Value of three‐dimensional speckle‐tracking imaging in detecting left ventricular systolic function in patients with dilated cardiomyopathy

Abstract Objective To explore the value of three‐dimensional speckle‐tracking imaging (3DSTI) in detecting left ventricular systolic function in patients with dilated cardiomyopathy (DCM). Methods Totally 31 DCM patients were enrolled in this study. Left ventricular end‐systolic volume (LVESV), left ventricular end‐diastolic volume (LVEDV), and left ventricular ejection fraction (LVEF) were measured using the 3DSTI, two‐dimensional echocardiography (2DE), and magnetic resonance imaging (MRI). Left ventricular end‐diastolic mass (EDmass) and left ventricular end‐diastolic mass index (LVEDmass I) were also detected by 3DSTI and MRI. The differences in these measurements were analyzed and compared. Results The values of LVESV, LVEDV, and LVEF showed significantly positive correlations among 2DE group, 3DSTI group, and MRI group. The LVEF value showed significant difference among these three groups [(33.3 ± 11.1)%, (30.3 ± 10.6)%, and (26.2 ± 10.7)%; P = 0.04], whereas LVEDV and LVESV values were not significantly different (P > 0.05; respectively). Inter‐group comparison showed the mean of LVEF was significantly lower in MRI group than in 2DE group (P = 0.031), whereas there was no significant difference between 2DE group and 3DSTI group and between 3DSTI group and MRI group (P > 0.05; respectively). The EDmass and EDmassI detected by 3DSTI and MRI were (143.2 ± 40.2) g vs (190.0 ± 58.3) g and (83.2 ± 21.1) g/m2 vs (110.1 ± 29.7) g/m2 (P < 0.001; respectively). Conclusions The LVEF value detected by 3DSTI is closer to that detected by MRI in DCM patients.


| Methods
Cardiac images were collected and stored by 2DE and 3DSTI, respectively. The images were acquired by the same cardiac sonographer and then the 2DE and 3DSTI images were analyzed independently by two other cardiac sonographers respectively.
Each image was analyzed twice by the same cardiac sonographer at different times, and the average value of the two values is used for statistical analysis.

| 2DE
Left ventricular end-systolic volume (LVESV), left ventricular end-diastolic volume (LVEDV), and LVEF were measured using the biplane Simpson's method in the apical two-and four-chamber views.

| 3DSTI
The M3S probe was placed at the apex and near the sternum to collect the 2D ultrasound images in four-chamber, two-chamber, left ventricular long-axis, mitral valve level, papillary muscle level, and apical left ventricular short-axis views. The V3 probe was placed at the apex to collect images in the apical four-chamber, two-chamber, and left ventricular long-axis views, followed by collection of four consecutive cycles of cone images when patients were holding their breath to form the left ventricular full volumetric 3D images. The images were processed and stored by using the GE EchoPac software.
The full volumetric images during the systolic and diastolic periods in the four-chamber, two-chamber, and left ventricular long-axis views were collected to determine the endpoints of the connection line between apex and mitral annulus. The software automatically generated the left ventricular endocardial and the epicardial boundaries, which could be manually adjusted. Subsequently, the software automatically generated LVESV, LVEDV, LVEF, and left ventricular end-diastolic mass (EDmass). Then, the left ventricular end-diastolic mass index (LV EDmass I) was calculated based on the body height and body weight.

| MRI
The images at transverse, coronal, and sagittal positions and in the standard two-and four-chamber views were collected; with these images as scout images, the cine images in short-axis, two-chamber, and four-chamber views were acquired. A fast gradient echo pulse sequence was used to scan from the base of the heart to the apex sequentially, and the results were Then, the LV EDmass I was calculated based on the body height and body weight.

| Statistical analysis
Data were expressed as mean ± standard deviations (x ± s). One-way ANOVA was used to analyze the data differences among these three groups, and Student-Newman-Keuls test was used to compare the data between two groups. The comparisons between two groups were based on t test. Correlation analysis was based using Pearson correlation analysis; P < 0.05 was considered significantly different.

| Comparisons of left ventricular function parameters
The values of LVESV, LVEDV, and LVEF detected by the three methods were positively correlated with each other (P < 0.001, respectively; Figure 1). The mean of LVEF was largest in the 2DE group, followed by the 3DSTI group and the MRI group, with a significant difference (P < 0.05; Table 1); inter-group comparison showed the mean of LVEF was significantly different between 2DE group and MRI group (P < 0.05), whereas there was no significant difference between 2DE group and 3DSTI group and between 3DSTI group and MRI group (P > 0.05, respectively). The means of LVESV and LVEDV showed no significant difference among three groups (P > 0.05, respectively).