Pediatric Hepatoblastoma After Neoadjuvant Chemotherapy: Diagnostic Performance of MR in Staging POSTTEXT and Vascular Involvement

Abstract

Background: The assessment of resectability after neoadjuvant chemotherapy of hepatoblastoma is dependent on Post-Treatment EXTENT of Disease (POSTTEXT) staging and its annotation factors P (portal venous involvement) and V (hepatic venous/inferior vena cava [IVC] involvement), but MR performance in assessing them remains unclear.

Purpose: To assess the diagnostic performance of contrast-enhanced MR imaging for preoperative POSTTEXT staging and diagnosing vascular involvement in terms of annotation factors P and V in pediatric hepatoblastoma following neoadjuvant chemotherapy.

Study type: Retrospective.

Subjects: Thirty-five consecutive patients (17 males, median age, 24 months; age range, 6-98 months) with proven hepatoblastoma underwent preoperative MR imaging following neoadjuvant chemotherapy.

Field strength/sequence: 3.0 T; T2-weighted imaging (T2WI), T2WI with fat suppression, diffusion weighted imaging, radial stack-of-the-star/Cartesian 3D Dixon T1-weighted gradient echo imaging.

Assessment: Three radiologists independently assessed the POSTTEXT stages and annotation factors P and V based on the 2017 PRE/POSTTEXT system. The sensitivities and specificities were calculated for 1) diagnosing each POSTTEXT stage; 2) discrimination of stages III and IV (advanced) from those stages I and II (non-advanced) hepatoblastomas; and 3) annotation factors P and V. The combination of pathologic findings and surgical records served as the reference standard.

Statistical tests: Sensitivity, specificity, Fleiss kappa test.

Results: The sensitivity and specificity ranges for discriminating advanced from non-advanced hepatoblastomas were 73.3%-80.0% and 80.0%-90.0%, respectively. For annotation factor P, they were 66.7%-100.0% and 90.6%, respectively. For factor V, they were 75.0% and 67.7%-83.9%, respectively. There was excellent, substantial, and moderate agreement on POSTTEXT staging (Fleiss kappa = 0.82), factors P (Fleiss kappa = 0.64), and factors V (Fleiss kappa = 0.60), respectively.

Data conclusion: MR POSTTEXT provides reliable discrimination between advanced and non-advanced tumors, and MR has moderate to excellent specificity at identifying portal venous and hepatic venous/IVC involvement.

Evidence level: 3 TECHNICAL EFFICACY: Stage 3.

Keywords: POSTTEXT; hepatoblastoma; magnetic resonance imaging; resectability.