2023 Biomedical Engineering Letters
Tamar Harary, Yoav Hazan & Amir Rosenthal
Abstract
High-resolution optoacoustic imaging at depths beyond the optical diffusion limit is conventionally performed using a microscopy setup where a strongly focused ultrasound transducer samples the image object point-by-point. Although recent advancements in miniaturized ultrasound detectors enables one to achieve microscopic resolution with an unfocused detector in a tomographic configuration, such an approach requires illuminating the entire object, leading to an inefficient use of the optical power, and imposing a trans-illumination configuration that is limited to thin objects. We developed an optoacoustic micro-tomography system in an epi-illumination configuration, in which the illumination is scanned with the detector. The system is demonstrated in phantoms for imaging depths of up to 5 mm and in vivo for imaging the vasculature of a mouse ear. Although image-formation in optoacoustic tomography generally requires static illumination, our numerical simulations and experimental measurements show that this requirement is relaxed in practice due to light diffusion, which homogenizes the fluence in deep tissue layers.
Fig. In-vivo Tomographic imaging. Figure 8-a: Microscope images of mouse ear (left) and corresponding MIP of the optoacoustic image (right). Figure 8-b: Montage of four different tomographic depth. The depth difference between each consecutive slice was 50 μm. Figure 8-c. Typical raw OA signals from a mouse ear. Scale bar: 1 mm
Tamar Harary, Yoav Hazan & Amir Rosenthal
2023 Biomedical Engineering Letters
https://doi.org/10.1007/s13534-023-00278-8