Objective To investigate the diagnostic value of two-dimensional and three-dimensional myocardial strain parameters in rats with isoproterenol-induced chronic heart failure used by 7 T cardiac magnetic resonance tissue tracking imaging technique.Methods Twenty healthy male SD rats of specific pathogen-free class were included and randomly di-vided into control(n =8)and model groups(n =12).The chronic heart failure rat model was prepared by subcutaneous multipoint injection of ISO solution10 mg·kg-1·d-1 for14 consecutive days and subsequent normal diet for4 weeks.Af-ter the establishment of the model,7 T CMR cine sequence scans were performed immediately,and the post-processing soft-ware CVI42.0 was used to analyze and compare the differences in each LV function and myocardial strain parameters be-tween the two groups of rats.At the end of the scan,enzyme-linked immunosorbent assay was performed to detect cardiac troponin I and amino-terminal brain natriuretic peptide precursor levels in serum,and myocardial tissue was stained with hematoxylin-eosin and Masson staining.The diagnostic value of each myocardial strain parameter was evaluated by receiver operating characteristic curves,using serum indexes and pathological staining as the gold standard.Intraclass correlation coefficients and coefficients of variation was used to verify the reproducibility of the left ventricular myocardial strain.Re-sults In the model group,left ventricular end-diastolic volume,left ventricular end-systolic volume,cardiac troponin I and amino-terminal brain natriuretic peptide precursor levels were increased compared with the control group(P<0.05),while left ventricular ejection fraction,left ventricular stroke volume,2D left ventricular global radial strain,2D left ventric-ular global circumferential strain,and 2D left ventricular global longitudinal strain were decreased to different degrees(P<0.05).At the same time,pathological staining showed that the model groups all exhibited myocardial fiber arrangement dis-order,degeneration,necrosis,inflammatory cell infiltration,and interstitial fibrosis.The above results suggested that the CHF model was successfully constructed.The receiver operating characteristic curves showed that the area under the curves of 2D LV myocardial strain parameters were all higher than those of 3D strain parameters,with 2D LVGRS and 2D LVGCS having the highest diagnostic value,while the repeatability of 2D LV strain parameters were all higher than that of 3D strain.Conclusion CMR-TT 2D myocardial strain parameters were overall superior and reproducible to 3D myocardial strain in the diagnosis of CHF.
Chronic heart failureCardiovascular magnetic resonance tissue trackingCardiac strainDiagnostic val-uesRepeatability
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