Aims: To determine the bioequivalence of several T1 mapping sequences in myocardial characterization of diffuse myocardial fibrosis.
Methods and results: We performed an intra-individual sequence comparison of three types of T1 mapping sequences [MOdified Look-Locker Inversion recovery (MOLLI), Shortened MOdified Look-Locker Inversion recovery ((sh)MOLLI), and SAturation recovery single-SHot Acquisition (SASHA)]. We employed two model diseases of diffuse interstitial fibrosis [patients with non-ischaemic dilated cardiomyopathy (NIDCM), n = 32] and aortic stenosis [(AS), n = 25)]. Twenty-six healthy individuals served as controls. Relationship with collagen volume fraction (CVF) was assessed using endomyocardial biopsies (EMB) intraoperatively in 12 AS patients. T2 mapping (GraSE) was also performed. Myocardial native T1 with MOLLI and shMOLLI showed, firstly, an excellent discriminatory accuracy between health and disease [area under the curves (P-value): 0.94 (0.88-0.99); 0.87 (0.79-0.94); 0.61 (0.49-0.72)], secondly, relationship between histological CVF [native T1 MOLLI vs. shMOLLI vs. SASHA: r = 0.582 (P = 0.027), r = 0.524 (P = 0.046), r = 0.443 (P = 0.150)], and thirdly, with native T2 [r = 0.628(P < 0.001), r = 0.459 (P = 0.003), r = 0.211 (P = 0.083)]. The respective relationships for extracellular volume fraction with CVF [r = 0.489 (P = 0.044), r = 0.417 (0.071), r = 0.353 (P = 0.287)] were significant for MOLLI, but not other sequences. In AS patients, native T2 was significantly higher compared to controls, and associated with levels of C-reactive protein and troponin.
Conclusion: T1 mapping sequences differ in their bioequivalence for discrimination between health and disease as well as associations with diffuse myocardial fibrosis.