Fluorescence can be used for instance to analyze the regulation and expression of genes, to locate proteins in cells and tissues, to follow metabolic pathways and to study the location and migration of cells. Of particular importance is the combination of fluorescence imaging with novel techniques that allow tomographic three-dimensional visualization of objects in living organisms.
At the Helmholtz Zentrum München – German Research Center for Environmental Health together with the Technische Universität München an own institute is concerned with the development and refinement of such new technologies: the Institute for Biological and Medical Imaging headed by Professor Vasilis Ntziachristos.
The quality of optical imaging in tissues is naturally limited, since beyond a penetration depth of a few hundred micrometers the photons are massively scattered due to interactions with cell membranes and organelles which results in blurred images. In the latest issue of the journal Proceedings of the National Academy of Sciences Prof. Ntziachristos and his team, together with colleagues from the Harvard Medical School and the Massachusetts General Hospital in Boston, USA, report on the use of the so-called early arriving photons together with tomographic principles. Early photons are the first photons that arrive onto a photon detector after illumination of tissue by an ultra-short photon pulse and undergo less scattering in comparison to photons arriving at later times. Compared to continuous illumination measurements a combination of these less scattered photons with 360-degree illumination-detection resulted in sharper and more accurate images of mice under investigation.
With this technique, called ‚Early Photon Tomography’ (EPT), the scientists imaged lung tumors in living mice. For this purpose they injected a substance into to the animals, which normally does not fluoresce, but becomes fluorescent after contact with certain cysteine proteases such as cathepsins. The amount of these proteases is enriched in lung tumors which allows fluorescence imaging of the tumor tissue. Comparison with conventional x-ray tomography showed, that EPT is not only a very sensitive technique for imaging of lung tumors in living organisms, but also has the potential to reveal biochemical changes that reflect the progression of the disease, which could not be detected by conventional X-ray imaging.
While early-photons are typically associated with reduced signal available for image formation, the authors demonstrated that due to the wide-field implementation, EPT operates with very small reduction in average signal strength as in conventional tomographic methods operating using continuous light illumination. In this respect EPT is a practical method for significantly improving the performance of fluorescence tomography in animals over existing implementations. At present EPT is practicable only with small animals, but – as stated by the authors of the paper – further development of the equipment can allow niche applications of the technique also with larger organisms including humans.
Michael van den Heuvel | alfa
First transcatheter implant for diastolic heart failure successful
16.11.2017 | The Ohio State University Wexner Medical Center
Theranostic nanoparticles for tracking and monitoring disease state
13.11.2017 | SLAS (Society for Laboratory Automation and Screening)
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
20.11.2017 | Life Sciences
20.11.2017 | Materials Sciences
20.11.2017 | Life Sciences