Scientists have developed a camera that can see through the human body.
The camera is designed to help doctors track medical tools known as endoscopes that are used to investigate a range of internal conditions.
The new device is able to detect sources of light inside the body, such as the illuminated tip of the endoscope’s long flexible tube.
Until now, it has not been possible to track where an endoscope is located in the body in order to guide it to the right place without using X-rays or other expensive methods
Light from the endoscope can pass through the body, but it usually scatters or bounces off tissues and organs rather than travelling straight through. This makes it nearly impossible to get a clear picture of where the endoscope is.
The new camera takes advantage of advanced technology that can detect individual particles of light, called photons.
Experts have integrated thousands of single-photon detectors onto a silicon chip, similar to that found in a digital camera.
The technology is so sensitive that it can detect the tiny traces of light that pass through the body’s tissue from the light of the endoscope.
It can also record the time taken for light to pass through the body, allowing the device to also detect the scattered light.
By taking into account both the scattered light and the light that travels straight to the camera, the device is able to work out exactly where the endoscope is located in the body.
Researchers have developed the new camera so that it can be used at the patient’s bedside.
Early tests have demonstrated that the prototype device can track the location of a point light source through 20 centimetres of tissue under normal light conditions.
The project — led by the University of Edinburgh and Heriot-Watt University — is part of the Proteus Interdisciplinary Research Collaboration, which is developing a range of revolutionary new technologies for diagnosing and treating lung diseases.
Proteus is funded by the Engineering and Physical Sciences Research Council.
The research is published in the journal Biomedical Optics Express.
Professor Kev Dhaliwal, of the University of Edinburgh, said: “This is an enabling technology that allows us to see through the human body. It has immense potential for diverse applications such as the one described in this work. The ability to see a device’s location is crucial for many applications in healthcare, as we move forwards with minimally invasive approaches to treating disease.”
Dr Michael Tanner, of Heriot-Watt University, said: “My favourite element of this work was the ability to work with clinicians to understand a practical healthcare challenge, then tailor advanced technologies and principles that would not normally make it out of a physics lab to solve real problems. I hope we can continue this interdisciplinary approach to make a real difference in healthcare technology.”
- G. Tanner, T. R. Choudhary, T. H. Craven, B. Mills, M. Bradley, R. K. Henderson, K. Dhaliwal, R. R. Thomson. Ballistic and snake photon imaging for locating optical endomicroscopy fibres. Biomedical Optics Express, 2017; 8 (9): 4077 DOI: 10.1364/BOE.8.004077
Ultrasound imaging needle to transform heart surgery
Two-dimensional all-optical ultrasound imaging (B-Mode) acquired during the manual translation of the needle tip across a distance of 4 cm. As the needle tip progressed from the high right atrium to the inferior vena cava, the thin foramen ovale manifested as a hypoechoic region between the thick limbus fossae ovalis and the tendon of Todaro (with a diagonal artifact from the ICE catheter and sheath). X-ray fluoroscopic imaging was acquired concurrently (inset).
The revolutionary technology has been successfully used for minimally invasive heart surgery in pigs, giving an unprecedented, high-resolution view of soft tissues up to 2.5 cm in front of the instrument, inside the body.
Doctors currently rely on external ultrasound probes combined with pre-operative imaging scans to visualise soft tissue and organs during keyhole procedures as the miniature surgical instruments used do not support internal ultrasound imaging.
For the study, published today in Light: Science & Applications, the team of surgeons, engineers, physicists and material chemists designed and built the optical ultrasound technology to fit into existing single-use medical devices, such as a needle.
“The optical ultrasound needle is perfect for procedures where there is a small tissue target that is hard to see during keyhole surgery using current methods and missing it could have disastrous consequences,” said Dr Malcolm Finlay, study co-lead and consultant cardiologist at QMUL and Barts Heart Centre.
“We now have real-time imaging that allows us to differentiate between tissues at a remarkable depth, helping to guide the highest risk moments of these procedures. This will reduce the chances of complications occurring during routine but skilled procedures such as ablation procedures in the heart. The technology has been designed to be completely compatible with MRI and other current methods, so it could also be used during brain or fetal surgery, or with guiding epidural needles.”
The team developed the all-optical ultrasound imaging technology for use in a clinical setting over four years. They made sure it was sensitive enough to image centimetre-scale depths of tissues when moving; it fitted into the existing clinical workflow and worked inside the body.
“This is the first demonstration of all-optical ultrasound imaging in a clinically realistic environment. Using inexpensive optical fibres, we have been able to achieve high resolution imaging using needle tips under 1 mm. We now hope to replicate this success across a number of other clinical applications where minimally invasive surgical techniques are being used,” explained study co-lead, Dr Adrien Desjardins (Wellcome EPSRC Centre for Interventional and Surgical Sciences at UCL).
The technology uses a miniature optical fibre encased within a customised clinical needle to deliver a brief pulse of light which generates ultrasonic pulses. Reflections of these ultrasonic pulses from tissue are detected by a sensor on a second optical fibre, giving real-time ultrasound imaging to guide surgery.
One of the key innovations was the development of a black flexible material that included a mesh of carbon nanotubes enclosed within clinical grade silicone precisely applied to an optical fibre. The carbon nanotubes absorb pulsed laser light, and this absorption leads to an ultrasound wave via the photoacoustic effect.
A second innovation was the development of highly sensitive optical fibre sensors based on polymer optical microresonators for detecting the ultrasound waves. This work was undertaken in a related UCL study led by Dr James Guggenheim (UCL Medical Physics & Biomedical Engineering) and recently published in Nature Photonics.
“The whole process happens extremely quickly, giving an unprecedented real-time view of soft tissue. It provides doctors with a live image with a resolution of 64 microns, which is the equivalent of only nine red blood cells, and its fantastic sensitivity allows us to readily differentiate soft tissues,” said study co-author, Dr Richard Colchester (UCL Medical Physics & Biomedical Engineering).
- Malcolm C Finlay, Charles A Mosse, Richard J Colchester, Sacha Noimark, Edward Z Zhang, Sebastien Ourselin, Paul C Beard, Richard J Schilling, Ivan P Parkin, Ioannis Papakonstantinou, Adrien E Desjardins. Through-needle all-optical ultrasound imaging in vivo: a preclinical swine study. Light: Science & Applications, 2017; 6 (12): e17103 DOI: 10.1038/lsa.2017.103