Diffusion-Weighted SPECIAL Improves the Detection of J-Coupled Metabolites at Ultrahigh Magnetic Field

Motivation: Diffusion-weighted MR spectroscopy (dMRS) uniquely probes cell-specific tissue microstructure in vivo but most sequences suffer from long TE leading to signal loss by J-evolution and T2 relaxation. Goal(s): To propose an alternative dMRS sequence (DW-SPECIAL) with a shorter TE while preserving the benefits of the current gold-standard rodent sequence at high field (STE-LASER). Approach: DW-SPECIAL was tested in vivo in the rat brain and compared to STE-LASER. Results: DW-SPECIAL halved the minimum TE while reducing specific absorption rate compared to STE-LASER, thereby 1) improving the J-coupled metabolites’ diffusion properties estimation and 2) offering a new candidate sequence for human dMRS. Impact: With its shorter TE, our newly proposed DW-SPECIAL can serve as an alternative to STE-LASER when strongly J-coupled metabolites like glutamine are investigated, thereby extending the range of accessible metabolites in the context of diffusion-weighted MRS acquisitions at high field.