Presence of Fragmented Intratumoral Thrombosed Microvasculature in the Necrotic and Peri‐Necrotic Regions on SWI Differentiates IDH Wild‐Type Glioblastoma From IDH Mutant Grade 4 Astrocytoma
Authors: Yadav Virendra Kumar , Sharma Shalini , Maurya Satyajit , Singh Rakesh K. , Saini Jitendra , Jain Preeti , Patir Rana , Ahlawat Sunita , Das Sumanta , Vaishya Sandeep , Agarwal Sumeet , Singh Anup , Gupta Rakesh K. 
Published: January 2025

BackgroundIsocitrate dehydrogenase (IDH) wild‐type (IDHwt) glioblastomas (GB) are more aggressive and have a poorer prognosis than IDH mutant (IDHmt) tumors, emphasizing the need for accurate preoperative differentiation. However, a distinct imaging biomarker for differentiation mostly lacking. Intratumoral thrombosis has been reported as a histopathological biomarker for GB.PurposeTo evaluate the fragmented intratumoral thrombosed microvasculature (FTV) signs on susceptibility‐weighted imaging (SWI) for distinguishing IDHwt and IDHmt tumors.Study TypeRetrospective.SubjectsNinety‐seven treatment‐naïve patients with histopathologically confirmed IDHwt GB (54 males, 26 females) and IDHmt grade 4 astrocytoma (13 males, 4 females).Field Strength/Sequence3‐T, SWI, fluid‐attenuated‐inversion‐recovery (FLAIR), T1‐weighted, T2‐weighted, PD‐weighted, post‐contrast T1‐weighted and dynamic‐contrast‐enhanced (DCE)‐MRI.AssessmentSWI data were evaluated by three experienced neuroradiologists (S.S., 11 years; J.S., 15 years; R.K.G., 40 years of experience), who assessed FTV presence in necrotic and peri‐necrotic regions. FTV was identified as intratumoral susceptibility signal having minimal or no interslice connections. Quantitative DCE‐MRI parameters were derived using first‐pass‐analysis and extended Tofts model. FLAIR abnormal, contrast‐enhancing, and necrotic regions were segmented using in‐house developed U‐Net architecture.Statistical TestsFleiss' Kappa, Cohen's Kappa, Shapiro–Wilk test, t tests or Mann–Whitney U test, receiver‐operating characteristic (ROC) analysis, confusion matrix. A P‐value <0.05 was considered statistically significant.ResultsFleiss' kappa test provided 91% inter‐rater agreement, and Cohen's kappa provided intrarater agreement ranged from 81% to 97%. The raters' accuracy in distinguishing IDHwt from IDHmt ranged from 92% to 94%. Some of the quantitative DCE‐MRI parameters (CBV, Ve, and Ktrans) provided statistically significant differences in differentiating IDHwt and IDHmt. Ktrans demonstrated 80.3% sensitivity and 81.2% specificity, with ROC analysis showing an AUC of 0.77.Data ConclusionFTV signs in necrotic and peri‐necrotic regions on SWI demonstrated a high accuracy in distinguishing IDHwt from IDHmt. Qualitative assessment of FTV signs showed almost perfect inter‐rater and intrarater agreement. Quantitative DCE‐MRI metrics also showed statistically significant differentiation of IDHwt and IDHmt.Plain Language SummaryThis study demonstrates that preoperative imaging, particularly the visualization of the fragmented thrombosed vasculature (FTV) sign on susceptibility‐weighted imaging (SWI), effectively differentiates isocitrate dehydrogenase (IDH) wild‐type (IDHwt) glioblastoma (GB) from IDH mutant (IDHmt) grade 4 astrocytomas. Over 90% of IDHwt GB patients displayed the FTV sign, a specific imaging biomarker absent in IDHmt cases. Perfusion parameters such as cerebral blood volume, Ve, and Ktrans were elevated in IDHwt gliomas, reflecting distinct vascular profiles. SWI offers a noninvasive and accurate diagnostic method, overcoming limitations of histopathology. Despite limitations like unequal sample sizes and retrospective analysis, this study underscores the clinical potential of SWI in improving glioma characterization and aiding treatment planning.Level of Evidence4Technical EfficacyStage 2