Autonomous navigation of a magnetic colonoscope using force sensing and a heuristic search algorithm.

This paper presents an autonomous navigation system for cost-effective magnetic-assisted colonoscopy, employing force-based sensors, an actuator, a proportional-integrator controller and a real-time heuristic searching method. The force sensing system uses load cells installed between the robotic arm and external permanent magnets to derive attractive force data as the basis for real-time surgical safety monitoring and tracking information to navigate the disposable magnetic colonoscope. The average tracking accuracy on magnetic field navigator (MFN) platform in x-axis and y-axis are 1.14 ± 0.59 mm and 1.61 ± 0.45 mm, respectively, presented in mean error ± standard deviation. The average detectable radius of the tracking system is 15 cm. Three simulations of path planning algorithms are presented and the learning real-time A* (LRTA*) algorithm with our proposed directional heuristic evaluation design has the best performance. It takes 75 steps to complete the traveling in unknown synthetic colon map. By integrating the force-based sensing technology and LRTA* path planning algorithm, the average time required to complete autonomous navigation of a highly realistic colonoscopy training model on the MFN platform is 15 min 38 s and the intubation rate is 83.33%. All autonomous navigation experiments are completed without intervention by the operator.

Automatic lumen detection and magnetic alignment control for magnetic-assisted capsule colonoscope system optimization.

We developed a magnetic-assisted capsule colonoscope system with integration of computer vision-based object detection and an alignment control scheme. Two convolutional neural network models A and B for lumen identification were trained on an endoscopic dataset of 9080 images. In the lumen alignment experiment, models C and D used a simulated dataset of 8414 images. The models were evaluated using validation indexes for recall (R), precision (P), mean average precision (mAP), and F1 score. Predictive performance was evaluated with the area under the P-R curve. Adjustments of pitch and yaw angles and alignment control time were analyzed in the alignment experiment. Model D had the best predictive performance. Its R, P, mAP, and F1 score were 0.964, 0.961, 0.961, and 0.963, respectively, when the area of overlap/area of union was at 0.3. In the lumen alignment experiment, the mean degrees of adjustment for yaw and pitch in 160 trials were 21.70° and 13.78°, respectively. Mean alignment control time was 0.902 s. Finally, we compared the cecal intubation time between semi-automated and manual navigation in 20 trials. The average cecal intubation time of manual navigation and semi-automated navigation were 9 min 28.41 s and 7 min 23.61 s, respectively. The automatic lumen detection model, which was trained using a deep learning algorithm, demonstrated high performance in each validation index.

Feasibility and safety of a novel magnetic-assisted capsule endoscope system in a preliminary examination for upper gastrointestinal tract.

BACKGROUND AND STUDY AIM: Current capsule endoscopy procedures are ineffective for upper gastrointestinal (GI) tract examination because they do not allow for operator-controlled navigation of the capsule. External controllability of a capsule endoscope with an applied magnetic field is a possible solution to this problem. We developed a novel magnetic-assisted capsule endoscope (MACE) system to visualize the entire upper GI tract. The present study evaluated the safety and feasibility of the MACE system for the examination of the upper GI tract, including the esophagus, stomach, and duodenum. METHODS: The present open clinical study enrolled ten healthy volunteers. All participants swallowed a MACE, and an external magnetic field navigator was used for magnetic capsule manipulation in the upper GI tract. We assessed the maneuverability of the magnetic capsule and completeness of the MACE examination as well as the safety and tolerability of the procedure. RESULTS: The present study enrolled ten healthy volunteers with a mean age and body mass index of 47.7 years and 25.6 kg/m2, respectively. One volunteer withdrew because of difficulty in swallowing the capsule. In total, nine volunteers underwent the MACE examination. The average examination time was 27.1 min. The maneuverability of the capsule was assessed as good and fair in 55.6 and 44.4% of the participants, respectively. The overall completeness of the examination in the esophagus, stomach, and duodenum was 100, 85.2, and 86.1%, respectively. No severe adverse events occurred during this study. All participants exhibited satisfactory tolerance of the MACE examination. CONCLUSION: The MACE system has satisfactory maneuverability and visualization completeness with excellent acceptance and tolerance.

Colonoscopy with magnetic control system to navigate the forepart of colonoscope shortens the cecal intubation time.

BACKGROUND: Colonoscopy is considered the most effective method for diagnosing colorectal diseases, but its application is sometimes limited due to invasiveness, patient intolerance, and the need for sedation. OBJECTIVE: The aim of this study was to improve the problem of loop formation and shorten the cecal intubation time of colonoscopy by using a magnetic control system (MCS). METHODS: Two experienced gastroenterologists, three trainees, and a novice repeated colonoscopy without or with MCS on three colonoscopy training model simulator cases. These cases were divided into introductory (case 2) and challenging levels (cases 4 and 5). The cecal intubation times were recorded. RESULTS: For all cases, the average cecal intubation times for the experienced gastroenterologists with MCS were significantly shorter than without MCS (case 2: 52.45 vs. 27.65 s, p < 0.001; case 4: 166.7 vs. 120.55 s, p < 0.01; case 5: 130.35 vs. 100.2 s, p < 0.05). Those of the trainees also revealed significantly shorter times with MCS (case 2: 67.27 vs. 51 s, p < 0.01; case 4: 253.27 vs. 170.97 s, p < 0.001; case 5: 144.1 vs. 85.57 s, p < 0.001). CONCLUSION: Conducting colonoscopy with MCS is safe and smooth, and shortens the cecal intubation time by navigating the forepart of the colonoscope. In addition, all diagnostic and therapeutic benefits of conventional colonoscopy are retained.

Magnetic control system targeted for capsule endoscopic operations in the stomach--design, fabrication, and in vitro and ex vivo evaluations.

This paper presents a novel solution of a hand-held external controller to a miniaturized capsule endoscope in the gastrointestinal (GI) tract. Traditional capsule endoscopes move passively by peristaltic wave generated in the GI tract and the gravity, which makes it impossible for endoscopists to manipulate the capsule endoscope to the diagnostic disease areas. In this study, the main objective is to present an endoscopic capsule and a magnetic field navigator (MFN) that allows endoscopists to remotely control the locomotion and viewing angle of an endoscopic capsule. The attractive merits of this study are that the maneuvering of the endoscopic capsule can be achieved by the external MFN with effectiveness, low cost, and operation safety, both from a theoretical and an experimental point of view. In order to study the magnetic interactions between the endoscopic capsule and the external MFN, a magnetic-analysis model is established for computer-based finite-element simulations. In addition, experiments are conducted to show the control effectiveness of the MFN to the endoscopic capsule. Finally, several prototype endoscopic capsules and a prototype MFN are fabricated, and their actual capabilities are experimentally assessed via in vitro and ex vivo tests using a stomach model and a resected porcine stomach, respectively. Both in vitro and ex vivo test results demonstrate great potential and practicability of achieving high-precision rotation and controllable movement of the capsule using the developed MFN.

The membrane-associated monooxygenase in the butane-oxidizing Gram-positive bacterium Nocardioides sp. strain CF8 is a novel member of the AMO/PMO family.

The Gram-positive bacterium Nocardioides sp. strain CF8 uses a membrane-associated monooxygenase (pBMO) to grow on butane. The nucleotide sequences of the genes encoding this novel monooxygenase were revealed through analysis of a de novo assembled draft genome sequence determined by high-throughput sequencing of the whole genome. The pBMO genes were in a similar arrangement to the genes for ammonia monooxygenase (AMO) from the ammonia-oxidizing bacteria and for particulate methane monooxygenase (pMMO) from the methane-oxidizing bacteria. The pBMO genes likely constitute an operon in the order bmoC, bmoA and bmoB. The nucleotide sequence was less than 50% similar to the genes for AMO and pMMO. The operon for pBMO was confirmed to be a single copy in the genome by Southern and computational analyses. In an incubation on butane the increase of transcriptional activity of the pBmoA gene was congruent with the increase of pBMO activity and suggested correspondence between gene expression and the utilization of butane. Phylogenetic comparison revealed distant but significant similarity of all three pBMO subunits to homologous members of the AMO/pMMO family and indicated that the pBMO represents a deeply branching third lineage of this group of particulate monooxygenases. No other bmoCAB-like genes were found to cluster with pBMO lineage in phylogenetic analysis by database searches including genomic and metagenomic sequence databases. pBMO is the first example of the AMO/pMMO-like monooxygenase from Gram-positive bacteria showing similarities to proteobacterial pMMO and AMO sequences.