The use of photoacoustic effect is a promising approach for biomedical imaging in living tissues. Photoacoustic tomography (PAT) has been demonstrated to image breast cancer, brain vasculature, arthritis and seizure focus owing to its rich optical contrast and high resolution in a single imaging modality. Here we report a microelectromechanical systems (MEMS)-based intraoperative PAT (iPAT) technique, and demonstrate its ability to accurately map tumors in three-dimension and to inspect the completeness of tumor resection during surgery in a tumor-bearing mouse model. The MEMS imaging probe is small and has the potential to be conveniently used to guide surgical resection of tumors in the breast.

Optical resolution photoacoustic microscopy (ORPAM) represents one of the fastest evolving optical microscopic techniques. However, due to the bulky size and complicated system configuration of conventional ORPAM, it is largely limited to small animal experiments. In this Letter, we present the design and evaluation of a portable ORPAM with a high spatiotemporal resolution and a large field of view. In this system, we utilize a rotatory scanning mechanism instead of the conventional raster scanning to achieve translationless imaging of the probe/samples, making it accessible to the human oral lip and tongue. After phantom evaluation, we applied this system to monitor longitudinal neo-angiogenesis of tumor growth and, for the first time, to the best of our knowledge, image the oral vascular network of humans to show its potential in clinical detection of early-stage oral cancer.

Optical resolution photoacoustic microscopy (ORPAM), benefiting from rich optical contrast, scalable acoustic resolution, and deep penetration depth, is of great importance for the fields of biology and medicine. However, limited by the size and performance of reported optical/acoustic scanners, existing portable/handheld ORPAMs are bulky and heavy, and suffer from low imaging quality/speed. Here, we present an ultracompact ORPAM probe, which is miniature and light, and has high imaging quality. The probe only weighs 20 grams and has an outer size of 22 mm×30 mm×13 mm, a high lateral resolution of 3.8 μm, and an effective imaging domain of 2 mm×2 mm. To show its advantages over existing ORPAMs, we apply this probe to image vasculatures of internal organs in a rat abdominal cavity and inspect the entire human oral cavity.

In this study, we evaluate the penetration capability of light in visible, near-infrared-I (NIR-I) and near-infrared–II (NIR-II) optical windows for photoacoustic macroscale imaging inside 9 biological tissues with three typical penetration depths. An acoustic resolution photoacoustic microscopy is designed to guarantee the consistent experiment conditions except excitation wavelength. Experimental results show that short NIR-II (1000-1150 nm) shows the best performance inside kidney, spleen and liver tissues at all depths, while NIR-I (700-1000 nm) works better for muscle, stomach, heart and brain tissues, especially in deep imaging. This study proposes the optimal selection of illumination wavelengths for photoacoustic macroscale imaging in rat organs, which enables the best signal-to-noise ratio (SNR) of the observed target.