1E-1 Photoacoustic Microscopy with a 30MHz Array and Receive System

Photoacoustic microscopy is a hybrid imaging modality which captures the contrast advantage of optical imaging with the resolution advantage of ultrasonic imaging. This technique provides great promise for studying the structure and dynamics of tissue microvasculature in development and pathogenesis. In this paper we present results of a new high frequency array based photoacoustic microscopy system (PAM) using an Nd:YAG pumped tunable dye laser, a 30 MHz piezo composite linear array and a custom multi-channel receiver system. Using offline delay and sum beamforming and beamsteering, phantom images were obtained from a 6 mum carbon fiber in water at a depth of 8 mm. The measured axial and lateral spatial resolution of the system was 100 plusmn 5 mum and 45 plusmn 5 mum, respectively. In situ photoacoustic images were obtained of vessels less than 100 mum in diameter at depths of 3 mm below the skin surface in a Sprague Dawley rat