Concurrent photoacoustic markers for direct three-dimensional ultrasound to video registration

Fusion of video and other imaging modalities is common in modern surgical procedures to provide surgeons with additional information that can provide precise surgical guidance. An example of such uses interventional guidance equipment and surgical navigation systems to register the tools and devices used in surgery with each other. In this work, we focus explicitly on registering three-dimensional ultrasound with a stereocamera system. These surgical navigation systems often use optical or electromagnetic trackers. However, both of these tracking systems have various drawbacks leading to target registration errors of approximately 3mm. Previous work has shown that photoacoustic markers can be used to register three-dimensional ultrasound with video resulting in target registration errors which are much lower than the current state of the art. This work extends this idea by generating multiple photoacoustic markers concurrently as opposed to the sequential method used in the previous work. This development greatly enhances the acquisition time by a factor equal to the number of concurrently generated photoacoustic markers. This work is demonstrated on a synthetic phantom and an ex vivo porcine kidney phantom. The resulting target registration errors for these experiments ranged from 840 to 1360 μm and standard deviations from 370 to 640 μm.