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 Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen

nachricht New Approach to Treating Chronic Itch
15.08.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>