Photo acoustic tomography

Photoacoustic tomography (PAT), sometimes referred to as optoacoustic tomography, is defined as cross-sectional or three-dimensional (3D) imaging of a material based on the photoacoustic effect (Wang 2009). Therefore, PAT possesses spatial resolution along the depth dimension and at least one of the other two dimensions. In PAT, light is absorbed by biological tissue and converted to transient heating, which is subsequently converted into an ultrasonic wave due to thermoelastic expansion. Detection of the ultrasonic wave yields a tomographic image. Combining rich optical contrast and scalable ultrasonic resolution, PAT is the only imaging modality capable of providing multiscale high-resolution structural, functional, and molecular imaging of organelles, cells, tissues, and organs in vivo. While functional imaging measures physiological parameters, such as oxygenation and blood flow, molecular imaging senses biomarkers to identify specific cancer cells or detects gene expression products to track gene activations.