Quantification of myocardial strain assessed by cardiovascular magnetic resonance feature tracking in healthy subjects-influence of segmentation and analysis software

Abstract

Objectives: Quantification of myocardial deformation by feature tracking is of growing interest in cardiovascular magnetic resonance. It allows the assessment of regional myocardial function based on cine images. However, image acquisition, post-processing, and interpretation are not standardized. We aimed to assess the influence of segmentation procedure such as slice selection and different types of analysis software on values and quantification of myocardial strain in healthy adults.

Methods: Healthy volunteers were retrospectively analyzed. Post-processing was performed using CVI⁴² and TomTec. Longitudinal and radial_{Long axis (LAX)} strain were quantified using 4-chamber-view, 3-chamber-view, and 2-chamber-view. Circumferential and radial_{Short axis (SAX)} strain were assessed in basal, midventricular, and apical short-axis views and using full coverage. Global and segmental strain values were compared to each other regarding their post-processing approach and analysis software package.

Results: We screened healthy volunteers studied at 1.5 or 3.0 T and included 67 (age 44.3 ± 16.3 years, 31 females). Circumferential and radial_SAX strain values were different between a full coverage approach vs. three short slices (- 17.6 ± 1.8% vs. - 19.2 ± 2.3% and 29.1 ± 4.8% vs. 34.6 ± 7.1%). Different analysis software calculated significantly different strain values. Within the same vendor, different field strengths (- 17.0 ± 2.1% at 1.5 T vs. - 17.0 ± 1.7% at 3 T, p = 0.845) did not influence the calculated global longitudinal strain (GLS), and were similar in gender (- 17.4 ± 2.0% in females vs. - 16.6 ± 1.8% in males, p = 0.098). Circumferential and radial strain were different in females and males (circumferential strain - 18.2 ± 1.7% vs. - 17.1 ± 1.8%, p = 0.029 and radial strain 30.7 ± 4.7% vs. 27.8 ± 4.6%, p = 0.047).

Conclusions: Myocardial deformation assessed by feature tracking depends on segmentation procedure and type of analysis software. Circumferential_SAX and radial_SAX depend on the number of slices used for feature tracking analysis. As known from other imaging modalities, GLS seems to be the most stable parameter. During follow-up studies, standardized conditions should be warranted. Trial registration Retrospectively registered KEY POINTS: • Myocardial deformation assessed by feature tracking depends on the segmentation procedure. • Global myocardial strain values differ significantly among vendors. • Standardization in post-processing using CMR feature tracking is essential.

Keywords: Healthy volunteers; Left ventricular function; Magnetic resonance imaging; Myocard; Software.

Fig. 1

Post-processing using 2D strain analysis by CVI⁴². Endo- (red) and epicardial (green) contours were manually drawn in end-diastolic phase in long axis (a–c) and short axis (d–f). 4-chamber-view (a), 3-chamber-view (b), and 2-chamber-view (c) were included in long-axis strain analysis. For short-axis strain, contours were drawn in three short-axis slices: basal (d), midventricular (e), and apical (f)

Fig. 2

Strain analysis using full coverage (CVI⁴²). Endo- and epicardial contours were drawn in end-diastolic phase (a). If LVOT was visible in end-systolic phase (b, marked red), slices were excluded. The first slice used for analysis was chosen as the most basal slice that did not show LVOT in any end-diastolic (a, marked green) and end-systolic phase (b, marked green)

Fig. 3

Quality assessment for accurate tracking and correct segmentation applying CVI⁴². a Optimal segmentation. b and c show incorrect segmentations in 3-chamber-view: the basal inferolateral segments are relatively short (*) and the apical septal segment extends to apical lateral (°). Additionally, contours do not follow endocardial borders accurately (∆)

Fig. 4

2D strain analysis of the left ventricle using different post-processing software. Strain was analyzed using CVI⁴² (a–b) and TomTec software (c–d). Longitudinal and radial_LAX strain were assessed in 4CV, 3CV (a, c), and 2CV; circumferential and radial_SAX strain were analyzed in basal (b, d), medial, and apical short-axis slice

Fig. 5

Gender-related mean values for longitudinal strain using CVI⁴². Segmental values are provided as mean (in %) ± standard deviation in a bulls-eye plot according to the AHA segment model [31]. Segment 5 (marked red) differed between genders (p = 0.048)