| Objective:To quantitative assessment myocardial infarct area and segmental transmural extent of acute myocardial infactions using delayed contrast-enhanced magnetic resonance imaging (DE-MRI).And compared the changes in three-dimensional strain parameters in different degree infarct area and segmental transmural extent using three dimensional speckle tracking echocardiography (3D-STE), to find the most sensitive indicator to reflect the myocardial infarct area and segmental transmural extent.Methods:Twenty-six patients were examined with DE-MRI 7-21 days after a first AMI. DE-MRI confirmed the infarct location, global infarct size of LV and the transmural infarct extent of each segment:①Patient were divided into groups depending on the global myocardial infarct area:small myocardial infarcts of <10%,medium myocardial infarcts of 10% to 30% and large myocardial infarcts of>30%.②All segments in midventricular level divided into groups depending on the transmural infarct extent :Normal segments, Subendocardial infarct segments of <50% and transmural infarct segments of≥50%.LV global longitudinal peak systolic strain(GLS), LV global circumferential peak systolic strain (GCS), LV global radial peak systolic strain(GRS) and LS, CS,RS of segments in midventricular level were measured in all subjects by 3D-STE from the apical full-volume image; The myocardial motion of each segment was evaluated according to the standard American Society of Echocardiography wall motion scoring system, which assigns a wall motion score ranging from 1 to 4 to describe normokinesia, hypokinesia, akinesia, and dyskinesia, respectively, and wall motion score index (WMSI) was calculated as the ratio of the sum of wall motion score over total segments. LV ejection fraction was assessed by Simpson's method. The correlation between MIA and GLS,GCS,GRS,LVEF,WMSI were analyzed respectively. Receiver-operating characteristic (ROC) curves was used to evaluate the diagnostic value of quantitative parameters.Results:①Compared with small infarct group, all global parameters in large infarct group and GLS,GCS in medium infarct group have significant differences (all P<0.05). No significant differences were found in GRS,EF,WMSI between medium infarct group and small infarct group(all P>0.05);Compared with medium infarct group, GLS,GCS,GRS,WMSI in large infarction group have significantly differences(all P<0.05),but there was no significant difference in EF(P >0.05).②Linear regression analysis showed that GLS, GCS, GRS, WMSI and LVEF had a significant correlation with the MIA(r1=0.86, P1<0.01; r2=0.81,P2<0.01; r3=-0.71,P3<0.01;r4=0.64, P4<0.01; r5=-0.66,P5<0.01 respectively).③According to the ROC curve, the quantitative parameter GLS was most valuable in predicting the myocardial infarct size. (MIA≥10%, AUC=0.840; MIA> 30 %,AUC=0.922).④At the segmental level, compare with normal segments, LS,CS reduced in medium infarct (P<0.05), but there was no significant difference in RS(P>0.05),LS,CS,RS in transmural segments were significantly decreased (P<0.05);Compared with non-transmural segments, LS,CS,RS reduced in transmural segments (P<0.05)⑤GLS,GCS,GRS within researchers or between researchers were 11.24±4.38 and 9.54±4.48,10.76±4.15 and 10.67±4.66,14.24±5.02 and 11.23±3.44; LS,CS,RS in midventricular level within researchers or between researchers were 13.41±5.41 and 9.71±4.50,11.33±4.65 and 12.63±4.82,14.58±6.16 and 12.43±3.94.Conclusion:①Global Circumferential and longitudinal strains by 3D-STE correlate with myocardial infarct area and significantly differentiate among large, medium, and small myocardial infarcts.②global strain parameter from 3D-STE is a valuable predictor of the segmental transmural extent of myocardial infarction. |
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