T2∗ magnetic resonance imaging: A non-invasive biomarker of brain iron content in children with attention-deficit/hyperactivity disorder

Purpose: The aims of this study were the followings: First: To compare brain iron content in children with Attention-Deficit/Hyperactivity Disorder (ADHD) and healthy control subjects, estimated by T2∗ MRI value and its reciprocal R2∗. Second: To assess the association between brain iron content and distinct types of ADHD (predominantly inattentive, predominantly hyperactive/impulsive, or combined). Third: To test the ability of T2∗ MRI to grade the severity of ADHD. Patients and methods: 35 children (17 ADHD patients and 18 healthy non-ADHD controls) underwent T2∗-MRI to assess brain iron content. R2∗ value is calculated for both thalami. Results: ADHD group showed significantly lower R2∗ (mean 14.9 s−1 ± 1.3) value when compared to control group (mean R2∗ 16.6 s−1 ± 0.9) (p =< 0.001). Best cutoff value for R2∗ was 15.65 s−1, and R2∗ less than 15.65 s−1 showed good AUC for prediction of ADHD. Combined ADHD type showed significantly lower R2∗ when compared to inattentive type (p = 0.033 respectively). No significant correlations were found between R2∗ value and severity of ADHD. Conclusion: T2∗ MRI represents a reliable non-invasive tool for probing brain iron contents. Lower R2∗ values correlate with ADHD type but not with ADHD severity