A wireless capsule with fluorescence imaging capabilities could be swallowed by patients to aid in detection of cancers of the throat and gut. Previous versions of such "video pills" have relied on illuminating patients' innards using a small light source, restricting clinicians to conclusions based on what they can see in the spectrum of visible light. Now researchers from the University of Glasgow, using an advanced semiconductor single-pixel imaging technique, say they have achieved fluorescence imaging in a small pill form for the first time. Fluorescence imaging is a common medical diagnostic tool, and has been used, for example, to identify in patients the rich blood supplies that support cancers and help them to grow, but which can be missed by examination under visible light. However, existing fluorescence imaging technologies are expensive, bulky and have high power requirements, confining the technique to laboratories and hospital examination rooms. The Glasgow capsule incorporated a CMOS single-photon avalanche detector imaging array, miniaturized optical isolation, wireless technology and low-power design. Emitting low-level 468-nm illumination, it consumed 30.9 mW. To demonstrate the capsule's performance, the team imaged fluorescence phantoms incorporating principal tissue fluorophores (flavins) and absorbers (hemoglobin), which mimic closely how cancers are affected by fluorescence in parts of the body such as the intestines, bowel and esophagus. They also demonstrated the utility of marker identification by imaging a 20-μm fluorescein isothiocyanate labelling solution on mammalian tissue. Potentially the device could replace power-hungry and intrusive optical fiber-based endoscopes, and extend the range of clinical examination below the duodenum, the researchers said. "The system we've developed is small enough and power-efficient enough to image the entire human gastrointestinal tract for up to 14 hours," said research associate Mohammed Al-Rawhani. "The system could also be used to help track antibodies used to label cancer in the human body, creating a new way to detect of cancer." The researchers said the technology needs more work before commercial production and clinical use, but they are in early talks with industry to bring the product to market. They are also interested in expanding the imaging capabilities of video-pill systems to new areas such as ultrasound. The research was published in Scientific Reports (doi: 0.1038/srep18591 [open access]).