New "Gating" Device Improves Imaging of Heart and Lungs

Magnetic resonance imaging (MRI) of the heart and lungs is a valuable diagnostic tool in the medical industry, but the detailed images it produces are often marred by artefacts (unwanted signals) created by the motion of cardiac and respiratory cycles.

A team of inventors at Oxford University has now developed a method of suppressing MRI artefacts to a negligible level. This has potential to allow more precise conclusions to be made from a small number of experimental trials, with obvious potential within the pharmaceutical industry, both to accelerate research work and to improve the robustness and quality of screening data upon which key project decisions can be made.

Cardiac and thoracic MRI of small animals, such as mice, requires high spatial resolution in order to resolve fine detail. However, MRI is extremely sensitive to motion from the cardiac and respiratory cycles, which cause severe image artefacts. To reduce these artefacts, synchronisation (gating) to these physiological cycles is required.

Successful gating itself, however, can be difficult to achieve:
· Severe interference from the MR gradient system can cause problems in obtaining clean physiological signals from which gating information is derived.
· Once gating information has been derived, a suitable intra-respiratory acquisition window has to be defined which allows ECGs within the window to be used for MRI signal acquisition.
· Physiological rates of small animals can vary due to changes in thermal or pharmacological response; these variations can invalidate the defined acquisition window, hence introducing motion artefacts.
· Unfortunately, using double-gating (i.e. cardiac and respiratory gating) creates another form of image artefact that has to be minimised.

To overcome these problems, the Oxford team has designed a cardiac and respiratory gating device that is immune from gradient system interference, is adaptive and flexible to changes in physiological rates, and minimises relaxation effects. The inventors have developed a prototype of the device that is capable of minimising image artefacts so that the resultant images are clearer, and therefore significantly better for identification purposes than those obtained using existing methods.

Isis Innovation, Oxford University’s technology transfer company, has filed a patent application on the gating device and is actively looking for companies interested in utilising it.