Three-dimensional photoacoustic tomography of small animal brain with a curved array transducer

We present the application of an optimized curved array photoacoustic tomographic imaging system, which can provide rapid, high-resolution photoacoustic imaging of small animal brains. The system can produce a B-mode, 90-degree field-of-view image at sub-200 μm resolution at a frame rate of ~1 frame/second when a 10-Hz pulse repetition rate laser is employed. By rotating samples, a complete 360-degree scan can be achieved within 15 seconds. In previous work, two-dimensional ex vivo mouse brain cortex imaging has been reported. In the current work, we report three-dimensional small animal brain imaging obtained with the curved array system. The results are presented as a series of two-dimensional cross-sectional images. Besides structural imaging, the blood oxygen saturation of the animal brain cortex is also measured in vivo. In addition, the system can measure the time-resolved relative changes in blood oxygen saturation level in the small animal brain cortex. Finally, ultrasonic gel coupling, instead of the previously adopted water coupling, is conveniently used in near-real-time 2D imaging.