Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Medical imaging relaxes to brighten up

09.04.2002


Protein packaging may enhance MRI contrast.



Images of body tissues and organs could soon be brighter and sharper thanks to a technique developed by Italian chemists. They have made the chemical contrast agents used in magnetic resonance imaging (MRI) produce a stronger signal by trapping them in protein cages just 12 millionths of a millimetre (nanometres) or so widesup>1.

Such improvements increase the contrast of the images, so they should reveal more detailed information, enabling doctors to better discriminate between different tissue types. The researchers, Silvio Aime and co-workers at the University of Turin, hope to persuade their protein cages to latch onto particular cells, as this would help them to pinpoint diseased tissues.


One of the best MRI contrast agents is a molecule containing atoms of the element gadolinium. Injected into the bloodstream, the gadolinium compound accumulates in abnormal tissues such as scar tissue and tumours, so they become brighter in MRI scans. The agent is ultimately passed out of the body in urine.

Making gadolinium contrast agents brighter is a subtle business. Gadolinium enhances MRI contrast because it helps water molecules to relax. The MRI signal comes from water molecules that have been stimulated into an excited state by radio waves. The quicker the water molecules return to their normal state, the stronger the signal. Gadolinium assists in this process.

How well gadolinium does its job depends on the molecules around it. Proteins can amplify the relaxation induced by gadolinium because chemicals on their surface interact with water molecules. Aime’s team found they got better MRI contrast by keeping standard gadolinium contrast agents close to proteins.

Nature provided them with a ready-made protein cage in the form of ferritin, a shell of 24 protein molecules with a cavity about 7.5 nanometres across. Liver cells store iron inside ferritin, packing up to 4,500 iron atoms into its hollow interior.

The Italian team used a stripped-down version of ferritin known as apoferritin. They trapped the gadolinium contrast agent inside the cavity by first splitting the capsule open in acid and then reforming it in neutral solution containing the gadolinium compound. Each apoferritin compartment holds about ten of these gadolinium molecules.

Crucially, apoferritin’s walls are riddled with channels that are wide enough to let water in and out but too narrow to let gadolinium through. This exchange of water between the inside and the outside is essential for increasing its relaxation rate. Apoferritin seems to enhance gadolinium’s relaxation about 20-fold, the team reports.

They haven’t yet discovered how this translates into changes in MRI contrast, however. The clinical usefulness of the new approach will depend on many other factors, such as how efficiently apoferritin-bound gadolinium can be transported round the body, and how easily it can be cleared from the bloodstream.

References
  1. Aime, S., Frullano, L. & Crich, S.G. Compartmentalization of a gadolinium complex in the apoferritin cavity: a route to obtain high relaxivity contrast agents for mangetic resonance imaging. Angewandte Chemie International Edition, 41, 1017 - 1019, (2002).


PHILIP BALL | © Nature News Service

More articles from Health and Medicine:

nachricht Hot cars can hit deadly temperatures in as little as one hour
24.05.2018 | Arizona State University

nachricht 3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>