Fig. 6

Evaluation of mid-wall global circumferential strain (GCS). Tagging images were collected at rest with breath-hold ECG-segmented and with repeated free-breathing real-time tagging sequences. Measurements of mid-wall GCS were obtained from tagging images in the short-axis view at basal, mid and apical levels and were averaged across slices. A The average strain obtained with the two different sequences was compared. Linear regression with forced zero intercept had a slope = 0.87 (0.83, 0.91), and Pearson correlation coefficient r was 0.71. Bland–Altman analysis showed a mean difference of − 2.3% (− 7.4, 2.8). B The average strain obtained from repeated real-time tagging sequence was compared to evaluate intra-subject repeatability of mid-wall GCS measures. Intraclass correlation coefficient was 0.86 (0.71, 0.94). The Bland–Altman analysis showed a mean difference of 0.2% (− 2.3, 2.8). In Bland–Altman plots, limits of agreement are shown as dotted black lines, and biases as solid red lines