Dancing atoms now understood(culiar quantum mechanical property of su...)

Date:11/26/2008

culiar quantum mechanical property of subatomic particles called "spin". The nuclei of many atoms, most notably hydrogen, spin like tiny tops and possess a magnetic moment like a tiny bar magnet. In NMR and MRI the object under investigation--in medical applications, the patient--is placed inside a strong magnetic field that causes these tiny tops to align with the magnetic field and precess (or wobble, much like a child's top), in the direction of the gravitational field.

For MRI, the strong magnetic field needed for these techniques is generated inside the all too familiar tube that causes many patients claustrophobia, which can require sedation before a procedure. Once inside the magnet, each nucleus broadcasts its identity by emitting radio waves at its unique precession frequency, which depends on its interaction with surrounding atoms as well as the magnetic field strength.

The interaction with surrounding atoms is what makes NMR such a useful tool for chemists and biologists, allowing them to identify different chemical environments and molecular structures.

For MRI, it is the interaction of the nuclei with the magnetic field that is key, as magnetic field strength varies with location, enabling a researcher to code different parts of the body with different frequencies. Through the measurement of the atomic precession frequencies, an MRI radiologist can reconstruct a two-dimensional or three-dimensional image that accurately depicts the interior of a patient's body.

In performing such measurements, scientists often need to invert the nuclei so they are aligned against the magnetic field. Inverting the nuclei of people inside MRI scanners can reveal such things as cancer tumors, whose slightly different interaction with the nuclear spins can be used to detect their presence amid surrounding healthy tissue.

This is where adiabatic processes come into play. The inversions are often done "adiabatically", by
'/>"/>

Contact: Josh Chamot jchamot@nsf.gov 703-292-7730 National Science Foundation Source:Eurekalert

0 GOOD

Page: 1 2 3 4
Related biology news :

1. Super atoms turn the periodic table upside down
2. Diatoms discovered to remove phosphorus from oceans
3. Heftier atoms reduce friction at the nanoscale, study led by Penn researcher reveals