Magnetically guided capsule endoscopy

Abstract

Wireless capsule endoscopy (WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal (GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which was previously inaccessible to classical flexible endoscopy. As a diagnostic tool, it allows to localize the sources of bleedings in the middle part of the gastrointestinal tract and to identify diseases, such as inflammatory bowel disease (Crohn's disease), polyposis syndrome, and tumors. The screening and diagnostic efficacy of the WCE, especially in the stomach region, is hampered by a variety of technical challenges like the lack of active capsular position and orientation control. Therapeutic functionality is absent in most commercial capsules, due to constraints in capsular volume and energy storage. The possibility of using body-exogenous magnetic fields to guide, orient, power, and operate the capsule and its mechanisms has led to increasing research in Magnetically Guided Capsule Endoscopy (MGCE). This work shortly reviews the history and state-of-art in WCE technology. It highlights the magnetic technologies for advancing diagnostic and therapeutic functionalities of WCE. Not restricting itself to the GI tract, the review further investigates the technological developments in magnetically guided microrobots that can navigate through the various air-and fluid-filled lumina and cavities in the body for minimally invasive medicine.

Medical Technologies and Challenges of Robot-Assisted Minimally Invasive Intervention and Diagnostics

“…Other research focuses on the ability to combine the visualization abilities of currently sold capsule systems with therapeutics and better localization abilities. A 2017 review highlights many of the important developments in the field up until the present [104].…”

“…To investigate potentially less invasive methods, swimming-based and magnetic capsule actuation methods have been developed using liquid stomach distension, see Figure 8-(d) [97]. Early trials reported the use of a handheld magnet to orient a capsule with another magnet inside a water-distended stomach, but these methods are largely nonintuitive to use, leading to the use of robotic methods to reduce fatigue and improve usability/precision [104]. An alternative to the use of moving permanent magnets is electromagnetic coil systems.…”

“…[97]. Image mosaic courtesy of [104] The high power requirements as well as concerns with fragility, mechanical complexity, sterilizability, and possible organ trauma have resulted in more recent research moving away from internal actuation methods to magnetic actuation methods.…”

“…Magnets can be used to drag/orient capsules [110] or to create internal motion for some sort of swimming motion. This includes flexible-tailed fish-like capsules or rotation-induced spiral actuators [104].…”

“…While capsule pills have succeeded in providing visualization capabilities, most commercial systems have done little to move beyond diagnostics to explore capsule therapeutics. Shamshudin et al's review [104] highlights some of the major challenges of the field and room for future growth: Biopsy or other therapeutic capabilities would greatly enhance the abilities of capsule systems. Currently, systems have shown the possibility of therapeutic bacteria or drug release using applied magnetic fields or shape memory alloys, but there is still research ongoing to make these and similar systems realizable clinically.…”