Correlating MRI features with additional genetic markers and patient survival in histological grade 2-3 IDH-mutant astrocytomas

Abstract

Purpose The increasing importance of molecular markers for classification and prognostication of diffuse gliomas has prompted the use of imaging features to predict genotype (“radiogenomics”). CDKN2A/B homozygous deletion has only recently been added to the diagnostic paradigm for IDH[isocitrate dehydrogenase]-mutant astrocytomas; thus, associated radiogenomic literature is sparse. There is also little data on whether different IDH mutations are associated with different imaging appearances. Furthermore, given that molecular status is now generally obtained routinely, the additional prognostic value of radiogenomic features is less clear. This study correlated MRI features with CDKN2A/B status, IDH mutation type and survival in histological grade 2-3 IDH-mutant brain astrocytomas. Methods Fifty-eight grade 2–3 IDH-mutant astrocytomas were identified, 50 with CDKN2A/B results. IDH mutations were stratified into IDH1-R132H and non-canonical mutations. Background and survival data were obtained. Two neuroradiologists independently assessed the following MRI features: T2-FLAIR mismatch (<25%, 25–50%, >50%), well-defined tumour margins, contrast-enhancement (absent, wispy, solid) and central necrosis. Results 8/50 tumours with CDKN2A/B results demonstrated homozygous deletion; slightly shorter survival was not significant (p=0.571). IDH1-R132H mutations were present in 50/58 (86%). No MRI features correlated with CDKN2A/B status or IDH mutation type. T2-FLAIR mismatch did not predict survival (p=0.977), but well-defined margins predicted longer survival (HR 0.36, p=0.008), while solid enhancement predicted shorter survival (HR 3.86, p=0.004). Both correlations remained significant on multivariate analysis. Conclusion MRI features did not predict CDKN2A/B homozygous deletion, but provided additional positive and negative prognostic information which correlated more strongly with prognosis than CDKN2A/B status in our cohort.

DSC-PWI presurgical differentiation of grade 4 astrocytoma and glioblastoma in young adults: rCBV percentile analysis across enhancing and non-enhancing regions

“…As an addition, just to reinforce our observations that these two tumors display similar characteristics on morphological imaging, we referred to the most recent research [8][9][10][11][12][13]. According to these studies, the primary imaging markers for IDH-mutation status on morphological MRI might include nodular enhancement, necrosis, and T2-FLAIR mismatch.…”

“…The challenge of radiologically distinguishing between these two entities is highlighted by the morphological evaluations in this study, as illustrated in Fig. 2; Table 2, when considering the main markers described for differentiating between IDH-mutant and IDH-wildtype tumors [8][9][10][11][12][13].…”

“…While lower-grade IDHmutant astrocytomas typically appear as non-enhancing and non-necrotic on morphological images, grade 4 astrocytomas can mimic the imaging characteristics of glioblastomas. Both often exhibit enhancement and necrosis, contrasting starkly with their grade 2-3 IDH-mutant counterparts [7][8][9][10][11][12][13]. This overlap in morphological features between IDH-mutant and IDH-wildtype grade 4 tumors highlights the need for advanced quantitative MR techniques, such as Dynamic-Susceptibility-Contrast Perfusion-Weighted-Imaging (DSC-PWI).…”