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BackgroundNative T1 may be a sensitive, contrast-free, non-invasive cardiovascular magnetic resonance (CMR) marker of myocardial tissue changes in patients with pulmonary artery hypertension. However, the diagnostic and prognostic value of native T1 mapping in this patient group has not been fully explored. The aim of this work was to determine whether elevation of native T1 in myocardial tissue in pulmonary hypertension: (a) varies according to pulmonary hypertension subtype; (b) has prognostic value and (c) is associated with ventricular function and interaction.MethodsData were retrospectively collected from a total of 490 consecutive patients during their clinical 1.5 T CMR assessment at a pulmonary hypertension referral centre in 2015. Three hundred sixty-nine patients had pulmonary hypertension [58 ± 15 years; 66% female], an additional 39 had pulmonary hypertension due to left heart disease [68 ± 13 years; 60% female], 82 patients did not have pulmonary hypertension [55 ± 18; 68% female]. Twenty five healthy subjects were also recruited [58 ±4 years); 51% female]. T1 mapping was performed with a MOdified Look-Locker Inversion Recovery (MOLLI) sequence. T1 prognostic value in patients with pulmonary arterial hypertension was assessed using multivariate Cox proportional hazards regression analysis.ResultsPatients with pulmonary artery hypertension had elevated T1 in the right ventricular (RV) insertion point (pulmonary hypertension patients: T1 = 1060 ± 90 ms; No pulmonary hypertension patients: T1 = 1020 ± 80 ms p < 0.001; healthy subjects T1 = 940 ± 50 ms p < 0.001) with no significant difference between the major pulmonary hypertension subtypes. The RV insertion point was the most successful T1 region for discriminating patients with pulmonary hypertension from healthy subjects (area under the curve = 0.863) however it could not accurately discriminate between patients with and without pulmonary hypertension (area under the curve = 0.654). T1 metrics did not contribute to prediction of overall mortality (septal: p = 0.552; RV insertion point: p = 0.688; left ventricular free wall: p = 0.258). Systolic interventricular septal angle was a significant predictor of T1 in patients with pulmonary hypertension (p < 0.001).ConclusionsElevated myocardial native T1 was found to a similar extent in pulmonary hypertension patient subgroups and is independently associated with increased interventricular septal angle. Native T1 mapping may not be of additive value in the diagnostic or prognostic evaluation of patients with pulmonary artery hypertension.Electronic supplementary materialThe online version of this article (10.1186/s12968-018-0501-8) contains supplementary material, which is available to authorized users.

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Although late gadolinium enhancement on cardiac magnetic resonance imaging remains the reference standard for scar assessment, it does not provide quantitative information about the extent of pathophysiological changes within the scar tissue. T1 mapping and extracellular volume (ECV) mapping are steadily becoming diagnostic and prognostically useful tests for in vivo myocardial histology, influencing clinical decision-making. Quantitative native T1 maps (acquired without a contrast agent) represent the longitudinal relaxation time within the myocardium and changes with myocardial extracellular water (edema, focal, or diffuse fibrosis), fat, iron, and amyloid protein content. Post-contrast ECV maps estimate the size of the extracellular space and have sensitivity in the identification of interstitial disease. Both pre- and post-contrast T1 mapping are emerging as comprehensive tools for the assessment of numerous conditions including ischemic scarring that occurs post myocardial infarction (MI). This review outlines the current evidence and potential future role of T1 mapping in MI. We conclude by highlighting some of the remaining challenges such as quality control, standardization of image acquisition for clinical practice, and automated methods for quantifying infarct size, area at risk, and myocardial salvage post MI.