Intravascular Optical Coherence Tomography Utilizing a Miniature Piezoelectric-Driven Probe.

Intravascular optical coherence tomography (IV-OCT) is crucial for evaluating lumen dimensions and guiding interventional procedures. However, traditional catheter-based IV-OCT faces challenges in achieving precise and full-field 360° imaging in tortuous vessels. Current IV-OCT catheters that employ proximal actuators and torque coils are susceptible to non-uniform rotational distortion (NURD) in tortuous vessels, while distal micromotor-driven catheters struggle with complete 360° imaging due to wiring artifacts. In this study, we developed a miniature optical scanning probe with an integrated piezoelectric-driven fiber optic slip ring (FOSR) to facilitate smooth navigation and precise imaging within tortuous vessels. The FOSR features a coil spring-wrapped optical lens serving as a rotor, enabling efficient 360° optical scanning. The structurally-and-functionally-integrated design significantly streamlines the probe (with a diameter of 0.85 mm and a length of 7 mm) while maintaining an excellent rotational speed of 10,000 rpm. High-precision 3D printing technology ensures accurate optical alignment of the fiber and lens inside the FOSR, with a maximum insertion loss variation of 2.67 dB during probe rotation. Finally, a vascular model demonstrated smooth probe insertion into the carotid artery, and imaging of oak leaf, metal rod phantoms, and ex vivo porcine vessels verified its capabilities for precise optical scanning, comprehensive 360° imaging, and artifact elimination. The FOSR probe exhibits small size, rapid rotation, and optical precision scanning, rendering it exceptionally promising for cutting-edge intravascular optical imaging techniques.

Multistage adaptive control strategy based on image contour data for autonomous endoscope navigation.

The physician burnout, poor ergonomics are hardly conducive to the sustainability and high quality of colonoscopy. In order to reduce doctors' workload and improve patients' experiences during colonoscopy, this paper proposes a multistage adaptive control approach based on image contour data to guide the autonomous navigation of endoscopes. First, a fast image preprocessing and contour extraction algorithms are designed. Second, different processing algorithms are developed according to the different contour information that can be clearly extracted to compute the endoscope control parameters. Third, when a clear contour cannot be extracted, a triple control method inspired by the turning of a novice car driver is devised to help the endoscope capture clear contours. The proposed multistage adaptive control approach is tested in an intestinal model over a variety of curved configurations and verified on the actual colonoscopy image. The results reveal the success of the strategy in both straight sections of this intestinal model and in tightly curved sections as small as 6 cm in radius of curvature. In the experiment, processing time for a single image is 20-25 ms and the accuracy of judging steering based on intestinal model pictures is 96.7%. Additionally, the average velocity reaches 3.04 cm/s in straight sections and 2.49 cm/s in curved sections respectively.