Toward noninvasive optoacoustic imaging of whole-heart dynamics in mice

High-speed volumetric optoacoustic tomography (VOT) offers powerful means for noninvasive, detailed visualization of rapid cardiac dynamics in mice. However, current implementations suffer from non-uniform light delivery into the thoracic area, which results in diminished penetration depth, limited field-of-view, and compromised quantification abilities. In this work, we devised a new VOT approach featuring hexagonally-shaped light delivery optimized for whole-heart imaging and an expedited imaging speed of 200 volumes per second using a custom-made spherical array transducer. The enhanced imaging performance was confirmed with calibration phantoms and noninvasive imaging of the murine heart. We capitalized on the reduced hemoglobin absorption in the second near-infrared (NIR-II) spectral window to mitigate the strong light attenuation by whole blood within the cardiac chambers while further employing copper sulfide nanoparticles featuring a strong NIR-II absorption to quantify cardiac functional parameters across the entire heart in vivo. The new approach can thus facilitate the monitoring of cardiac abnormalities and assessment of therapeutic interventions.