Fast myocardial T₁ mapping using shortened inversion recovery based schemes.

Area of Science:

• Cardiovascular MRI
• Quantitative Imaging
• Biomedical Engineering

Background:

• Myocardial T1 mapping is crucial for assessing cardiomyopathies.
• Conventional techniques like modified Look-Locker inversion recovery (MOLLI) require prolonged breath-holds (9-17 heartbeats).
• This limits applicability for patients with breath-holding difficulties and extends scan times.

Purpose of the Study:

• To develop and characterize novel T1 mapping schemes using shortened inversion recovery.
• These new schemes aim for acquisition times of 2-5 heartbeats.

Main Methods:

• Numerical simulations, phantom studies, and imaging of 16 healthy volunteers and 24 patients at 1.5T.
• Comparison of novel shortened T1 mapping schemes against the conventional MOLLI (5-(3)-3) sequence.
• Assessment of accuracy, precision, spatial variability, and repeatability.

Main Results:

• Shortened schemes showed limited T1 time variations (≤2%) and precision penalties (~1.4-1.5x) compared to MOLLI in simulations.
• No significant differences in accuracy, spatial variability, or repeatability were found in phantom studies (P > 0.71).
• Healthy volunteers exhibited no significant differences in native T1 times or repeatability for myocardium and blood across schemes (P > 0.21).
• A slight increase in spatial variability (1.2x) was observed for shortened schemes (P < 0.0001).
• The two-heartbeat scheme and MOLLI demonstrated highly linear correlation (≥0.83) in T1 times.

Conclusions:

• The proposed two-heartbeat T1 mapping scheme achieves a 5-fold acceleration compared to MOLLI.
• It maintains highly correlated T1 times, similar repeatability, and minimal spatial variability penalty.
• This accelerated method facilitates myocardial T1 mapping in patients with breath-holding challenges and reduces overall scan duration.