Comparison of cardiac MRI tissue tracking and myocardial tagging for assessment of regional ventricular strain

Abstract

This study sought to compare regional measures of ventricular strain by tissue tracking (TT) to those derived from myocardial tagging (MT) within cardiac MR (CMR), in normal subjects and patients with hypertrophic cardiomyopathy. CMR images from 13 normal subjects and 11 subjects with hypertrophic cardiomyopathy were retrospectively analyzed. For each subject, equivalent mid-papillary level short-axis cine steady-state free precession and MT slices from the same examination were evaluated. The time to peak circumferential strain and magnitude of the peak strain were calculated for 6 matched left ventricular segments. Data from 24 slices (n = 144 segments) were compared. The mean difference between techniques in magnitude of peak strain and time to peak strain was 1 ± 9% and 1 ± 58 ms, respectively. The mean difference in the standard deviation of time to peak strain within a slice was 0 ± 19 ms (mean cardiac cycle duration 1,013 ± 204 ms). Bland-Altman analysis showed closer agreement in time to peak strain than peak strain magnitude. Measurements of segmental time to peak strain by TT and MT were in close agreement; agreement for the magnitude of peak segmental strain was more modest. The TT approach does not add to CMR examination time and may be a useful tool for the assessment of ventricular synchrony.

Figure 1.

(A) Representative MT and cine SSFP short-axis images at the mid-papillary level from a normal subject. The myocardium was divided into 6 matching segments on the MT and SSFP images. (B) MT and TT analysis was performed to calculate the average endocardial circumferential strain within each segment at multiple time points throughout the cardiac cycle. MT = myocardial tagging, TT = tissue tracking.

Figure 2.

Bland-Altman plots of the magnitude of the peak endocardial circumferential strain for the TT and MT techniques: (A) whole slice; (B) segmental. The mean difference (bias) is shown as a solid line and the limits of agreement (± 2SD) as the dashed lines.

Figure 3.

Bland-Altman plots of the time to peak endocardial circumferential strain for the TT and MT techniques expressed as time in ms (A) and as a % of total cycle length (B).

Figure 4.

Bland-Altman plots of synchrony parameters for the TT and MT techniques. (A) Standard deviation of the time to peak endocardial circumferential strain for the 6 segments in the short axis; (B) time to peak endocardial circumferential strain, latest vs. earliest segment; and (C) time to peak endocardial circumferential strain, anteroseptal vs. inferolateral segment.