Fig. 2.

Characterization of the multimodal imaging performance. (a) Phantom experiment for characterizing the sensitivity of MROT to different concentration levels of ICG and GdDOTA solution. A tubing with 0.28 mm inner diameter (indicated in red) running the contrast agent was moved into the FOV of the spherical transducer array. (b) The tubing containing 10 µM concentration of ICG can be visualized with OAT at 800 nm excitation wavelength. (c) The corresponding ToF MRI image of 2.5 mM concentration of GdDOTA. (d) Intensity of the recorded OAT signal as a function of the ICG concentration. Minimal optoacoustic signal was detected at the concentration of 0.25 µM (indicated in an inset). (e) Similarly, the MRI sensitivity was characterized with varying GdDOTA concentrations.