Robust cardiac T 1 ρ $$ {\mathrm{T}}_{1_{\boldsymbol{\rho}}} $$ mapping at 3T using adiabatic spin-lock preparations

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Quantitative MRI
• Biophysical Modeling

Background:

• Accurate quantification of myocardial T1 relaxation times is crucial for diagnosing and monitoring cardiovascular diseases.
• Conventional spin-lock (SL) preparations are susceptible to magnetic field inhomogeneities, limiting their robustness in vivo.
• Adiabatic pulse techniques offer potential for improved resilience against such inhomogeneities.

Purpose of the Study:

• To develop and optimize an adiabatic spin-lock (aSL) mapping method for robust myocardial T1 quantification at 3 Tesla (3T).
• To evaluate the performance of optimized aSL preparations compared to conventional SL methods.
• To assess the clinical utility of aSL in patients with cardiovascular disease.

Main Methods:

• Adiabatic SL (aSL) preparations were optimized using Bloch simulations for resilience against B1 and B0 inhomogeneities.
• Myocardial T1 mapping was performed using a cardiac-triggered bSSFP-based sequence with optimized aSL modules.
• Comparisons were made against conventional SL-prepared (RefSL) maps in phantoms and 13 healthy subjects, and in six patients with cardiovascular disease.

Main Results:

• Simulations identified optimal aSL modules comprising 2 HS pulses (30 ms each) for highest preparation efficiency.
• In vivo aSL T1 maps demonstrated significantly higher quality, precision (14.47% vs 37.61%), and reproducibility (4.64% vs 47.39%) compared to RefSL.
• aSL methods showed reduced inter-subject variability (8.76% vs 51.90%) and improved artifact resilience in patients, with T1 alterations correlating with LGE findings.

Conclusions:

• Adiabatic preparations provide a robust method for in vivo quantification of myocardial spin-lock relaxation times at 3T.
• The developed aSL mapping technique significantly enhances precision and reproducibility, outperforming conventional SL methods.
• aSL mapping holds promise for improved cardiovascular magnetic resonance imaging applications.