Radiol Oncol 2024; 58(1): 23-32. doi: 10.2478/raon-2024-0014 23 research article Looking through the imaging perspective: the importance of imaging necrosis in glioma diagnosis and prognostic prediction − single centre experience Hui Ma, Shanmei Zeng, Dingxiang Xie, Wenting Zeng, Yingqian Huang, Liwei Mazu, Nengjin Zhu, Zhiyun Yang, Jianping Chu, Jing Zhao Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China Radiol Oncol 2024; 58(1): 23-32. Received 19 September 2023 Accepted 01 December 2023 Correspondence to: Zhao Jing, Chu Jianping and Yang Zhiyun, Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, No. 58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, People’s Republic of China. E-mail: zhaoj23@mail.sysu.edu.cn Ma Hui, Zeng Shanmei and Xie Dingxiang contributed equally. Disclosure: No potential conflicts of interest were disclosed. This is an open access article distributed under the terms of the CC-BY license (https://creativecommons.org/licenses/by/4.0/). Background. The aim of the study was to investigate the diagnostic value of imaging necrosis (Imnecrosis) in grading, predict the genotype and prognosis of gliomas, and further assess tumor necrosis by dynamic contrast-enhanced MR perfusion imaging (DCE-MRI). Patients and methods. We retrospectively included 150 patients (104 males, mean age: 46 years old) pathologi- cally proved as adult diffuse gliomas and all diagnosis was based on the 2021 WHO central nervous system (CNS) clas- sification. The pathological necrosis (Panecrosis) and gene mutation information were collected. All patients underwent conventional and DCE-MRI examinations and had been followed until May 31, 2021. The Imnecrosis was determined by two experienced neuroradiologists. DCE-MRI derived metric maps have been post-processed, and the mean value of each metric in the tumor parenchyma, peritumoral and contralateral area were recorded. Results. There was a strong degree of inter-observer agreement in defining Imnecrosis (Kappa = 0.668, p < 0.001) and a strong degree of agreement between Imnecrosis and Panecrosis (Kappa = 0.767, p < 0.001). Compared to low-grade gliomas, high-grade gliomas had more Imnecrosis (85.37%, p < 0.001), and Imnecrosis significantly increased with the grade of gliomas increasing. And Imnecrosis was significantly more identified in IDH-wildtype, 1p19q-non-codeletion, and CDKN2A/B-homozygous-deletion gliomas. Using multivariate Cox regression analysis, Imnecrosis was an independent and unfavorable prognosis factor (Hazard Ratio = 2.113, p = 0.046) in gliomas. Additionally, extravascular extracellular volume fraction (ve) in tumor parenchyma derived from DCE-MRI demonstrated the highest diagnostic efficiency in identifying Panecrosis and Imnecrosis with high specificity (83.3% and 91.9%, respectively). Conclusions. Imnecrosis can provide supplementary evidence beyond Panecrosis in grading, predicting the genotype and prognosis of gliomas, and ve in tumor parenchyma can help to predict tumor necrosis with high specificity. Key words: glioma; necrosis; MRI; molecular markers; prognosis Introduction Necrosis is a common feature of human cancer and is often related to a poor prognosis, especially in glioblastomas.1-3 Though the importance of necro- sis in gliomas has already been addressed, necro- sis was first incorporated into the determinant of the diagnosis for glioma grade in the fifth edition of the 2021 WHO classification of Tumors of the central nervous system (CNS), which highlighted Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction24 and underlined the significant value of necrosis in the diagnosis and prognosis of adult diffuse glio- mas.4 According to the latest classification, once histological necrosis is identified, a diagnosis of WHO grade 4 astrocytoma or glioblastoma is sug- gested. However, there is a diagnostic dilemma in grading gliomas by identifying necrosis. Presently, necrosis is primarily determined by pathological examination, in which partial tumor specimens from specific sites of tumors obtained by surgery or biopsy at a single point in time are generally inspected.5 However, due to tumor het- erogeneity and incompleteness of the pathological sample, some pathological necrosis is likely to be missed, which may result in an underestimation of tumor grades, especially when the molecular analysis is not available. As tumor grades influ- ence therapeutic decisions and prognosis, it is im- perative to make up for the problem of a missed diagnosis of necrosis on pathological evaluation. Magnetic resonance imaging (MRI) is utilized for routine, noninvasive, preoperative examina- tion in diagnosing gliomas. Pathological necrosis usually has corresponding imaging features.6,7 Imaging necrosis has been defined as a region within the tumor that does not enhance or shows markedly diminished enhancement, high signal intensity on T2WI, low signal intensity on T1WI, and an irregular border.6 Hence necrosis in glio- mas, when substantially present, can be detected by conventional MRI and plays a vital role in di- agnosing gliomas and predicting prognosis.6,8-13 Moreover, conventional and advanced MRI can acquire comprehensive morphological and patho- physiological images of entire tumors, which is im- possible with pathological examinations. Taking all of this into account, we speculated whether necrosis diagnosed by MRI (hereaf- ter termed “imaging necrosis”, abbreviated as Imnecrosis) could be used as a correction or a supple- ment to necrosis diagnosed by pathological evalu- ation (hereafter termed “pathological necrosis”, abbreviated as Panecrosis), especially when there is no evidence of Panecrosis owing to limited sampling sites and sampling amounts. Consequently, here- in, we retrospectively reviewed MRI findings of adult diffuse gliomas that were diagnosed based on the 2021 WHO CNS classification and assessed the role of Imnecrosis in grading, predicting the geno- type and prognosis of gliomas. We also attempted to analyse tumor necrosis by dynamic contrast- enhanced MR perfusion imaging (DCE-MRI) to validate quantitative imaging markers for probing tumor necrosis. Patients and methods Study participants Patients with a primary diagnosis of glioma (June 2013–May 2021) were retrospectively included. Inclusion and exclusion criteria are presented in Supplementary Figure 1. Clinical information of patients was retrieved from the electronic medical records, and follow-up information was obtained through clinical interviews. Follow-up survival data were available until May 31, 2021. Overall survival (OS) was calculated from the initial sur- gery date to the date of death, or the date of the last follow-up visit if the patient was alive or lost to follow-up. This retrospective analysis was in accordance with the ethical standards of the institutional and national research committee and was approved by the ethics committee of our institution ([2021]209). The requirement for written informed consent was waived due to the retrospective nature of this study. MRI parameters Participants underwent conventional (T1/T2- weighted images [T1WI/T2WI], T2-weighted fluid- attenuated inversion recovery [T2WI-FLAIR] and sagittal view of contrast-enhanced three-dimen- sional T1 MPRAGE images) and DCE-MRI imag- ing using a 3.0T MR system (Magnetom Verio, Siemens Medical Solutions, Erlangen, Germany) with a 64-channel head-neck coil. The parameter details of the conventional MRI and the DCE-MRI were elaborated in Supplementary Appendix 1. Image processing All DCE-MRI data were transferred to the post- processing workstation (detailed in Supplementary Appendix 2). Pharmacokinetic parameters, includ- ing the transfer constant (ktrans), extravascular extracellular volume fraction (ve), rate constant (kep = ktrans/ve), and initial area under the curve in the first 60 s (iauc), were automatically generat- ed. Regions of interest (ROIs) were selected across three consecutive maximum tumor parenchyma slices. At each slice, one ROI was put in tumor parenchyma (hereafter termed “tumor”), accord- ing to T2WI-FLAIR, and enhanced T1WI, avoiding necrosis, cystic, and vessel areas. Another two ap- proximate 2-mm-diameter ROIs were put in tumor peripheral zones (hereafter termed “edema”, with- in a 1-cm distance from the outer enhancing tumor Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction 25 margin) and contralateral normal-appearing brain tissues (hereafter termed “control”) (Figure 1). The mean values of each DCE-MRI metric was record- ed. As mentioned in the introduction, examples of imaging necrosis, defined as a region within the tumor that does not enhance or shows mark- edly diminished enhancement, high signal inten- sity on T2WI, low signal intensity on T1WI, and an irregular border, are shown in Figure 2 and Supplementary Figure 2. Two experienced radiolo- gists reviewed all conventional MRIs. Then they determined whether there was Imnecrosis by consen- sus. One of these two experienced radiologists and a third radiologist repeatedly assessed 68 cases after the initial assessment to assess the inter-ob- server agreement. The assessed images were ran- domized within each type of pathology, and the observers were blinded to the clinical and patho- logical information and thoroughly acquainted with the criteria. Pathological and molecular analysis Panecrosis was defined according to pathological re- ports provided by the Pathology department of our hospital, if available. The status of 1p19q codele- tion, EGFR amplification, chr7 gain/10 loss (+7/-10), and CDKN2A/B homozygous deletion were deter- mined by fluorescence in situ hybridization with a specific probe. IDH mutation was determined by high-throughput sequencing, including IDH1 and IDH2 mutations. The pathological diagnosis and grading of gliomas were reassigned according to the 2021 WHO CNS classification (Supplementary Figure 3).4,14,15 Statistical analysis Statistical Analysis Data were analyzed using IBM SPSS Statistics 26 software, the SPSSAU data sci- entific analysis platform (https://spssau.com/), and the R programming language (version 4.1.2, The R Foundation for Statistical Computing). Normally distributed continuous variables were compared using unpaired t-tests, whereas non-parametric tests were used for non-normally distributed vari- ables. Descriptive data are expressed as mean ± SD, except where otherwise stated. Unpaired t-tests, non-parametric tests, and chi-squared tests were used to compare differences between parameters. Receiver Operating Characteristics (ROC) curves FIGURE 1. Representative ROI delineations. A 53-year-old man was diagnosed with glioblastoma, IDH-wildtype. (A) contrast- enhanced T1-weighted image (T1WI-CE); (B) the time-signal intensity curve; (C) the transfer constant (ktrans) image; (D) rate constant (kep) image; (E) extravascular extracellular volume fraction (ve) image; (F) initial area under the curve in the first 60 s (iauc) image. On images, B-F, ROI 1 marked green represented tumor parenchyma, ROI 2 marked yellow represented the peripheral zones, and ROI 3 marked blue-turquoise represented contralateral normal-appearing brain tissues. A B C D E F Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction26 were used to evaluate diagnostic efficacy. Simple kappa was calculated to assess the consistency of different diagnoses and inter-observer agreement. Kaplan–Meier survival analysis was used to ana- lyze survival data. Hazard ratios (HR) were esti- mated according to the Cox proportional hazard method. A two-sided p value < 0.05 was considered significant. Detailed statistical methods are shown in Supplementary Appendix 3. Results Patients’ demographic and clinical findings We initially identified 150 eligible patients (median age = 46 years, range 21–79 years), and 104 (69.33%) were male (Table 1). All the diagnoses assigned to the patients according to the latest integrated his- to-molecular classification criterion were present- ed in Supplementary Figure 3 and Supplementary Table 1. Panecrosis was identified in 70/76 of high- grade gliomas (HGGs, CNS WHO grade 4) and 3/43 of low-grade gliomas (LGGs, CNS WHO grade 2 and 3) which were oligodendrogliomas, IDH- mutant and 1p/19q-deleted, while Imnecrosis was identified in 70/76 of HGGs and 12/43 of LGGs. There was 1/77 HGG without enhancement but with positive status of EGFR amplification, thus diagnosed as glioblastomas, IDH-wildtype, while there were 32/45 LGGs with enhancement diagnosed as oligodendrogliomas, IDH-mutant and 1p/19q-deleted (n = 15) and astrocytoma, IDH-mutant (n = 17). And most HGGs were mani- fested as ring enhancement, and most LGGs had patchy and punctate enhancement. All the clini- cal information was presented in Table 1 and Supplementary Appendix 4. Interobserver agreement of imaging necrosis and correlation between imaging and pathological necrosis In this study, the following four groups were de- termined: Im+Panecrosis group (representing patients with both Imnecrosis and Panecrosis, n = 74), nonecrosis group (representing patients without Imnecrosis nor Panecrosis, n = 28), Only Imnecrosis group (represent- ing patients with Imnecrosis but without Panecrosis, n = 7), and Only Panecrosis group (representing patients with Panecrosis but without Imnecrosis, n = 4) groups. Detailed clinical, imaging and paychological in- formation of Only Imnecrosis group and Only Panecrosis group were shown in Table 2. We found strong agreement between Imnecrosis and Panecrosis (Kappa = 0.767, p < 0.001, 95%CI: 0.637–0.897). Besides, there was strong inter-observer agree- ment in identifying imaging necrosis (Kappa = 0.668, p < 0.001, 95%CI: 0.489–0.846). And the spot- like, dotted, long-strip, long tubular, and fissural enhancements (Figure 3) which were easily mis- diagnosed as imaging necrosis should be avoided. Association of imging necrosis with integrated glioma grading Most HGGs (85.37%) were found to have Imnecrosis, while most LGGs (83.78%) were without Imnecrosis. There were 4/30 WHO grade 2 patients with Imnecrosis. Of those, two were diagnosed as oligo- dendrogliomas, IDH-mutant and 1p/19q-deleted, and two as astrocytomas, IDH-mutant. Significant differences in the presence of Imnecrosis with a large effect size were found between HGGs and LGGs and among different grades of glio- mas (Table 1, p < 0.001). Cochran–Armitage tests showed an upward trend in Imnecrosis from lower to higher grades of gliomas (p < 0.001). Multiple comparisons with Bonferroni correction showed that the difference between WHO grades (any two grades) and Imnecrosis was significant (all p < 0.01). Association of imaging necrosis and molecular profiles of gliomas There were significant correlations between the expression of other molecular markers such as IDH, 1p19q, and CDKN2A/B and the presence of Imnecrosis. According to Table 1, the proportion of IDH-wildtype, 1p19q-non-codeletion, or CDKN2A/ B-positive cases with Imnecrosis was significantly higher than that of cases without Imnecrosis with a medium effect size, respectively (75.82% vs. A B C FIGURE 2. Representative MR images with imaging necrosis derived from a 53-year-old man with glioblastoma, IDH-wildtype. Shown from left to right by the order are T1WI (A), T2WI (B), and T1WI-CE (C). Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction 27 32.08%, 85.94% vs. 51.11%, 20% vs. 0, respectively). However, no significant correlation was found be- tween Imnecrosis and EGFR amplification or +7/-10 cytogenetic signature (p > 0.05) (Table 1). Association of imaging necrosis with patient prognosis One-hundred and thirty patients were included in the final survival analysis. Compared with gliomas with Imnecrosis, patients without Imnecrosis had a significantly longer survival time (p < 0.001, Figure 4A). By reference to the gliomas with Panecrosis, patients without Panecrosis had a sig- nificantly longer survival time as well (p < 0.001, Figure 4B). The differences among the OS of Im+Panecrosis, nonecrosis, Only Imnecrosis, and Only Panecrosis groups were statistically significant (p < 0.01, Figure 4C). Further, after Bonferroni correction, there were significant differences between Im+Panecrosis and nonecrosis groups (p < 0.001). According to Figure 4C, the OS of the Only Panecrosis group (n = 2) was short- er than the OS of nonecrosis group (n = 28) and Only Imnecrosis group (n = 7). Between the two survival curves of nonecrosis and the Only Imnecrosis groups, there were marked crossovers, but within a cer- tain period (time spanning about from 5-month TABLE 1. Participant demographic findings Parameters Type Imaging necrosis Sum t/χ2b pNegative n (%) Positive n (%) Age (n = 150) - 40.54±11.08(n = 54) 50.39±12.47 (n = 96) - -4.829& p < 0.001 Sex (n = 150) male 36(66.67) 68(70.83) 104 0.282 0.595 female 18(33.33) 28(29.17) 46 IDH (n = 144) wildtype 17(32.08) 69(75.82) 86 26.649 p < 0.001 mutant 36(67.92) 22(24.18) 58 1p19q (n = 109) non-codeletion 23(51.11) 55(85.94) 78 15.746 p < 0.001 codeletion 22(48.89) 9(14.06) 31 CDKN2A/B homozygous deletion (n = 63) non-deletion 38(100.00) 20(80.00) 58 5.745b 0.017* deletion 0(0.00) 5(20.00) 5 EGFR amplification (n = 81) non-amplification 8(66.67) 45(65.22) 53 0.054a 0.817 amplification 4(33.33) 24(34.78) 28 chr7 gain/10 loss (n = 26) negative 10(83.33) 13(92.86) 23 0.552b 0.457 positive 2(16.67) 1(7.14) 3 Grade (n = 119) high-grade 6(16.22) 70(85.37) 76 52.828 p < 0.001 low-grade 31(83.78) 12(14.63) 43 WHO grade (n = 119) WHO grade 2 26(70.27) 4(4.88) 30 62.664a p < 0.001WHO grade 3 5(13.51) 8(9.76) 13 WHO grade 4 6(16.22) 70(85.37) 76 Integrated histo-molecular diagnoses (n = 116) Oligodendroglioma, IDH-mutant and 1p/19q-deleted 17(45.95) 7(8.86) 24 41.238 p < 0.001Astrocytoma, IDH-mutant 15(40.54) 12(15.19) 27 Glioblastoma, IDH-wildtype 5(13.51) 60(75.95) 65 & = Student’s t statistic in this cell, and other cells in the same column represent Chi-square values. a and b = chi-square tests with continuity correction and Fisher’s exact tests, respectively; * = p < 0.05 Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction28 to 40-month postoperatively), the OS of the Only Imnecrosis group was shorter than the OS of nonecrosis group. Further, when added significant variables such as age, IDH, 1p19q, and Imnecrosis into the multivari- ate Cox proportional hazards regression analyses, only Imnecrosis (HR = 2.113, 95% CI: 1.015–4.402, p = 0.046) was significant and independently related to the patients’outcome, indicating that Imnecrosis is an independent and unfavourable prognostic fac- tor. Correlation of tumor necrosis and DCE- MRI metrics Since pathology is the golden standard for necro- sis diagnosis, we analyzed the associations with Panecrosis and DCE-MRI metrics. Most DCE-MRI metrics demonstrated a significant difference in identifying gliomas with Panecrosis with a very large effect size (Table 3). Kep was significantly higher for gliomas with Panecrosis than those with- out Panecrosis, while other DCE-MRI metrics showed the opposite trend. ROCs analysis showed that the Tumor-ve-Mean displayed the best diagnostic performance with the largest AUC of 0.891 (95%CI: 0.788–0.995, p < 0.0001), and the optimal cut-off point was 0.17 with a sensitivity of 96% and speci- ficity of 83.3%. Similarly, we performed the analysis regard- ing Imnecrosis (Table 3), and the Tumor-ve-Mean dis- played the best diagnostic performance as well, with the most significant AUC of 0.929 (95%CI: 0.872–0.986, p < 0.0001) and the optimal cut-off point was 0.17 with a sensitivity of 89.2% and spec- ificity of 91.9%. Discussion In this study, we investigated the clinical impli- cation of imaging necrosis in the preoperative evaluation of glioma. We found strong agreement between Imnecrosis and Panecrosis. Moreover, Imnecrosis was found to be significantly related to glioma- related key gene mutations, such as 1p19q non- codeletion and CDKN2A/B homozygous deletion. And it is an independent imaging marker for pre- dicting tumor prognosis. Additionally, tumor pa- renchyma ve derived from DCE-MRI can help to predict tumor necrosis with high specificity. Our study indicated strong agreement between the inter-observer agreement of Imnecrosis and Panecrosis. And during the analysis, we found that A B C D E FIGURE 3. Some representative MRI images without imaging necrosis which was exactly confused in diagnosing imaging necrosis. Shown from left to right by the order are T1WI, T2WI, and T1WI-CE. (A) a 24-year-old man with an oligodendroglioma, IDH-mutant and 1p/19q-deleted, CNS WHO grade 2; (B) a 39-year-old man with an oligodendroglioma, IDH-mutant and 1p/19q-deleted, CNS WHO grade 2; (C) a 55-year-old woman with an oligodendroglioma, IDH- mutant and 1p/19q-deleted, CNS WHO grade 2; (D) a 45-year-old man with an astrocytoma, CNS IDH-mutant, WHO grade 2; (E) a 36-year-old woman with an oligodendroglioma, IDH-mutant and 1p/19q-deleted, CNS WHO grade 2. In this case (E), it showed multiple long tubular and filiform enhancement and there were some tumor areas with remarked decrease of reinforcement. But these areas are hyperintense, not hypointense, on the T1-weighted image. Comparing with CT images (not provided), calcification on these areas were just observed. So, there was no imaging necrosis in these conditions. Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction 29 the regions with an absence or marked decrease of enhancement inside the intensified areas were easily mistaken as Imnecrosis. While considering pathological samples were partial, imaging obser- vation can capture full tumors. There was a patho- logically proven astrocytoma, IDH-mutant, CNS WHO grade 2, with a very short OS (5 months). We reviewed the raw data and identified that this pa- tient had a small extent of Imnecrosis, indicating high grade gliomas. The situation mentioned above can be avoided if a judgement of Imnecrosis is made, which is one unique advantage of radiographic ex- amination. Besides, we identified seven patients with Imnecrosis who were diagnosed as oligoden- drogliomas, IDH-mutant and 1p/19q-deleted, CNS WHO grade 2 or 3, indicating that necrosis plays a limited predictive value in oligodendrogliomas. Hence, if there is evidence of oligodendrogliomas, such as calcification and filiform or localized inter- nal homogeneous enhancement, Imnecrosis does not indicate a high-grade tumor. Besides, Waqar et al. reported this kind of reinforcement as a “chicken wire” appearance with the explanation that oligo- dendroglioma vasculature often was described as a network of regular fine branching capillaries.16,17 Previous studies have highlighted that Imnecrosis is an independent unfavorable prognosis fac- tor.5,6,10,18-20 Our results were in accordance with their findings. Besides, the latest WHO CNS classi- fication emphasizes the role of molecular markers, such as IDH, 1p19q, CDKN2A/B, 7+/10-, and EGFR, in the diagnosis and prediction of the prognosis of gliomas.4 From this prospect, Imnecrosis might be more critical than Panecrosis since it can be non-inva- sively obtained before operation. However, there was no significant difference between the expres- sions of 7+/10- cytogenetic signature or EGFR am- plification and the presence of Imnecrosis. This nega- tive result might be due to the small sample size and insufficient number of events. In this study, we also sought quantitative met- rics for indicating tumor necrosis. Our results revealed that, compared with tumor without Imnecrosis/Panecrosis, DCE-derived metrics in tumor TABLE 2. Detailed clinical, imaging and pathological information of Only Imnecrosis group and Only Panecrosis group Group Grade Sex Age OS (month) IDH (0:wild; 1:mutant) 1p19q (0:non- codeletion; 1:codeletion) CDKN2A/B (0:non- deletion; 1:deletion) EGFR amplification (0:non- amplification; 1:amplification) chr7 gain/10 loss(0:negative; 1:positive) Pathology Only Panecrosis group WHO CNS grade 4 female 63 2.5 1 0 0 NA NA Astrocytoma,IDH-mutant Only Panecrosis group CNS WHO grade 4 female 55 20 0 0 NA 0 NA Glioblastoma,IDH-wildtype Only Panecrosis group CNS WHO grade 2 female 36 NA 1 1 0 NA NA Oligodendroglioma, IDH-mutant and 1p/19q-deleted Only Panecrosis group NA female 34 NA 1 NA NA NA NA IDH-mutation, NOS Only Imnecrosis group CNS WHO grade 4 male 64 5 0 0 NA 1 NA Glioblastoma,IDH-wildtype Only Imnecrosis group CNS WHO grade 2 male 40 25 1 0 0 NA NA Astrocytoma,IDH-mutant Only Imnecrosis group CNS WHO grade 3 female 55 60.06 1 1 0 NA NA Oligodendroglioma, IDH-mutant and 1p/19q-deleted Only Imnecrosis group CNS WHO grade 2 male 26 5.39 1 0 0 0 0 Astrocytoma,IDH-mutant Only Imnecrosis group NQ male 40 7.19 0 0 NA 0 NA IDH-wildtype, NOS Only Imnecrosis group NA male 28 19.68 0 0 NA 0 0 IDH-wildtype, NOS Only Imnecrosis group CNS WHO grade 3 male 26 34.42 1 0 0 NA NA Astrocytoma,IDH-mutant CNS = central nervous system; NA = not available; NOS = not otherwise specified Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction30 parenchyma, except kep, were significantly higher in gliomas with Imnecrosis/Panecrosis. And ve in tumor parenchyma demonstrated the highest diagnos- tic efficiency in identifying tumor necrosis with high sensitivity and specificity. Significantly high DCE-MRI metrics may be attributed to gliomas growing uncontrollably fast, resulting in severe hypoxia and necrosis. Thus, an extensively hyper- permeable vasculature is generated, resulting in inadequate oxygen and supplements delivery. The FIGURE 4. Survival curves for cases of imaging necrosis (A), cases of pathological necrosis (B), and cases of both pathological and imaging necrosis (C). A B C TABLE 3. Representative results of non-parametric tests and ROC analyses between DCE-related data for gliomas with or without pathological necrosis/imaging necrosis Parameter p AUC (95% CI) Sensitivity Specificity Cut-off Panecrosis Tumor-ktrans-Mean < 0.001 0.824 (0.711 ~0.936) 0.94 0.625 0.07 Edema-ktrans-Mean 0.031* 0.655 (0.527 ~ 0.783) 0.833 0.46 0.03 Tumor-ve-Mean < 0.001 0.891 (0.788 ~ 0.995) 0.96 0.833 0.17 Edema-ve-Mean 0.002** 0.728 (0.613 ~ 0.842) 0.34 1 0.16 Tumor-kep-Mean < 0.001 0.872 (0.761 ~ 0.983) 0.833 0.86 2.48 Tumor-iauc-Mean < 0.001 0.899 (0.803 ~ 0.996) 1 0.75 0.07 Imnecrosis Tumor-ktrans-Mean < 0.001 0.856 (0.772 ~ 0.939) 0.877 0.757 0.08 Tumor-ve-Mean < 0.001 0.929 (0.872 ~ 0.986) 0.892 0.919 0.17 Edema-ve-Mean 0.005** 0.667 (0.558 ~ 0.776) 0.708 0.595 0.06 Tumor-kep-Mean < 0.001 0.914 (0.857 ~ 0.971) 0.946 0.831 2.74 Tumor-iauc-Mean < 0.001 0.909 (0.844 ~ 0.974) 0.8 0.946 0.13 * = p < 0.05; ** = p < 0.01 Radiol Oncol 2024; 58(1): 23-32. Ma H et al. / the importance of imaging necrosis in glioma diagnosis and prognostic prediction 31 greater the levels of perfusion and permeability in the tumor tissue, the higher the ktrans and ve and the higher the degree of tumor malignancy.21-23 Hence, DCE-MRI metrics, especially ve in tumor parenchyma (cut-off value: 0.17), might be a sup- plementary metric to the morphological observa- tion for delineating tumor necrosis. The current study has some limitations. First, since evidence of pathological necrosis was ob- tained from pathology reports of the same hos- pital, there may be an observation bias. However, this study, based on clinical real-world evidence, can exactly address the current clinical deficits. Second, this is a single-center study; subgroups analysis had a small sample, which might result in insufficient power to reach definite conclusions. Further multicenter studies with large sample siz- es will help improve the efficacy of Imnecrosis in pre- dicting the expression of molecular markers and prognosis. Conclusions Based on the latest WHO CNS guidelines, the present study depicted the importance of imag- ing necrosis in diagnosing gliomas. Detection of imaging necrosis in gliomas probably suggests an HGG unless there is imaging evidence for oligo- dendrogliomas, IDH-mutant and 1p/19q-deleted. Imaging necrosis was significantly associated with glioma-related key gene mutations, such as 1p19q non-codeletion and CDKN2A/B homozygous deletion. And it is an independent imaging marker for predicting tumor prognosis. Additionally, the Tumor-ve-Mean derived from DCE-MRI can help to predict necrosis with high sensitivity and speci- ficity. Overall, in this study, we re-evaluated the imaging necrosis in the assessment of gliomas and provided a feasible solution to solve the frequent diagnostic dilemma of gliomas. Acknowledgments This study was funded in part by the National Natural Science Foundation of China (grant num- bers 82172015, 82202217), the Natural Science Foundation of Guangdong Province (grant num- bers 2021A1515012279, 2022A1515011264), and the Science and Technology Program of Guangzhou, China (grant number 202201011244). References 1. Yee PP, Wei Y, Kim SY, Lu T, Chih SY, Lawson C, et al. Neutrophil-induced ferroptosis promotes tumor necrosis in glioblastoma progression. Nat Commun 2020; 11: 5424. doi: 10.1038/s41467-020-19193-y 2. Hou J, Zhao R, Xia W, Chang CW, You Y, Hsu JM, et al. PD-L1-mediated gasdermin C expression switches apoptosis to pyroptosis in cancer cells and facilitates tumour necrosis. Nat Cell Biol 2020; 22: 1264-75. doi: 10.1038/ s41556-020-0575-z 3. Jiao D, Cai Z, Choksi S, Ma D, Choe M, Kwon HJ, et al. Necroptosis of tumor cells leads to tumor necrosis and promotes tumor metastasis. Cell Res 2018; 28: 868-70. doi: 10.1038/s41422-018-0058-y 4. 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