• Tareq A Juratli, Shilpa S Tummala, Angelika Riedl, Dirk Daubner, Silke Hennig, Tristan Penson, Amir Zolal, Christian Thiede, Gabriele Schackert, Dietmar Krex, Julie J Miller, and Daniel P Cahill.
• Translational Neuro-Oncology Laboratory, Department of Neurosurgery, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA.
• J. Neurooncol. 2019 Jan 1; 141 (2): 327-335.

PurposeWith the updated World Health Organization (WHO) 2016 neuropathological diagnostic criteria, radiographic prognostic associations in lower-grade gliomas (LGG, WHO grade II and III) are undergoing re-evaluation.MethodsWe identified 316 LGG patients (151 grade II and 165 grade III) for a combined cohort from three independent databases. We analyzed the preoperative axial FLAIR, axial T2-weighted and post-gadolinium volumetric T1-weighted MR images. The molecular data collected included the status of IDH1/2, TP53, TERT promoter and ATRX mutations, in addition to 1p/19q co-deletions. In a subset of cases (n = 133), we assessed the "T2-FLAIR mismatch" sign.ResultsGliomas were assigned to one of the three molecular groups: Group O (IDH-mutant, 1p/19q co-deleted oligodendrogliomas, n = 95), Group A (IDH-mutant, ATRX inactivated astrocytomas, n = 175) and Group G (IDH wild-type, GBM-like, n = 46). A contrast-enhancing tumor was seen in 98 patients (31%), most frequently in Group G (n = 28/45, 57%), when compared to Group A (n = 49/175, 28%) and Group O (n = 24/95, 25.3%) tumors (p = 0.008 and p = 0.0011, respectively). Consistent with previous reports, T2-FLAIR mismatch was preferentially found in Group A tumors (73.1%, 60 of 82), although its presence was not associated with survival, after controlling for molecular group. False positive mismatch sign was noted in 28.5% (12/42) Group O tumors, but none of the tumors in Group G. A combination of all three factors: age under 40 years at first diagnosis, a tumor size larger than 6 cm and T2-FLAIR mismatch was highly specific for IDH mutant astrocytoma (Group A).ConclusionWe identify radiographic correlates of molecular groups in lower-grade gliomas, which join clinical demographic features in defining the characteristic presentation of these tumors. Radiographic correlates of prognosis in LGG require re-evaluation within molecular group.

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