WASHINGTON: Researchers at the Beth Israel Deaconess Medical Center in Boston, US, have come up with an innovative way of using MRI to create images of fluid flow inside the body.

Magnetic resonance imaging (MRI) produces detailed images of the inner body. It works by aligning the nuclei of atoms using a powerful magnetic field, and then zapping them with radio waves.

The way the nuclei re-emit radio waves can reveal all kinds of clues about their environment - for instance, its chemical composition.

Now, David Alsop, a professor of radiology at the institute has found out a way to uncover how a sample of nuclei is moving, within a fluid.

This can be done by zapping them with a focused sequence of radio pulses, which distinguishes them from similar nuclei nearby. It can then be seen how they move when the pulses are re-emitted. According to professor Alsop, the technique could be particularly useful for studying the detailed pattern of blood flow within the brain.

MRI is used to distinguish pathologic tissue (such as a brain tumour) from normal tissue. One advantage of an MRI scan is that it is harmless to the patient. It uses strong magnetic fields and non-ionizing radiation in the radio frequency range. Compare this to CT scans and traditional X-rays which involve doses of ionizing radiation and may increase the risk of malignancy, especially in a foetus.