Apparent Diffusion Coefficient as Imaging Biomarker for Identifying IDH Mutation, 1p19q Codeletion, and MGMT Promoter Methylation Status in Patients With Glioma

Abstract

Background Glioma genotypes are of importance for clinical decision‐making. This data can only be acquired through histopathological analysis based on resection or biopsy. Consequently, there is a need for alternative biomarkers that noninvasively provide reliable information for preoperatively identifying molecular characteristics. Purpose To investigate apparent diffusion coefficient (ADC) as imaging biomarker for preoperatively identifying glioma genotypes based on the 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors. Study Type Retrospective. Subjects One hundred and fifty‐nine patients (47.6 ± 14.4 years) diagnosed with WHO grade 2–4 glioma including 93 males and 66 females. Field Strength/Sequence A 3 T/spin echo echo planner imaging. Assessment The ADC measurements were assessed by two neuroradiologists (both with 6 years of experience). Three different lowest portions inside the tumors without overlap were manually drawn on the ADC maps as regions of interest (ROIs). The mean ADC value of the three ROIs was defined as the minimum ADC value (ADCmin). An ROI was placed in the contralateral normal appearing white matter (NAWM) to obtain the ADC value (ADCNAWM). The ADCmin to ADCNAWM ratio (ADCratio) was calculated. Genetics results were retrospectively recorded from pathologic and genetic test reports. Statistical Tests Two‐sample independent t‐tests, receiver operating characteristic curve analysis, and intraclass correlation coefficient analysis were used. Statistical significance was set at P < 0.05. Results Isocitrate dehydrogenase (IDH)‐mutated glioma showed higher ADCmin and ADCratio than IDH wild‐type glioma. Among IDH‐mutated glioma, higher ADCmin and ADCratio were found in 1p19q intact glioma than in 1p19q codeletion glioma. ADC parameters enabled differentiation of IDH mutation status with area under the curve (AUC) of 0.84 and 0.86. Data Conclusion ADC has potential discriminative value for IDH mutation and 1p19q codeletion status. Evidence Level 3. Technical Efficacy Stage 2.

Advancing noninvasive glioma classification with diffusion radiomics: Exploring the impact of signal intensity normalization

“…It highlights the relationship between cellular density and water diffusion in gliomas, with aggressive tumors showing lower ADC values due to high cellular density restricting water diffusion, and less aggressive tumors exhibiting higher ADC values. 27 Our study confirms that ADC radiomics significantly improves IDH-wt and IDH-mut non-codel glioma prediction, a finding consistent with previous research indicating that IDH-mut gliomas show higher ADC values compared to IDH wt 28 and texture features of ADC are useful for determining the 1p/19q status. 28–30 …”

“… 27 Our study confirms that ADC radiomics significantly improves IDH-wt and IDH-mut non-codel glioma prediction, a finding consistent with previous research indicating that IDH-mut gliomas show higher ADC values compared to IDH wt 28 and texture features of ADC are useful for determining the 1p/19q status. 28–30 …”

Imaging the WHO 2021 Brain Tumor Classification: Fully Automated Analysis of Imaging Features of Newly Diagnosed Gliomas

“…Among IDH mutant gliomas, 1p/19q intact gliomas seem to exhibit higher ADC values than 1p/19q codeleted gliomas. In contrast to our study, this analysis was not based on a fully automated extraction of imaging metrics from all tumor volumes but on individually placed regions of interest, which poses a possible source of error [ 25 ].…”

Editorial for “Apparent Diffusion Coefficient as Imaging Biomarker for Identifying IDH Mutation, 1p19q Codeletion, and MGMT Promoter Methylation Status in Patients With Glioma”

“…Ma et al investigated apparent diffusion coefficient ratio (ADC ratio ) value as a preoperative diagnostic imaging biomarker in gliomas and concluded that ADC ratio values enable the identification of 1p/19q co‐deletion and IDH mutation status in IDH mutated glioma. In the design of the present study by Ma et al, there are IDH mutant/1p19q mutant, IDH mutant/1p19q intact, and IDH wild‐type groups, and also in high‐grade glioma, O(6)‐methylguanine‐DNA methyltransferase (MGMT) methylated and non‐methylated groups 8 . MGMT methylation was not examined in the low‐grade gliomas, which is not unreasonable as the clinical impact of MGMT status on benefit from temozolomide or other alkylating agents has not been determined.…”

“…In the design of the present study by Ma et al, there are IDH mutant/1p19q mutant, IDH mutant/1p19q intact, and IDH wild-type groups, and also in high-grade glioma, O(6)-methylguanine-DNA methyltransferase (MGMT) methylated and non-methylated groups. 8 MGMT methylation was not examined in the lowgrade gliomas, which is not unreasonable as the clinical impact of MGMT status on benefit from temozolomide or other alkylating agents has not been determined. Furthermore, MGMT methylation in low-grade gliomas is often significantly associated with IDH mutation and/or 1p/19q co-deletion and these are well-established prognostic factors for survival.…”