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 (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.

Keywords: O6-methylguanine-DNA methyltransferase; diffusion magnetic resonance imaging; glioma; isocitrate dehydrogenase; molecular typing.