferred due to improved soft tissue detail, and emphasis is placed on use of a hepatobiliary contrast agent.

For PRETEXT staging, the liver is divided into four sections: right posterior, right anterior, left medial, and left lateral. Depending on the number of continuous, uninvolved sections, patients are assigned a group ranging from I-IV. Tumors are often large at presentation, and determination of anatomic boundaries can be challenging for the radiologist. Other special circumstances discussed include variant hepatic venous anatomy and pedunculated tumors. PRETEXT also considers “annotation factors”, such as vascular involvement, tumor rupture, and metastases, among others.

In combination with clinical factors, such as the patient's age and alpha-fetoprotein (AFP) level, PRETEXT is also used to stratify patient risk and ultimately influence patient management. If the tumor is not resectable upfront, percutaneous biopsy is recommended to confirm the diagnosis. First line therapy includes surgical resection and systemic chemotherapy. In cases not amenable to this treatment, palliative options offered by pediatric interventional radiology include transarterial chemoembolization (TACE) and percutaneous ablation.

The goal of this educational exhibit is to provide a case-based illustration of PRETEXT staging and annotations factors for the pediatric radiologist.
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