Simulating MOLLI T1 mapping signals to remove variability caused by heart rate

Motivation: To remove the heart rate (HR) dependence of abdominal ShMOLLI T1 measures in the UK Biobank (UKBB) for improved accuracy of disease detection and organ age prediction. Goal(s): To generate a Look-Up Table (LUT) to HR-correct abdominal ShMOLLI T1 UKBB data. Approach: Bloch simulation of UKBB ShMOLLI schemes to create a LUT for HR-correction of abdominal T1 values. To study the influence of primary disease, and healthy kidney ageing on HR-corrected data. Results: Simulations show HR-correction is important for kidney medulla and corticomedullary difference (CMD) in T1. Kidney cortex T1 and CMD in T1 correlate with age. Impact: Errors arise in measured ShMOLLI T1 data when collected with ECG-triggering rather than with a fixed spacing. Removing the heart rate effect allows better comparison between health and disease groups, and to determine effects of ageing on kidney T1 measures.