Real-time optoacoustic imaging using near infrared absorbing gold nanoshells for contrast enhancement

Optoacoustic imaging is a new promising medical imaging modality combining the benefits of optical and acoustical methods. The strong scattering behaviour of biological media limits the imaging depth of pure optical modalities like OCT (optical coherence tomography). On the other hand, the field of applications of ultrasound is sometimes limited by the lack of contrast in acoustical impedance between different tissue types. By using the high intrinsic optical contrast of different biological tissue types and making it accessible to acoustical detection by means of the thermoelastic effect, optoacoustics uses the best of the two imaging procedures. In addition, the possibility of using nanoscaled contrast agents makes of optoacoustics an ideal candidate for molecular imaging. Acquisition of optoacoustic images can either be done by scanning a single element transducer over a sample or by using an array of transducers driven by adequate multichannel electronics. In this p aper, a system is presented which allows fast acquisition of optoacoustic images using a Nd:YAG laser for signal generation, a multichannel platform for data read out (DiPhAS, Digital Phased Array System, Fraunhofer IBMT) and gold nanoshells as contrast agent for signal enhancement.