Polarized Microwave-Induced Thermoacoustic Imaging for Detection of Dilated Cardiomyopathy In Vivo.

Abstract

Altered myocardial fiber arrangement is a hallmark feature in the early stages of dilated cardiomyopathy (DCM). However, current medical imaging modalities have limitations in resolving microstructural changes within the myocardium. In this study, we introduce a high-spatiotemporal-resolution polarized microwave-induced thermoacoustic imaging (P-MTAI) technique for in vivo detection of myocardial fiber rearrangement in DCM. Leveraging the anisotropic arrangement and orientation of myocardial fibers, the technique analyzes thermoacoustic signals generated by stimulating the myocardium with linearly polarized pulsed microwaves from four orthogonal directions, enabling the assessment of its spatial microstructure. To mitigate motion artifacts induced by cardiac contraction, the system acquires thermoacoustic images at a frame rate of 100 Hz. The end-diastolic phase, corresponding to maximal cardiac relaxation, is identified from consecutively acquired frames across multiple cardiac cycles, and frames from this phase are selected for polarization analysis. A derived parameter, the degree of microwave absorption anisotropy (DOMA), is employed to quantify the transition of myocardial fiber arrangement from an organized to a disorganized state. The efficacy of P-MTAI was validated in a rabbit model of DCM. Results indicate a statistically significant reduction in myocardial DOMA values in DCM-affected rabbits compared to healthy controls. These results demonstrating the potential of P-MTAI for early-stage DCM detection. This study provides a novel approach for the early detection of dilated cardiomyopathy, with significant clinical translational potential and application prospects.