Combining Inhomogeneous Magnetization Transfer and Myelin Water Imaging at 9.4T: Methodology and Limitations

Motivation: Myelin imaging techniques are often qualitative and lack specificity, hindering precise understanding of white matter and neurodegenerative diseases. Goal(s): This study aimed to enhance myelin imaging by combining Inhomogeneous Magnetization Transfer (ihMT) and Myelin Water Imaging (MWI) at 9.4T. Approach: Incorporating ihMT saturation pulses with the multi-echo spin-echo MWI readout acquisition facilitates myelin quantification through multi-contrast mechanisms. ihMT images protons with extended dipolar relaxation times, while MWI extracts myelin water contributions from T2 distributions. Results: Results revealed irregularities due to high-field-induced shortening of myelin water T2 values. Therefore, full T2 distributions could not be resolved, impeding further analyses such as myelin quantification. Impact: This study presents a myelin-specific imaging approach through the fusion of two quantitative techniques at 9.4T. Unresolved myelin water T2 peaks caused by the high field strength present a challenge, underscoring the need for further exploration at lower field strengths.