Din Farah,  Hadian Fatemeh,  Chavhan Govind

Final Pr. ID: Poster #: EDU-028

Imaging is crucial in the staging of primary pediatric liver tumors. Hepatoblastoma, pediatric HCC and transitional-type lesions (HCC/hepatoblastoma) should be pre-operatively staged at the time of diagnosis using the PRETEXT system. The PRETEXT (PRE-Treatment EXTent of tumor) criteria were first described in 1992 and updated most recently following an international consensus in 2017, and provide reproducible imaging-based prognostic information for patient survival prior to treatment.

The PRETEXT system consists of two criteria; the group and annotation factors. The PRETEXT stage (I-IV) describes the anatomical extent of tumor within the liver, categorized according to contiguous lesion-free liver sections, whilst the annotation factors describe associated features such as vascular involvement, extrahepatic disease and metastases. These are combined and patients are divided into two risk stratified groups. The standard risk group, mostly including Stage I and II tumors, are more likely to be managed by partial hepatectomy whilst higher risk groups including stage IV tumors are often unresectable and require liver transplantation. Its ultimate goal is to determine the feasibility of surgical resection.

At our institution, our hepatobiliary surgeons use the PRETEXT criteria for prognostication and patient management. International use of these consensus criteria is essential in order to unify management of this rare pediatric tumor subtype.

Our objective is to discuss pearls and pitfalls from our experience of using the PRETEXT criteria. Relevant imaging examples from our large specialist pediatric institute will be provided with discussion of variability of scoring between CT and MRI as well as technical challenges. Selected multi-modality case-based examples will be provided with reference to patient management and operative findings where available. Read More

Authors:  Din Farah , Hadian Fatemeh , Chavhan Govind

Keywords:  Liver tumours, PRETEXT, staging

Lee Samantha,  Cajigas-loyola Stephanie,  Acord Michael

Final Pr. ID: Poster #: EDU-031

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. Read More

Authors:  Lee Samantha , Cajigas-loyola Stephanie , Acord Michael

Keywords:  PRETEXT, Primary Hepatic Tumor, Staging

Guo Chen,  Zhong Yumin,  Zhou Ying,  Hu Li-wei

Final Pr. ID: Poster #: SCI-018

To apply the Couinaud’ system of segmentation and PRETEXT staging system of the liver to the tumor staging, combined with MSCT for evaluate the effectiveness in pre or post therapy of hepatoblatoma. Read More

Authors:  Guo Chen , Zhong Yumin , Zhou Ying , Hu Li-wei

Keywords:  Hepatoblastoma, PRETEXT staging system, Liver

Schoeman Sean,  Venkatakrishna Shyam Sunder,  Silvestro Elizabeth,  Cajigas-loyola Stephanie,  Acord Michael

Final Pr. ID: Poster #: EDU-022

Risk stratification of the most common pediatric primary liver malignancies, hepatoblastoma and hepatocellular carcinoma, is dependent on imaging criteria that ultimately inform work-up and clinical management. The Pediatric Liver Reporting and Data System (LI-RADS) Working Group recommends use of the PRETEXT (PRE-Treatment EXTent of tumor) staging system, which is utilized in the ongoing Pediatric International Tumor Trial (1). PRETEXT staging is first performed by dividing the liver into four sections. Based on how many contiguous sections are free of tumor, a group is assigned from I-IV. Second, annotations factors are assessed depending on the presence of vessel involvement, rupture, multifocality, extrahepatic spread, or metastatic disease, which portend higher risk (2).

Understanding and applying the PRETEXT system should be a core competency for all current and aspiring pediatric radiologists. The PRETEXT system has some barriers to learning, namely in discerning the anatomical liver sections from the functional ‘Couinaud’ segments and accurately determining vessel involvement. We saw the opportunity to combine our diagnostic pediatric radiologic experience/expertise with the application of 3D printing technology. Through the segmentation of post-contrast T1 fat-saturated MRI images, we were able to build 3D models of different PRETEXT stage disease.

The aim of this educational exhibit is to provide pediatric radiologists with an alternative learning tool to appreciate the PRETEXT system and its application. It will combine the proficiency of a 3D pediatric additive manufacturing lab and diagnostic pediatric radiologists with expertise in oncologic imaging and fellowship teaching. Models and their representative 3D renderings will demonstrate the differences between PRETEXT stages, with and without the presence of various annotation factors.

1. Schooler GR, Squires JH, Alazraki A, Chavhan GB, Chernyak V, Davis JT, et al. Pediatric Hepatoblastoma, Hepatocellular Carcinoma, and Other Hepatic Neoplasms: Consensus Imaging Recommendations from American College of Radiology Pediatric Liver Reporting and Data System (LI-RADS) Working Group. Radiology. 2020 Sep;296(3):493–7.
2. Towbin AJ, Meyers RL, Woodley H, Miyazaki O, Weldon CB, Morland B, et al. 2017 PRETEXT: radiologic staging system for primary hepatic malignancies of childhood revised for the Paediatric Hepatic International Tumour Trial (PHITT). Pediatr Radiol. 2018 Apr;48(4):536–54. Read More

Authors:  Schoeman Sean , Venkatakrishna Shyam Sunder , Silvestro Elizabeth , Cajigas-loyola Stephanie , Acord Michael

Keywords:  PRETEXT Staging, 3D Printing, MRI