Reference Values of Myocardial T1 Relaxation Times in Healthy Latin American Patients

Abstract

Theoretical framework. Cardiac magnetic resonance imaging (CMR) is an invaluable tool for diagnosis and risk stratification in a broad spectrum of cardiac diseases. Magnetic resonance imaging techniques are increasingly complemented by mapping sequences that allow quantitative assessment of myocardial tissue with measurement of absolute relaxation times T1, T2, and T2*. The clinical utilities are diverse, among which is the quantification of edema and/or fibrosis through the estimation of the extracellular volume fraction calculated from pre-contrast, post-contrast and hematocrit T1 relaxation times. There are multiple ways to obtain T1 mapping images, among which the modified look-locker inversion recovery technique (MOLLI) stands out. However, different manufacturers have designed various methods of obtaining them with slight variability between the equipment. Aim To determine the reference values of myocardial T1 relaxation times in our population to justify their clinical interpretation in the tissue evaluation of different cardiovascular diseases. Material and method. Type of study: prospective observational and single center. Field intensity/sequence A short CMR protocol was performed in a 1.5 T resonator, using the MOLLI technique, in T1 mapping. Evaluation Global and segmental T1 values were quantified, using the American Heart Association (AHA) model, for the entire left ventricle, in three short-axis slices (basal, mid, and apical). The post processing and analysis of the data with the commercialized software, Cvi42. Results The mean global myocardial T1 value was 1069.41 ms with a SD of 38.73 msec. Among the age groups, the <34-year-old group had the lowest global T1 values (1057 SD 33 msec), and the 35-year-old group -44 years obtained the highest values (1100 SD 50 msec), so no relationship was found between the linear increase in age and the variability of relaxation times. Between both sexes, men had lower global T1 values than women (1049 vs 1086). conclusions Native T1 ranges can serve as a basis for the quantitative characterization of the myocardium in the context of focal or diffuse diseases, in patients with infarcts, storage diseases, and inflammatory diseases. We are getting closer to standardizing the clinical use of these techniques by CMR. In conclusion, this analysis allows us to take another step to establish their use in the Latin American population.