Label-free, high-spatiotemporal resolution microwave-induced thermoacoustic imaging for functional cardiac phenotyping and myocarditis detection

Cardiovascular diseases are the leading global cause of mortality, underscoring the need for imaging tools that enable early and accurate diagnosis. Current modalities are limited in their ability to simultaneously capture anatomical, functional, and tissue-level properties without exogenous contrast agents. Here, we introduce microwave-induced thermoacoustic imaging (MTAI) as a noninvasive, label-free technique that provides high-spatiotemporal resolution imaging of cardiac structure, mechanical function, and intrinsic conductivity. By detecting ultrasound waves generated from transient microwave energy absorption, MTAI permits real-time visualization of myocardial wall motion, chamber dimensions, and tissue composition. Crucially, we demonstrate the ability of MTAI to detect and characterize myocarditis in mice, leveraging its sensitivity to inflammation-driven conductivity changes—without the need for contrast enhancement. The results establish MTAI as a comprehensive, radiation-free imaging platform for preclinical research, with strong potential for early and differential diagnosis of inflammatory heart disease.