Assessment of left atrial native T1 values using non-contrast 3.0 T cardiac magnetic resonance imaging: a feasibility and reproducibility study

Abstract

Atrial cardiomyopathy (ATC) is characterized by structural and functional atrial remodeling and is associated with adverse cardiovascular outcomes. Native T1 mapping has emerged as a sensitive technique for tissue characterization; however, data on left atrial (LA) native T1 mapping remain limited. We evaluated the feasibility and reproducibility of LA T1 measurements using non-contrast 3.0-T cardiac magnetic resonance (CMR), thereby providing a methodological foundation for future studies of atrial tissue characterization. Healthy volunteers in sinus rhythm underwent non-contrast 3.0-T CMR, including native T1 mapping using a modified Look-Locker inversion recovery (5s(3s)3s MOLLI) sequence. LA native T1 values were measured in the 2-, 3-, and 4-chamber long-axis views. Two independent specialists measured LA native T1 values using regions of interest placed within the inner 2 reconstructed pixels of the LA wall to minimize in-plane partial volume effects. Feasibility was assessed by the proportion of measurable studies, and reproducibility by intra- and inter-observer intraclass correlation coefficients (ICC). Additional analyses were performed to assess potential blood-pool contamination. Forty volunteers (50% female; mean age 33.6 ± 6.1 years; body mass index of 22.7 ± 3.2 kg/m²) were included. LA native T1 values were measurable in 62.5%, 95.0%, and 75.0% of subjects in the 2-, 3-, and 4-chamber views, respectively, identifying the 3-chamber view as the most feasible imaging plane. Mean LA native T1 values were consistent across views (1,441–1,448 ms; all p > 0.05) without gender difference. Reproducibility was excellent, with intra-observer ICCs of 0.921–0.940 and inter-observer ICCs of 0.894–0.920. Agreement between views was good (ICC 0.709–0.878) without significant proportional bias. Blood-pool T1 values were substantially higher than LA T1 values (1,859–1,868 ms vs. 1,441–1,448 ms) and showed no significant correlation. Validation analyses demonstrated a progressive increase in blood-pool T1 values with increasing distance from the LA wall, supporting measurement specificity. Non-contrast T1 mapping enables feasible and highly reproducible quantification of LA native T1 values. The 3-chamber view demonstrated the highest measurability and may be the preferred imaging plane for LA tissue characterization. These findings provide a methodological framework for future investigations of ATC and other atrial diseases. Not applicable.