Adiabatic spin-lock preparations enable robust in vivo cardiac T_1ρ-mapping at 3T

Magnetic Resonance Imaging (MRI) is the clinical gold standard for the assessment of myocardial viability but requires injection of exogenous gadolinium-based contrast agents. Recently, T_1ρ-mapping has been proposed as a fully non-invasive alternative for imaging myocardial fibrosis without the need for contrast agent injection. However, its applicability at high fields is hindered by susceptibility to MRI system imperfections, such as inhomogeneities in the B₀ and B₁⁺ fields. In this work we propose a single breath-hold ECG-triggered single-shot bSSFP sequence to enable T_1ρ-mapping in vivo at 3T. Adiabatic T_1ρ preparations are evaluated to reduce B₀ and B₁⁺ sensitivity in comparison with conventional spin-lock (SL) modules. Numerical Bloch simulations were performed to identify optimal parameters for the adiabatic pulses. Experiments yield T_1ρ values in the myocardium equal to 48.13±54.08 ms for the best adiabatic preparation and 16.01±20.75 ms for the reference non-adiabatic SL, with 26.91% against 89.74% relative difference in T_1ρ values across two shimming conditions. Both phantom and in vivo measurements show increased myocardium/blood contrast and improved resilience against system imperfections compared to non-adiabatic T_1ρ preparations, enabling the use at 3T. Clinical relevance- Adiabatically-prepared T_1ρ-mapping sequences form a promising candidate for non-contrast evaluation of ischemic and non-ischemic cardiomyopathies at 3T.