SNR ‐Efficient Inhomogeneous Magnetization Transfer ( ihMT ) for Clinical Applications at 7 T

ABSTRACT Purpose Inhomogeneous MT (ihMT) is an MRI modality sensitive to Myelin, the lipid‐rich membrane surrounding the axons. A novel ihMT saturation strategy and its associated correction at UHF are proposed. The aim is to generate a strong ihMT effect within a clinically compatible scan time while complying with SAR constraints at 7 T. Methods The MT preparation module of the proposed approach was shortened, reducing power deposition and allowing for shorter scan time while maximizing SNR efficiency. Optimization of the sequence was validated on (2 mm iso.) on a 7 T clinical scanner. Example high resolution images were acquired (1–1.4 mm iso.). Model‐based corrections were applied and their impact on ihMT quantification was studied. Numerical simulations and error quantifications were performed to complement experimental data. Results Fewer bursts () of cosine‐modulated MT preparation pulses () performed at maximal yielded strong ihMT signal with better SNR efficiency as compared to previously proposed long saturation trains (). correction showed a reliability range () which challenged applicability in strong hypo‐intense areas. High resolution acquisitions showed acceptable SNR () for resolutions down to 1 mm iso., enabling studies of fine structures (e.g., deep gray nuclei) with added specificity provided by ihMT. Conclusion ihMT applications at 7 T are enabled. While whole‐brain imaging requires further work to compensate for inhomogeneities, localized applications (e.g., Thalamus) are immediately feasible within clinically compatible scan time (< min). Similar sequence improvements are expected at lower field strengths (e.g., ).