Looking through the imaging perspective: the importance of imaging necrosis in glioma diagnosis and prognostic prediction

Purpose: To investigated the diagnostic value of imaging necrosis (Im necrosis ) in grading, predicting the genotype and prognosis of gliomas, and further assessed the association of tumor necrosis and hypoxia, which was assessed by dynamic contrast-enhanced MR perfusion imaging (DCE-MRI). Materials and Methods We retrospectively included 150 (46 females, mean age: 46 years old) pathologically proved adult diffuse gliomas, and all diagnosis based on the 2021 WHO CNS classification. The pathological necrosis (Pa necrosis ) and gene mutation information (IDH, 1p19q, EGFR amplification, chr7 gain/10 loss, CDKN2A/B) was collected. All patients underwent conventional (T1WI, T2WI, FLAIR) and DCE-MRI examinations, and has been followed until May 31, 2021.The Im necrosis was determined by two expericed neuroradiologists. DCE-MRI derived metric ( ktrans , ve , kep and iauc ) maps have been postprocessed and the mean value of each metric in the tumor parenchy, peritumoral and contralateral area were recorded. Various statistical analyses such as survival analysis were performed. Results There was a strong degree of inter-observer agreement in defining Im necrosis (Kappa = 0.668, p  < 0.001), and a strong degree of agreement between Im necrosis and Pa necrosis (Kappa = 0.767, p  < 0.001). Compared to low-grade gliomas, high-grade gliomas had more Im necrosis (85.37%, p  < 0.001), and Im necrosis significantly increased with the grade of gliomas increasing ( p  < 0.001). And Im necrosis was significantly more identified in IDH-wildtype, 1p19q-non-codeletion, and CDKN2A/B-homozygous-deletion gliomas (all p  < 0.01). Using multivariate Cox regression analysis, Im necrosis was an independent and unfavorable prognosis factor (Hazard Ratio = 2.113, p  = 0.046) in gliomas. Additionally, ve in tumor parenchyma derived from DCE-MRI demonstrated the highest diagnostic efficiency in identifying Pa necrosis and Im necrosis with high specificity (83.3% and 91.9%, respectively). Conclusions Im necrosis can provide supplementary evidence beyond Pa necrosis in grading, predicting the genotype and prognosis of gliomas, and tumor parenchyma ve can help to predict tumor necrosis with high specificity.