ABSTRACT
Photoacoustic imaging provides high optical contrast and ultrasonic spatial resolution by combining the advantages of ultrasound and optical imaging modalities. Compared with purely optical imaging, photoacoustic imaging furnishes high resolution at depths up to several centimeters. Photoacoustic imaging has been implemented in orthogonal, transmission, and reflection modes. To accomplish deep reflection-mode photoacoustic imaging, two main factors need to be considered: light attenuation and acoustic attenuation. An application for the deep reflection-mode photoacoustic imaging is to image internal organs and the nearby blood vessels. The capability of imaging deeper structures will broaden the application of photoacoustic imaging to deep brain structures beyond the superficial cerebral cortex of an animal, to internal organs of an animal, and even to humans. The combination of higher irradiance and near infrared (NIR) wavelength will generate higher optical fluence in deep regions of tissues, generating stronger photoacoustic waves.
