ast 3 - D dark - field reflection - mode photoacoustic icroscopy in vivo with a 30 - MHz ultrasound inear array

ihong V. Wang ashington University in St. Louis ptical Imaging Laboratory epartment of Biomedical Engineering t. Louis, Missouri 63130 -mail: [email protected] Abstract. We present an in vivo dark-field reflection-mode photoacoustic microscopy system that performs cross-sectional B-scan imaging at 50 Hz with real-time beamforming and 3-D imaging consisting of 166 B-scan frames at 1 Hz with postbeamforming. To our knowledge, this speed is currently the fastest in photoacoustic imaging. A custom-designed light delivery system is integrated with a 30-MHz ultrasound linear array to realize dark-field reflection-mode imaging. Linear mechanical scanning of the array produces 3-D images. The system has axial, lateral, and elevational resolutions of 25, 70, and 200 m, respectively, and can image 3 mm deep in scattering biological tissues. Volumetric images of subcutaneous vasculature in rats are demonstrated in vivo. Fast 3-D photoacoustic microscopy is anticipated to facilitate applications of photoacoustic imaging in biomedical studies that involve dynamics and clinical procedures that demand immediate diagnosis. © 2008 Society of Photo-Optical Instrumentation Engineers. DOI: 10.1117/1.2976141