Abstract
Early diagnosis of colorectal cancer substantially improves survival. However, over half of cases are diagnosed late due to the demand for colonoscopy—the ‘gold standard’ for screening—exceeding capacity. Colonoscopy is limited by the outdated design of conventional endoscopes, which are associated with high complexity of use, cost and pain. Magnetic endoscopes are a promising alternative and overcome the drawbacks of pain and cost, but they struggle to reach the translational stage as magnetic manipulation is complex and unintuitive. In this work, we use machine vision to develop intelligent and autonomous control of a magnetic endoscope, enabling non-expert users to effectively perform magnetic colonoscopy in vivo. We combine the use of robotics, computer vision and advanced control to offer an intuitive and effective endoscopic system. Moreover, we define the characteristics required to achieve autonomy in robotic endoscopy. The paradigm described here can be adopted in a variety of applications where navigation in unstructured environments is required, such as catheters, pancreatic endoscopy, bronchoscopy and gastroscopy. This work brings alternative endoscopic technologies closer to the translational stage, increasing the availability of early-stage cancer treatments.
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Data availability
All data supporting the findings of this study are available within the Article and its Supplementary Information files.
Code availability
All the algorithms and mathematical methods used in this study are available within the Article and its Supplementary Information. The computer code is available from the corresponding author on reasonable request.
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Acknowledgements
The research reported in this Article was supported by the Royal Society, Cancer Research UK (CRUK) Early Detection and Diagnosis Research Committee (award no. 27744), the National Institute of Biomedical Imaging, Bioengineering of the National Institutes of Health (NIH; award no. R01EB018992), by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 818045) and the Italian Ministry of Health funding programme ‘Ricerca Sanitaria Finalizzata 2013—Giovani Ricercatori’ project no. PE-2013-02359172. Any opinions, findings and conclusions or recommendations expressed in this Article are those of the authors and do not necessarily reflect the views of the Royal Society, CRUK, NIH, ERC or the Italian Ministry of Health.
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J.W.M. and B.S. worked together throughout the project and co-authored the paper. In the following, an asterisk indicates (co-)leadership on a task. J.W.M.*, B.S.*, P.V.* and A.A. worked on conceptualization. J.W.M. worked on data curation and formal analysis. P.V.*, K.L.O.*, A.A.* and V.S.* worked on funding acquisition. B.S.*, J.W.M.* and J.C.N.* worked on investigation. B.S.*, J.W.M.*, J.C.N.*, K.L.O., A.A. and V.S. worked on methodology. B.S.* and P.V.* worked on project administration. P.V.* and J.C.N.* worked on resources. J.W.M.* and B.S.* worked on software. P.V. worked on supervision. B.S.*, J.W.M.*, P.V.* and J.C.N.* worked on validation. J.W.M.* and B.S.* worked on visualization. J.W.M.* and B.S.* worked on writing the initial draft. B.S.*, J.W.M.*, P.V., J.C.N., K.L.O., A.A. and V.S. worked on writing, reviewing and editing the manuscript.
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Extended data
Extended Data Fig. 1 Validation of the magnetic manipulation algorithm.
The first experiment sort to verify that the closed-loop controller could manipulate the EPM in such a way that the magnetic torque imparted on the MFE would accurately and precisely control the direction of the MFE camera frame. The experiment was carried out on a testing rig consisting of a straight tract of latex colon model (M40, Kyoto Kagaku Co., Ltd) with a LED reference point mounted at one end of the tract. The MFE was then positioned so that its camera could observe the LED (10cm separation distance). A simple image-thresholding algorithm was then used to detect the LED in the MFE image. The robot closed-loop controller, based on a proportional-derivative control approach, thoroughly described in Intelligent Control and Autonomous Navigation, autonomously steered the MFE to trace two predefined motions in the image plane, arranged in either a sinusoidal or circular trajectory with the tracked LED point used as a positional reference. Upon the LED aligning to the first pixel point of the trajectory, the target was updated to the next point along the trajectory and repeated until complete (Supplementary Video 2). Each trajectory was repeated 5 times with the circular path having an average pixel position error of 6.54 ± 0.94, and the sinusoidal path having an average pixel position error of 7.73 ± 1.45. Given a pixel-to-millimetre-conversion described in Supplementary Fig. 2, this experiment shows that the orientation controller can steer the MFE image plane towards a target, with a positional accuracy of about 5mm.
Extended Data Fig. 2 Example of lumen detection algorithm.
where (a) is the original MFE image and (b) is the segmented centre of the colon and (c) is the centre mass point of the lumen (xl,yl) which will be steered to the centre of image (xC,yC) and (d) represents the change in linear velocity of the MFE, given the distance between the estimated lumen (xl,yl) and centre of image (xc,yc).
Extended Data Fig. 3 Feature detector for autonomous navigation.
The action of the autonomous controller is dependent on the absence, or presence of a lumen. When no clear lumen is present in the MFE image (Extended data Fig. 3–a), the FAST feature detector will return a low number of features, with a feature defined as a discernible edge in the image. Features are shown here as green circles. When a clear lumen is present in the MFE image (Extended data Fig. 3–b), the FAST feature detector will instead return a high number of features.
Supplementary information
Supplementary Information
Supplementary Figs. 1–5, algorithms 1–3, equations (1) and (2), Videos 1–3 and Datasets 1 and 2.
Supplementary Video 1
Concept overview.
Supplementary Video 2
Closed-loop controller validation.
Supplementary Video 3
Results.
Supplementary Data 1
Data—benchtop.
Supplementary Data 2
Data—in vivo.
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Martin, J.W., Scaglioni, B., Norton, J.C. et al. Enabling the future of colonoscopy with intelligent and autonomous magnetic manipulation. Nat Mach Intell 2, 595–606 (2020). https://doi.org/10.1038/s42256-020-00231-9
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DOI: https://doi.org/10.1038/s42256-020-00231-9
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