Novel coil supports cardiac MR without phased-array technology

Gains come from sensitivity, homogeneity

A new type of MR coil that promises to improve the quality of deep organ spectroscopy and imaging using relatively simple hardware has been developed by U.K. researchers at Oxford University. Their novel single-coil system offers a means of performing cardiac MRI and MRS on low-tech scanners not equipped with phased-array coil technology.

The new radio-frequency coil optimizes sensitivity and MR field homogeneity, two critically important factors when doing cardiac MRI and MRS, according to Dr. Paul Cassidy, design engineer with the British Heart Foundation's molecular cardiology group at Oxford. The art of RF coil design is balancing these two parameters.

Smaller coils offer better sensitivity but have lower field homogeneity due to the decreased field-of-view, he said. Increasing coil volume gives good homogeneity, but it comes at the expense of sensitivity.

High-performance MR scanners cope with this conundrum by using phased-array coil technology. In this approach, an array of closely configured surface coils provides high sensitivity as well as a large field-of-view. Scanners must also be fitted with an additional RF transmitter coil and multiple receiver channels. This increases their cost and complexity.

In contrast, the Oxford solution uses just one dedicated RF coil. This offers a less complex means of enhancing sensitivity and homogeneity.

Designed and engineered as part of a doctoral project, the coil was originally intended to be used for cardiac spectroscopy studies, Cassidy said. When researchers started testing their prototype on the single-coil MR scanner at the John Radcliffe Hospital in Oxford, however, they discovered that the coil was suitable for imaging the heart as well, thereby providing an added advantage in terms of cost-effectiveness.

Cassidy notes that the single-coil solution is unlikely to compete with commercially available multicoil systems for cardiac imaging. It offers instead a viable alternative to researchers and clinicians who wish to perform cardiac MRI but do not have access to equipment with parallel imaging capabilities. The technology may hold its own, however, in the MRS market, he said.

"There have been a lot of developments in cardiac MR," he said. "In terms of performing spectroscopy studies with this coil, there may be certain advantages in sensitivity. There are many issues related to the best way to obtain spectroscopy data using multiple coils."

Precise details of the coil remain under wraps while the lengthy procedures necessary to patent the novel technology are going on. This process is being handled by technology transfer company Isis Innovation, a wholly owned subsidiary of Oxford University. Founded in 1988 to protect and commercialize university-owned intellectual property, the rapidly growing company files a patent every week, on average, and spins off a company every two months.

Isis is now seeking a partner company to help realize the potential of the novel MR coil, said Dr. Amanda Nolte, physical science project manager at Isis.

"It would be very exciting to take this platform technology to a start-up company," she said. "But if a big company is interested, that would be great."