RAFF2 (Relaxation Along Fictitious Field of rank 2) normal values for 1.5 T Cardiac MRI
S Iso-Mustajarvi, M Husso, M Liukkonen, M Hedman, M Ugander, M Nissi, T Liimatainen, M Nieminen, R Sund, S Sillanmaki, E Yla-HerttualaAbstract
Background
Myocardial fibrosis is a common pathological feature of many cardiovascular diseases and is associated with adverse outcomes. Cardiac magnetic resonance imaging (cMRI) enables non-invasive myocardial tissue characterization, but conventional fibrosis imaging methods require contrast agents and have limited sensitivity for diffuse disease.
Purpose
Relaxation Along a Fictitious Field of rank 2 (RAFF2) is a novel contrast-free rotating-frame MRI technique; however, normal reference values in humans are currently lacking.
Methods
We prospectively recruited healthy volunteers with no history of cardiovascular disease or use of cardiovascular medication. After comprehensive clinical screening, including electrocardiography, echocardiography, and laboratory testing, 40 subjects underwent 1.5 T cMRI. Due to data quality criteria, RAFF2 analysis was successfully performed in 34 individuals (17 men, 17 women). RAFF2 relaxation times were measured in a mid-ventricular short-axis slice and analyzed globally and segmentally. Participants were stratified by age and sex. Statistical analyses assessed differences between groups and correlations between RAFF2 and conventional relaxation parameters.
Results
The mean global RAFF2 relaxation time for the overall cohort was 145 ± 13 ms. Mean values were 141 ± 12 ms in men and 148 ± 13 ms in women, with no significant sex-related differences. RAFF2 values did not differ significantly across age groups. Segmental RAFF2 values were consistent across myocardial regions. Mild correlations were observed between global RAFF2 and native T1, T2, and septal T2* relaxation times.
Conclusion
This study establishes age- and sex-specific normal reference values for RAFF2 relaxation time at 1.5 T in a heart-healthy adult population. These reference values provide a necessary foundation for future clinical studies investigating RAFF2 in cardiovascular disease and myocardial fibrosis.Fig 1Fig 2