A pulse sequence for single breath hold 3d fetal magnetization transfer

Motivation: Magnetization transfer (MT) fetal imaging could facilitate understanding of fetal tissue microstructure and metabolism throughout pregnancy, and enable early detection and reveal aetiology of developmental abnormalities. Metabolic MRI acquisitions are, however, long and susceptible to motion artifacts, which are unpredictable when imaging the fetus. Goal(s): Develop an MT pulse sequence optimized for gestational imaging, with acquisition time reduced to within a maternal breath hold. Approach: A yarnball ultrashort echo time acquisition with multiband alternating phase saturation, and reduced Z-spectrum sampling. Results: The pulse sequence captures an MT-weighted signal within a tolerable breath hold that is sensitive to physiological MT and robust to confounds. Impact: This work is a stepping stone toward clinical in utero metabolic and microstructural imaging. The development of this sequence demonstrates a framework that can be applied to other saturation transfer analytes, making endogenous metabolic and microstructural imaging more broadly applicable.