The Real-World Cardiac T1 Mapping Spectrum: Diagnostic Ranges and Clinical Implications Across Various Conditions

Cardiac magnetic resonance (CMR) T1 mapping quantifies myocardial tissue changes, but its clinical integration is limited by the lack of comprehensive diagnostic ranges derived from large, heterogeneous patient populations. To establish the first quantitative diagnostic spectrum of native T1 and extracellular volume (ECV) across multiple cardiovascular conditions, and to evaluate the feasibility of using a contrast-free native T1 approach for optimizing clinical pathways. A total of 1,623 subjects encompassing 20 cardiovascular conditions were retrospectively enrolled from a real-world cohort. All participants underwent 3.0-T CMR with Modified Look-Locker Inversion recovery T1 mapping. Global native T1 and ECV were quantified, standardized against healthy controls via Cohen’s d, and analyzed through inter-group comparisons, receiver operating characteristic analysis, and multi-dimensional visualization. Native T1 and ECV ranges were defined across 20 cardiovascular conditions. Multi-dimensional T1 mapping spectra were constructed to facilitate clinical application. Cardiac amyloidosis showed the highest values (T1 1425±11 ms; ECV 53.2±1.1%), while iron-overload cardiomyopathy (709±31 ms) and Fabry disease (1115±11 ms) had markedly reduced native T1. However, substantial overlap was observed among fibrosis-predominant diseases. Both parameters demonstrated robust utility in discriminating disease from health, with native T1 showing comparable diagnostic performance to ECV in most cases. This study establishes a real-world diagnostic spectrum for T1 mapping, revealing distinctive signatures for certain diseases while highlighting substantial overlap among fibrosis-predominant conditions. A contrast-free, "native-first" clinical pathway may serve as an effective initial assessment strategy in selected clinical scenarios, with the potential to improve safety and efficiency. • First real-world T1 mapping spectrum across 20 cardiovascular conditions. • Native T1 shows comparable diagnostic performance to ECV for most diseases, supporting contrast-free pathways. • Multi-dimensional visualization reveals disease-specific patterns. • Substantial T1/ECV overlap among fibrosis-predominant diseases limits etiological specificity. • High reproducibility and real-world validation facilitate clinical integration of T1 mapping.