MR Imaging of Pediatric Low-Grade Gliomas: Pretherapeutic Differentiation of<i>BRAF</i>V600E Mutation,<i>BRAF</i>Fusion, and Wild-Type Tumors in Patients without Neurofibromatosis-1
Andrew Trasolini, Craig Erker, Sylvia Cheng, Cameron Crowell, Kathryn McFadden, Rahim Moineddin, Michael A. Sargent, Daddy Mata‐Mbemba
Abstract
<h3>BACKGROUND AND PURPOSE:</h3> The prognosis and treatment of pediatric low-grade gliomas is influenced by their molecular subtype. MR imaging remains the mainstay for initial work-up and surgical planning. We aimed to determine the relationship between imaging patterns and molecular subtypes of pediatric low-grade gliomas. <h3>MATERIALS AND METHODS:</h3> This was a retrospective bi-institutional study for patients diagnosed from 2004 to 2021 with pathologically confirmed pediatric low-grade gliomas molecularly defined as <i>BRAF</i> fusion, <i>BRAF</i> V600E mutant, or wild-type (which is neither <i>BRAF</i> V600E mutant nor <i>BRAF</i> fusion). Two neuroradiologists, blinded, independently reviewed imaging parameters from diagnostic MRIs, and discrepancies were resolved by consensus. Bivariate analysis was used followed by pair-wise comparison of the Dwass-Steel-Critchlow-Fligner method to compare the 3 molecular subtypes. Interreader agreement was assessed using κ. <h3>RESULTS:</h3> We included 70 patients: 30 <i>BRAF</i> fusion, 19 <i>BRAF</i> V600E mutant, and 21 wild-type. There was substantial agreement between the readers for overall imaging variables (κ = 0.75). <i>BRAF</i> fusion tumors compared with <i>BRAF</i> V600E and wild-type tumors were larger (<i>P</i> = .0022), and had a greater mass effect (<i>P</i> = .0053), increased frequency of hydrocephalus (<i>P</i> = .0002), and diffuse enhancement (<i>p</i> <.0001). <i>BRAF</i> V600E mutant tumors were more often hemispheric (<i>P </i>< .0001), appeared more infiltrative (<i>P</i> = .0002), and, though infrequent, were the only group demonstrating diffusion restriction (qualitatively; <i>P</i> = .0042) with a lower ADC ratio (quantitatively) (<i>P</i> = .003). <h3>CONCLUSIONS:</h3> <i>BRAF</i> fusion and <i>BRAF</i> V600E mutant pediatric low-grade gliomas have unique imaging features that can be used to differentiate them from each other and wild-type pediatric low-grade glioma using a standard radiology review with high interreader agreement. In the era of targeted therapy, these features can be useful for therapeutic planning before surgery.