Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Noninvasive and accurate

20.09.2010
A new method that allows absolute temperature mapping with a previously unmatched accuracy shows promise for biomedical applications

Researchers in Germany and the US have developed a new approach to magnetic resonance imaging (MRI) thermometry using encaged hyperpolarized xenon as a temperature sensor. The method allows absolute temperature mapping with an unprecedented accuracy of 0.1˚C at low and ultralow sensor concentrations.

The new technique, which has the potential to become a helpful tool in clinical diagnostics and therapy monitoring, is presented online in ChemPhysChem. According to Franz Schilling, now a researcher at the Technical University of Munich and lead author of the paper, the method benefits from all the advantages of MRI including its non-invasiveness and the ability to image in any scan orientation with good spatial and temporal resolution.

Many magnetic resonance parameters are inherently temperature-sensitive; for example, proton resonance frequency (PRF), diffusion coefficient or transverse and longitudinal relaxation times. The accuracy of many conventional thermometry methods such as PRF is however limited and although such techniques provide useful relative temperature results, MRI thermometry based on encapsulated hyperpolarized xenon appears to be a more promising technology for in vivo applications because it can be used to map absolute temperatures.

Hydrogen is the most frequently imaged nucleus in MRI, but any nucleus with a net nuclear spin can potentially be imaged, including xenon (129Xe). Such gaseous isotopes must be hyperpolarized before use as their net magnetization is too low to yield a good signal under normal conditions. Schilling and co-workers have introduced xenon sensors as a temperature contrast agent for MRI thermometry to gain both high accuracy and sensitivity. They have achieved this by hyperpolarization through spin exchange optical pumping, which increases the equilibrium net spin polarization by three to four orders of magnitude.

The new technique is based on the temperature-dependent chemical shift of hyperpolarized xenon in a cryptophane-A cage. This shift is linear with a slope of 0.29 ppm per °C, which is almost 30 times higher than that of the proton resonance frequency that is currently used for MRI thermometry. According to Schilling, this new direct mapping concept allows absolute temperature mapping with a previously unmatched accuracy of 0.1˚C at a sensor concentration of 150 µM. But the researchers have also demonstrated an indirect temperature detection technique, via chemical exchange saturation transfer of hyperpolarized xenon (Hyper-CEST, introduced previously by co-author Leif Schröder who currently works at the Leibniz Institute for Molecular Pharmacology in Berlin), which makes temperature mapping with nanomolar agent concentrations as low as 10 nM possible. “This absolute temperature imaging concept offers high temperature accuracy at ultralow agent concentrations”, Schilling says. The new sensors consist of three major components: a cryptophane-A cage for hosting the xenon atom, a linker, and a peptide for sufficient water solubility.

Author: Franz Schilling, Alexander Pines, Lawrence Berkeley National Laboratory, Berkeley (USA), http://www.lbl.gov/

Title: MRI Thermometry Based on Encapsulated Hyperpolarized Xenon

ChemPhysChem 2010, 11, No. 16, Permalink to the article: http://dx.doi.org/10.1002/cphc.201000507

Franz Schilling | Wiley-VCH
Further information:
http://www.lbl.gov/
http://www.wiley-vch.de

Further reports about: MRI Noninvasive magnetic resonance temperature map

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>