Abstract
BackgroundThe T2-FLAIR mismatch sign is an imaging finding highly suggestive of isocitrate dehydrogenase mutated (IDH-mut) 1p19q non-codeleted (non-codel) gliomas (astrocytomas). In previous studies, it has shown excellent specificity but limited sensitivity for IDH-mut astrocytomas. Whether the mismatch sign is a marker of a clinically relevant subtype of IDH-mut astrocytomas is unknown.MethodsWe included histopathologically verified supratentorial lower-grade gliomas (LGG) WHO grade II-III retrospectively during the period 2010–2016. In the period 2017–2018, patients with suspected LGG radiologically were prospectively included, and in this cohort other diagnoses than glioma could occur. Clinical, radiological and molecular data were collected. For clinical evaluation we included all patients with IDH-mut astrocytomas. In the 2010–2016 cohort DNA methylation analysis with Infinium MethylationEPIC BeadChip (Illumina) was performed for patients with an IDH-mut astrocytoma with available tissue. We aimed to examine the association of the T2-FLAIR mismatch sign with clinical factors and outcomes. Additionally, we evaluated the diagnostic reliability of the mismatch sign and its relation to methylation profiles.ResultsOut of 215 patients with LGG, 135 had known IDH-mutation and 1p19q codeletion status. Fifty patients had an IDH-mut astrocytoma and 12 of these (24.0%) showed a mismatch sign. The sensitivity and specificity of the mismatch sign for IDH-mut detection were 26.4 and 97.6%, respectively. There were no differences between patients with an IDH-mut astrocytoma with or without mismatch sign when grouped according to T2-FLAIR mismatch sign with respect to baseline characteristics, clinical outcomes and methylation profiles. The overall interrater agreement between neuroradiologist and clinical neurosurgeons for the T2-FLAIR mismatch sign was significant when all 215 MRI examination assessed (κ = 0.77, p < 0.001, N = 215).ConclusionThe T2-FLAIR mismatch sign in patients with an IDH-mut astrocytoma is not associated with clinical presentation or outcome. It seems unlikely that the IDH-mut astrocytomas with mismatch sign represent a specific subentity. Finally, we have validated that the T2-FLAIR mismatch sign is a reliable and specific marker of IDH-mut astrocytomas.
Highlights
The T2-Fluid-attenuated inversion recovery (FLAIR) mismatch sign is an imaging finding highly suggestive of isocitrate dehydrogenase mutated (IDH-mut) 1p19q non-codeleted gliomas
Lower-grade gliomas (LGG) are intra-axial neoplasms of the brain, including WHO grade II and III astrocytomas and oligodendrogliomas according to the WHO 2016 classification and The Cancer Genome Atlas Research Network [1, 2]
We evaluated 58 patients with a suspected LGG
Summary
The T2-FLAIR mismatch sign is an imaging finding highly suggestive of isocitrate dehydrogenase mutated (IDH-mut) 1p19q non-codeleted (non-codel) gliomas (astrocytomas). In previous studies, it has shown excellent specificity but limited sensitivity for IDH-mut astrocytomas. Lower-grade gliomas (LGG) are intra-axial neoplasms of the brain, including WHO grade II and III astrocytomas and oligodendrogliomas according to the WHO 2016 classification and The Cancer Genome Atlas Research Network [1, 2] These subgroups are based upon determination of mutation in the isocitrate dehydrogenase genes 1 or 2 (IDH1 and IDH2), and 1p19q codeletion status [3, 4]. The T2-FLAIR mismatch sign (further referred to as mismatch sign) is characterized by a hyperintense signal on T2-weighted sequences and a hypointense signal on FLAIR sequences with a hyperintense peripheral rim, see Supplementary Figs. 1, 2 and 3 as examples
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