Noninvasive Assessment of O(6)‐Methylguanine‐DNA Methyltransferase Promoter Methylation Status in World Health Organization Grade II–IV Glioma Using Histogram Analysis of Inflow‐Based Vascular‐Space‐Occupancy Combined with Structural Magnetic Resonance Imaging

Abstract

Background: O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation is an important prognostic factor for gliomas and is associated with tumor angiogenesis. Arteriolar cerebral blood volume (CBVa) obtained from inflowbased vascular-space-occupancy (iVASO) magnetic resonance imaging (MRI) is assumed to be an indicator of tumor microvasculature. Its preoperative predictive ability for MGMT promoter methylation remains unclear. Purpose: To investigate the role of iVASO-CBVa histogram features in determining MGMT promoter methylation status of grade II-IV gliomas. Study Type: Retrospective Subjects: Forty-six patients consisting of 20 MGMT methylated and 26 unmethylated gliomas. Field Strength/Sequence: 3.0 T magnetic resonance images containing iVASO MRI, T 1 -weighted image (T 1 WI), T 2weighted image, T 2 -weighted fluid attenuated inversion recovery image images, and enhanced T 1 WI. Assessment: Sixteen structural imaging features were visually evaluated on structural MRI and 14 CBVa histogram features were extracted from iVASO-CBVa maps. Statistical Tests: Imaging features were screened and ranked using Fisher's exact test, Mann-Whitney U-test, and randomforest algorithm. Features with higher importance were selected to develop logistic regression models to determine MGMT methylation status. Receiver operating characteristics (ROC) curve with the area under the curve (AUC) and leave-one-out cross-validation (LOOCV) were used to assess effectiveness and stability.

Advanced Diagnosis of Glioma by Using Emerging Magnetic Resonance Sequences

“…CBVa obtained from iVASO MRI can identify the difference of tumor histogram and structural features between MGMT methylation gliomas and unmethylation ones. The root mean square and variance features from CBVa histogram and contrast-enhancing component of the tumor location from structural imaging enable the iVASO-CBVa to evaluate the MGMT methylation status in gliomas ( 39 ).…”

On the optimization of 3D inflow‐based vascular‐space‐occupancy (iVASO) MRI for the quantification of arterial cerebral blood volume (CBVa)

“…When flow-sensitive crushing gradients are incorporated to remove fast-flowing blood signals in large arteries, CBVa measured in iVASO MRI can be sensitized predominantly to microvasculature with arterial blood, here defined as small pial arteries and arterioles. Because CBVa is an important indicator of tissue perfusion and the integrity of microvasculature, iVASO MRI has been applied in a number of clinical studies, 7 including stroke 6 ; brain tumors [8][9][10][11][12][13][14] ; mental disorders such as schizophrenia 15,16 ; and neurodegenerative diseases such as Huntington's disease, Alzheimer's disease, and Parkinson's disease, [17][18][19][20] as well as in other tissue such as muscle. 21 In iVASO MRI, CBVa is calculated from the difference signal between an arterial blood nulled image and a second image without blood nulling (control).…”