Combined photoacoustic and ultrasound biomicroscopy

• DOI: 10.1364/oe.17.022041
• Publication Date: 2009-11-17T17:50:28Z
• Authors: Tyler Harrison; Janaka C. Ranasin...; Huihong Lu; Kory Mathewson; Andrew Walsh; Roger J. Zemp
• Keywords: Diagnostic Imaging; Microscopy; Optics and Photonics; Light; Microcirculation; Acoustics; Equipment Design; 01 natural sciences; Carbon; Fingers; Oscillometry; 0103 physical sciences; Image Processing, Computer-Assisted; Microscopy, Electron, Scanning; Humans; Ultrasonics; Ultrasonography

We report on the development of an imaging system capable of combined ultrasound and photoacoustic imaging based on a fast-scanning single-element 25-MHz ultrasound transducer and a unique light-delivery system. The system is capable of 20 ultrasound frames per second and slower photoacoustic frame rates limited by laser pulse-repetition rates. Laser and ultrasound pulses are interlaced for co-registration of photoacoustic and ultrasound images. In vivo imaging of a human finger permits ultrasonic visualization of vessel structures and speckle changes indicative of blood flow, while overlaid photoacoustic images highlight some small vessels that are not clear from the ultrasound scan. Photoacoustic images provide optical absorption contrast co-registered in the structural and blood-flow context of ultrasound with high-spatial resolution and may prove important for clinical diagnostics and basic science of the microvasculature.