Contrast-enhanced ultrasound-modulated laser feedback imaging with microbubbles

A contrast-enhanced ultrasound-modulated laser feedback imaging system is proposed. Compared with traditional ultrasound modulated optical tomography (UOT), the system exhibits high sensitivity and contrast-to-noise (CNR). The usage of the laser feedback technique decreases the photon consumption in imaging. On the other hand, clinical SonoVue microbubbles are used to enhance the attenuation of light in the ultrasound labeled area inside tissues. In experiments, vessels in phantom are imaged and can be distinguished clearly at a penetration depth of 5.5 cm in reflective mode. Using microbubbles, the contrast-to-noise is increased from 0.78 to 3.73 with the lateral imaging resolution of 0.75 mm. Phantoms of different penetration depths with microbubbles in different concentrations were imaged. The experiment results show that with higher microbubbles concentration and thinner depth comes higher CNR. Although a lot remains to be improved, the proposed method is promising for further development toward practical clinical application.