Relationship between myocardial ultrasonic integrated backscatter and mitochondria of the myocardium in dogs

Objective This study aimed to explore the relationship between integrated backscatter (IBS) and mitochondria in arrested myocardium. Methods Twelve open-chest dogs were randomly divided into two groups: one group with cardiac arrest in systole and the other with cardiac arrest in diastole. IBS images at parasternal papillary muscle short-axis view were stored at different time frames (0, 30, and 60 min after cardiac arrest). The values of ultrasonic IBS were obtained using the acoustic densitometry technique. After ultrasound examination, tissue samples of corresponding times were harvested and observed under the transmission electron microscope. The microscopic images were analyzed using a computer imaging analysis system to obtain the stereological parameters of mitochondria. The correlation between IBS and the stereological parameters was analyzed. Results After cardiac arrest, swollen mitochondria with electron-lucent matrix could be observed in some myofibers following the progression of time. The alteration of IBS correlated well with that of mitochondrial stereological parameters, such as volume density (Vv), surface density (Sv), average volume (v¯), average surface area (s¯), and specific surface (Rsv, ratio between surface and volume). Conclusion Mitochondria might be an important scatterer in the myocardium for IBS.