| Objective:Ultrasonic integrated backscatter(IBS)is produced by ultrasound backscattering from ultrastructures. Identifying which ultrastructure in the myocardium is the major scatterer remains an unsolved problem. Since mitochondria are abundant in the myofibers, we postulated mitochondria might be one of the major scatterers. Furthermore, mitochondria are so sensitive that it may change firstly in morphology when the myofibers are subjected to some lesion factors. So, we designed an experiment at the level of sub-cells to cause mitochondrial morphological alteration by cardiac anoxia and to explore the relationship between the values of myocardial ultrasonic integrated backscatter and mitochondria. Then we can take further steps to determine whether mitochondria are one of the major scatterers in the myocardium.Methods:Hearts of 12 dogs were arrested at systolic or diastolic state using Hyper-calcium or hyper-potassium solution and cardiac radio-frequency images were acquired at points of 0, 30 and 60 minutes after arrest. IBS were obtained with "Acoustic Densitometry Technique". Tissue specimens of corresponding time were excised and observed under electronic microscope. Stereological parameters of the mitochondria were measured with Computer Imaging Analysis System.Results:With arresting time prolongation, the swollen mitochondria with electron-lucent and cristallin-chaotic appeared in some myofibers. Mitochondrial volume density (Vv), surface density(Sv), average volume(), average surface area () all increased(P<0.05); specific surface (Rsv) decreased(P<0.05) but numerical density(Nv) changed little(P>0.05). IBS decreased at both states(P<0.05). Alteration of IBS correlated well with those of Vv, Sv, , , Rsv.Conclusions:The mitochondria may be an important scatterer in the myocardium. |
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