Comparison of ectopic versus normal gray matter via quantitative magnetic resonance imaging: a cross-sectional study

Gray matter heterotopia (GMH) involves the abnormal migration of cortical neurons into the white matter and is often associated with epileptic seizures. Although conventional magnetic resonance imaging only provides the anatomical details of GMH, this study investigated the potential differences between GMH and normal gray matter (NGM) using arterial spin labeling (ASL) and magnetic resonance image compilation (MAGiC) quantitative techniques.

Retrospective data collection was conducted on 32 cases of GMH at the Second Affiliated Hospital of Nanchang University between October 2022 and October 2023. Patients underwent T1 brain volume (BRAVO), T2 weight imaging, ASL, and MAGiC sequences. Cerebral blood flow (CBF) values with postlabeling delays of 1.5 s and 2.5 s in ASL, along with T1, T2, and proton density values in MAGiC sequences, were measured and normalized against those of normal white matter. Paired-sample t-tests were applied to compare quantitative values between NGM and GMH before and after normalization.

The average CBF values of GMH with dual postlabeling delays (31.96 mL/100 g/min and 35.13 mL/100 g/min) were both significantly lower than those of NGM (52.69 mL/100 g/min and 56.93 mL/100 g/min) (P<0.001). After normalization with contralateral white matter CBF values, the difference remained significant (P<0.001). The differences in CBF values between GMH and NGM were not associated with the postlabeling delay (P=0.500). However, there were differences in T1 values between NGM and GMH before and after the normalization of MAGiC sequences (P<0.001), but no significant differences were observed in the T2 or proton density values before and after normalization (P>0.05).

NGM and GMH demonstrate quantitative differences in the ASL and MAGiC sequences.