Multimodal optical ultrasound imaging: Real-time imaging under concurrent CT or MRI

Optical ultrasound (OpUS) imaging is an ultrasound modality that utilizes fiber-optic ultrasound sources and detectors to perform pulse-echo ultrasound imaging. These probes can be constructed entirely from glass optical fibers and plastic components, and as such, these devices have been predicted to be compatible with computed tomography (CT) and magnetic resonance imaging (MRI), modalities that use intense electromagnetic fields for imaging. However, to date, this compatibility has not been demonstrated. In this work, a free-hand OpUS imaging system was developed specifically to investigate the compatibility of OpUS systems with CT and MRI imaging systems. The OpUS imaging platform discussed in this work was used to perform real-time OpUS imaging under (separately) concurrent CT and MRI. CT and MRI imaging of the OpUS probe was used to determine if the probe itself would induce artifacts in the CT and MRI imaging, and ultrasound resolution targets and background measurements were used to assess any impact of CT and MRI on the OpUS signal fidelity. These measurements demonstrate that there was negligible interaction between the OpUS system and both the CT and MRI systems, and to further demonstrate this capability, concurrent OpUS-CT and OpUS-MRI imaging was conducted of a tissue-mimicking phantom and a dynamic motion phantom. This work presents a comprehensive demonstration of an OpUS imaging system operating alongside CT and MRI, which opens up new applications of ultrasound imaging in electromagnetically challenging settings.