Intelligent magnetic manipulation for gastrointestinal ultrasound.

Diagnostic endoscopy in the gastrointestinal tract has remained largely unchanged for decades and is limited to the visualization of the tissue surface, the collection of biopsy samples for diagnoses, and minor interventions such as clipping or tissue removal. In this work, we present the autonomous servoing of a magnetic capsule robot for in situ, subsurface diagnostics of microanatomy. We investigated and showed the feasibility of closed-loop magnetic control using digitized microultrasound (mu US) feedback; this is crucial for obtaining robust imaging in an unknown and unconstrained environment. We demonstrated the functionality of an autonomous servoing algorithm that uses mu US feedback, both on benchtop trials and in vivo in a porcine model. We have validated this magnetic mu US servoing in instances of autonomous linear probe motion and were able to locate markers in an agar phantom with 1.0 +/- 0.9 mm position accuracy using a fusion of robot localization and mu US image information. This work demonstrates the feasibility of closed-loop robotic mu US imaging in the bowel without the need for either a rigid physical link between the transducer and extracorporeal tools or complex manual manipulation.