Segmental and transmural motion of the rat myocardium estimated using quantitative ultrasound with new strategies for infarct detection

Figures

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  FIGURE 1. Ultrasound examination of the rat heart. (A) PLAX view of the left ventricle scanned using the MS-250 probe. (B) Typical acquired image in the PLAX view. PLAX, parasternal long axis.

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  FIGURE 2. Flowchart of regional and layer-specific LV segmentation. (A) B-mode image; (B) initial borders were manually selected; (C) initial borders were interpolated; (D) Endo/Epi-Ap was defined as the farthest point from Endo/Epi-BMp; (E) each upper or bottom sub-borders were divided into three equal-length segments; (F) the borders of six LV segments were connected. Each myocardial segment was divided into three (G) and 10 (H) layers through cross-line division. LV, left ventricle; Endo/Epi-Ap, endocardial/epicardial apical point; Endo/Epi-BMp, endocardial/epicardial basal middle point; A-SEP, apical septum, M-ANT-SEP, middle anteroseptal; B-ANT-SEP, basal anteroseptal; A-LAT, apical lateral; M-INF-LAT, middle inferolateral; B-INF-LAT, basal inferolateral; EpiL, epicardial layer; MidL, middle layer; EndoL, endocardial layer; L, layer.

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  FIGURE 3. Results of optimal overlap selection with different overlap values against (A) SNR, signal-to-noise ratio; (B) DCCCC, displacement-compensated cross-correlation coefficient.

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  FIGURE 4. Quantitative comparisons of segmental CDA values among the sham, MI, and IR groups at 1 day (A) and 28 days (B) after the rat model establishment. CDA, cumulative displacement in the axial direction; MI, myocardial infarction; IR, ischemia–reperfusion; A-LAT, apical lateral; A-SEP, apical septum; M-INF-LAT, middle inferolateral; M-ANT-SEP, middle anteroseptal; B-INF-LAT, basal inferolateral; B-ANT-SEP, basal anteroseptal. Positive and negative values on the y-axis represent moving downwards and upwards, respectively; × , mean displacement value of the current boxplot; #, statistically significant difference at p < 0.05 versus MI1; *, p < 0.05; **, p < 0.01.

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  FIGURE 5. Qualitative comparisons of transmural LV systolic motion among all groups. (A–F) Calculated CDA map selected from Sham1, MI1, IR1, Sham28, MI28, and IR28 groups, respectively; CDA, cumulative displacement in the axial direction; MI, myocardial infarction; IR, ischemia–reperfusion. Red and blue colors represent downward and upward movements, respectively. White arrows indicate the segments with obvious reduction in myocardial motion.

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  FIGURE 6. Quantitative layer-specific comparisons of transmural CDA values among Sham1, MI1, and IR1 groups. CDA, cumulative displacement in the axial direction; MI, myocardial infarction; IR, ischemia–reperfusion; (A) A-LAT, apical lateral; (B) A-SEP, apical septum; (C) M-INF-LAT, middle inferolateral; (D) M-ANT-SEP, middle anteroseptal; (E) B-INF-LAT, basal inferolateral; (F) B-ANT-SEP, basal anteroseptal. Positive and negative values on the y-axis represent moving downwards and upwards, respectively; × , mean displacement value of the current boxplot; *, statistically significant difference at p < 0.05 versus Sham1; **, statistically significant difference at p < 0.01 versus Sham1.

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  FIGURE 7. Quantitative layer-specific comparisons of transmural CDA values among Sham28, MI28, and IR28 groups. CDA, cumulative displacement in the axial direction; MI, myocardial infarction; IR, ischemia–reperfusion; (A) A-LAT, apical lateral; (B) A-SEP, apical septum; (C) M-INF-LAT, middle inferolateral; (D) M-ANT-SEP, middle anteroseptal; (E) B-INF-LAT, basal inferolateral; (F) B-ANT-SEP, basal anteroseptal. Positive and negative values on the y-axis are the same as shown in Figure 4. × , mean displacement value of the current boxplot; *, statistically significant difference at p < 0.05 versus Sham28; **, statistically significant difference at p < 0.01 versus Sham28.

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  FIGURE 8. Quantitative TMI comparisons of transmural CDA values among all groups. CDA, cumulative displacement in the axial direction; MI, myocardial infarction; IR, ischemia–reperfusion; (A) A-LAT, apical lateral; (B) A-SEP, apical septum; (C) M-INF-LAT, middle inferolateral; (D) M-ANT-SEP, middle anteroseptal; (E) B-INF-LAT, basal inferolateral; (F) B-ANT-SEP, basal anteroseptal; TMI, transmural motion index. × , mean TMI value of the current boxplot; *, p < 0.05; **, p < 0.01.

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  FIGURE 9. Average CDA plots of the 10 layers and the TMI value of the M-ANT-SEP wall for the groups at 1 day (A) and 28 days (B) after the rat model establishment. MI, myocardial infarction; IR, ischemia–reperfusion; M-ANT-SEP, middle anteroseptal; EpiL, epicardial layer; MidL, middle layer; EndoL, endocardial layer.

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  FIGURE 10. Results of Masson’s staining (×100) obtained from the apical, middle, and basal parts of the rat myocardium from the Sham, MI, and IR groups. Green arrows indicate the fibrous tissue. MI, myocardial infarction ; IR, ischemia–reperfusion.