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

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 (ADC min ). An ROI was placed in the contralateral normal appearing white matter (NAWM) to obtain the ADC value (ADC NAWM ). The ADC min to ADC NAWM ratio (ADC ratio ) 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 ADC min and ADC ratio than IDH wild‐type glioma. Among IDH‐mutated glioma, higher ADC min and ADC ratio 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.