Problem
Gradient-echo magnetic resonance imaging (MRI) is used extensively to reveal the structure, and measure the function, of different areas of the body. One particularly exciting application is functional MRI, which can be used to produce maps of brain activity in a subject performing a mental task. Unfortunately signal dropout, caused by differences in the magnetic susceptibilities of materials in the human body, adversely affects gradient-echo images. As a consequence there are areas of the image where the structure and function cannot be determined. This is a particular problem in functional MRI where, for example, it is not currently possible to measure brain activity in areas such as the orbitofrontal cortex and inferior temporal lobes.
Solution
Researchers at King’s have developed a new method for designing the radiofrequency pulses used in gradient-echo based imaging [Wastling & Barker, 2014]. Their technique produces pulses that dramatically reduce the problem of signal dropout. The pulses have a quadratic phase profile that cancels the phase induced by the susceptibility differences in the body. The new pulses can be tailored for specific applications and parts of the body.
Applications
These novel radiofrequency pulses have been shown to reduce signal dropout in both structural and functional gradient echo MRI over a range of MRI scanner field strengths. It is thought that they will be particularly useful on high field MRI systems and extremity scanners (e.g. knee scanners) where the inhomogeneity of the magnetic field is more apparent.
Benefits
The novel radiofrequency pulses result in gradient echo images with significantly less signal dropout. Compared to existing methods aimed at reducing dropout this novel method does not increase imaging time or reduce spatial coverage. In addition, it is non-invasive and does not require any additional specialist hardware.
A B
Figure A: Conventional gradient-echo ECHO Planar Imaging (EPI) MRI image with signal dropout in the inferior temporal lobes. B: Gradient-echo EPI MRI image acquired with the novel RF pulse demonstrating reduction in the amount of signal dropout
IP Position
A preliminary US patent application was filed as a priority application (on 6 Nov 2013) and this has been followed (24 Oct 2014) by a Full US Patent Application (Application number: US 14/522,813). This patent application published on 7 May 2015 with publication number US 2015/0123662.
Opportunity
We are keen to identify commercial partners interested in licensing this technology for MRI applications. Field exclusivity is available.