At the University of Glasgow, researchers have made swallowable cameras, or “video pills,” to detect throat and gut cancers. 

In recent years, small, sensing cameras swallowed by patients have been used to capture images of the throat and gut, as compared to more intrusive techniques such as use of endoscopes. These cameras, created by researchers from the University’s School of Engineering, utilize fluorescence imaging to identify the rich blood supplies that support cancers and help them to grow. The team used an advanced semiconductor single-pixel imaging technique to create this pill, which enabled them to utilize the fluorescence imaging technique that is known to be expensive and bulky (and therefore often limited to laboratory settings).

In a paper published in the journal Scientific Reports, researchers describe how they have used fluorescent light for the first time to expand the diagnostic capabilities of the video-pill:

“Fluorescence Imaging (FI) is a powerful technique in biological science and clinical medicine. Current FI devices that are used either for in-vivo or in-vitro studies are expensive, bulky and consume substantial power, confining the technique to laboratories and hospital examination rooms. Here we present a miniaturised wireless fluorescence endoscope capsule with low power consumption that will pave the way for future FI systems and applications. With enhanced sensitivity compared to existing technology we have demonstrated that the capsule can be successfully used to image tissue autofluorescence and targeted fluorescence via fluorophore labelling of tissues. . . . The device has the potential to replace highly power-hungry intrusive optical fibre based endoscopes and to extend the range of clinical examination below the duodenum.”

The project was led by Professor David Cumming in Electronic and Nanoscale Engineering at the University of Glasgow. Cumming participated in a Q&A about the project and their swallowable camera, which they call the “FlouroPill.”

Q: For the detection of cancers of the throat and gut, how effective are endoscopes and other conventional methods?

Cumming: Conventional endoscopes are effective in detection cancer and other abnormalities in the lower and upper part of the Gastrointestinal (GI) tract (esophagus, stomach, the first part of small intestine [duodenum], and the large intestine). However, conventional endoscopes cannot access the 6 meter long small intestine. For this important part of the human body, video pills are the most convenient tool to use.

 

Q: What are some of the other conventional methods that are commonly used to detect cancer of the throat and gut?

Cumming: Cancerous Biomarker detection from biopsies are common way of cancer detection. However, this involves surgical intervention especially in the small intestine.

Q: Prior to your recent discovery, how have video-pills primarily operated when used for the detection of cancers of the throat and gut?

Cumming: In the small intestine where our capsule is meant to operate. The conventional video pills use only standard white light imaging. These pills usually acquire images at 2-3 frames per second. The acquired images is later viewed and examined by a trained physician to spot disease areas.  

Q: How did the University of Glasgow come to discover this new swallowable camera that uses fluorescence imaging?

Cumming: The MST group has a long history with pill format diagnostic devices. One pill that was developed by the MST group is a pH sensing pill for use in the GI tract. The idea of developing a pill that can do more than pH sensing or conventional white light imaging was inspired by the introduction of Olympus endoscope that has fluorescence capability on 2007 for use in the upper and lower GI tract only. Based on our experience on capsules technology, we have foreseen that fluorescence imaging can be also miniaturized and therefore extends its usefulness to reach the 6 meter long small intestine.

Q: Could you describe the functionality of your swallowable camera?

Cumming: The capsule detects cancerous tissues in the small intestine of the GI tract by exciting the tissues using a blue light source (LED) at 460 nm wave length. In response to this light, special molecules known as fluorophores (which exist naturally within tissues or can be introduced externally) emit a green light at 520 nm. The intensity level of the emitted fluorescence determines the health status of the tissues.  

Q: Why is fluorescence imaging an optimal means of detecting cancers of the throat and gut?

Cumming: Fluorescence imaging is currently used in the upper and lower part of the GI tract. Various studies have proven that fluorescence imaging alongside standard imaging increases the specificity of detection as well as reduces the false positive rates.

Q: Could you describe in greater detail the advanced semiconductor single-pixel imaging technique and how that works?

Cumming: Fluorescence imaging is a power-hungry imaging technique that requires high power excitation source. In a capsule format, power is limited to the battery capacity, which precludes the use of high power excitation sources. The solution for this problem is to use a combination of an ultra-sensitive light detectors with a low power excitation source. Single photon avalanche detector (SPAD) is a very sensitive light detector that is fully compatible with mainstream complementary metal oxide semiconductor (CMOS) technology. The highly sensitive SPAD generates a pulse in response to each photon impacting the active area of the device, thus allowing individual fluorescence photons emitted from fluorophores to be counted. The ability of the SAPD to detect fluorescence emission at photon level permits the use of low power LED as an excitation source. In addition to SPAD array integration, CMOS technology allowed us to integrate several electronic blocks that are required for the operation of the capsule. This advantage that is offered by CMOS technology is very critical in the miniaturization process.

Q: For your swallowable cameras, as well as any other video-pills, what would you say are some of the downsides to this technology? And how do you hope to improve this?

Cumming: Power constraints, low fame rate, and low resolution are still the main challenges. However, future designs can exploit more advanced CMOS process technologies to address all of these problems.

Q: What are some of the greatest advantages of the video-pill technology?

Cumming: Video-pills technology in general are the most convenient and minimally-invasive devices available to diagnose and explore the small intestine of the human GI tract.

Q: What are the next steps for your swallowable camera?

Cumming: Technology-wise, we are working on increasing the resolution and frame rate as well as further miniaturizing the pill. We are also building our relationships with clinicians to advance our research.

Q: How do you hope to expand the imaging capabilities of video-pill systems to new areas, such as ultrasound in the near future? Do you have any ideas for how to implement that?

Cumming: We are partners in a research project called Sonopill. Sonopill is also looking at the implementation of a multimodality pill that incorporates multiple imaging and sensing capabilities (i.e., white light imaging, fluorescence imaging, ultrasound imaging, and pH sensing). Further integration using advanced CMOS processes and the micro-fabrication capabilities will make such a device technologically possible.

SonoPill is funded by the UK Engineering and Physical Sciences Research Council.

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