Myocardial T1 Mapping Protocol

Myocardial T1 mapping was performed using the modified look-locker inversion-recovery (MOLLI) sequence [flip angle: 35°, minimum time to inversion (TI): 100 ms, TI increment: 80 ms, time delay: 150 ms, heart beat acquisition scheme: 5-(3)-3].^{19 (link)} Regions of interest (ROI) were drawn within the mid-septum on short-axis, motion-corrected native T1 maps and copied onto corresponding 15-min post-contrast maps, with minor adjustments to minimize partial volume artefact, as previously described.^{20 (link)} T1 analysis was performed with Argus software (Siemens, Erlangen, Germany), as previously described.^{21 (link)} The T1 values were the mean of all pixels within the ROI. Analysis was performed by an experienced CMR reader, blinded to all other data. The ECV was calculated as^{20 (link)}: ECV = (ΔR1_myocardium/ΔR1_blood-pool) × (1 − haematocrit), where ΔR1 = (1/post-contrast T1 − 1/native T1). Myocardial cell volume fraction was defined, as previously,^{22 (link)} as 1 − ECV and multiplied by indexed myocardial volume (indexed LVM divided by 1.05 g/mL, the myocardial specific gravity). Indexed interstitial volume was defined as ECV × indexed myocardial volume. This T1 technique analysis has previously been demonstrated to yield high reproducibility.^{21 (link),23}