Feasibility study on concurrent optoacoustic tomography and magnetic resonance imaging

Optoacoustic tomography (OAT) and magnetic resonance imaging (MRI) are both endorsed with powerful imaging capabilities. Yet, their seamless integration into a hybrid system may additionally offer highly synergistic and complementary information for concurrent anatomical and functional imaging of living organisms. Herein, we investigate on the possibility of concurrent OAT-MRI image acquisition and provide experimental validation in phantom studies. Simultaneous recording was enabled by designing an MR-compatible copper-shielded spherical ultrasound array that provided real-time volumetric OAT imaging and could be safely introduced into a high-field 9.4 T MRI scanner. The interference between the two modalities was evaluated under commonly employed FLASH and EPI sequences. Phantom experiments revealed that the OAT probe caused minimal distortion in the MRI images, while synchronization of the laser and the MRI pulse sequences enabled defining artifact-free OAT acquisition windows. Good dynamic OAT contrast from superparamagnetic iron oxide nanoparticles, a widely used agent for MRI contrast enhancement, was also observed. The hybrid OAT-MRI system thus provides an excellent platform for cross-validating functional readings of both modalities. Overall, this initial study serves to establish the technical feasibility of developing hybrid OAT-MRI system for biomedical research.