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#12 - A specific radio frequency coil system which improves the resolution of high-field MRI
Long Title: Multilayered RF Coil System for Improving Transmit B1 Field Homogeneity in High-Field MRI
NIH Reference No.: E-020-2007
Executive Summary
General Description
A ballpark of 100 billion dollars a year is spent on medical imaging in the US alone. Imaging techniques, such as MRI, are essential to correctly diagnose a range of diseases by producing cross-sectional views of the body without damaging the living tissue. The availability of MRI units has rapidly increased worldwide over the past decade. In 2009, 91.2 MRI scans per 1,000 populations in the US were reported.
The invention relates to a device and method that greatly improves interventional high-field MRI. One of the unmet needs for high field MRI is the control of the transverse RF magnetic (B1) field, which helps to minimize contrast and sensitivity variations over the object. Currently MR images become less uniform as the magnetic field increases, introducing image distortions. The invention improves the high-field homogeneity, delivering better image quality. The current design can be readily implemented on existing MRI coil systems.
Scientific Progress
The inventors used a novel B1 homogenization approach by coupling an inner-layer surface coil array to an outer-layer volume transmit coil. Theoretical analysis on simulated data was used to demonstrate the advantages of current technology. The homogeneity of the field was improved by 1/3 for 7T brain imaging. The advantage of this method over current B1 homogenization methods is the independence of RF channels and readily adaptation to existing coil systems.
Using a non-spherical phantom mimicking the dielectric properties of the head, the inventors further demonstrated that the prototype can significantly improve the B1 field homogeneity in tissue. It was shown that a resonant loop aligned with a polarized B1 field can provide a 6-fold enhancement when tuned to less than 3% of the field frequency. Further analysis shows that the field enhancement at the center of a circular loop is nearly independent of the loop radius.
Future Direction
Strengths
Weakness
Patent Status
U.S. Pat: 8,125,225 issued Feb. 28, 2012
Publications
Wang S et al., IEEE Trans Med Imaging. 2009 Apr;28(4):551-4. PMID: 19336276
Merkle H et al., Magn Reson Med. 2011 Sep;66(3):901-10. PMID: 21437974
Inventor Bio
Alan Koretsky (NINDS)
Dr. Koretsky received his B.S. degree from the Massachusetts Institute of Technology and Ph.D. from the University of California at Berkeley. He performed postdoctoral work in the NHLBI at NIH studying regulation of mitochondrial metabolism using optical and NMR techniques. Dr. Koretsky spent twelve years on the faculty in the Department of Biological Sciences at Carnegie Mellon University where he was the Eberly Professor of Structural Biology and Chemistry. In summer 1999, he moved to NINDS as Chief of the Laboratory of Functional and Molecular Imaging and Director of the NIH MRI Research Facility. Dr. Koretsky's laboratory is interested in two main areas. They are actively developing novel imaging techniques to visualize brain function and study the regulation of cellular energy metabolism combining molecular genetics with non-invasive imaging tools.
Jozef Duyn (NINDS)
Dr. Duyn received his M.Sc. and Ph.D. degrees in physics at the University of Delft, Holland where he was involved with the development of X-ray diffraction techniques, as well as the early development of magnetic resonance imaging (MRI). During his postdoctoral assignments at the University of California, San Francisco, and at NIH, his research focused on the study of human brain physiology, as measured by spectroscopic and functional MRI techniques. Dr. Duyn moved to NINDS in 2000.
NIH Reference No.: E-020-2007
Executive Summary
- Invention Type: Class II Device
- Patent Status: US Application No. 60/900,972, PCT Application No. PCT/US2008/001911, U.S. Pat: 8,125,225 issued 2012-02-28
- LINK: http://www.ott.nih.gov/technology/e-020-20070
- NIH Reference Number: E-020-2007
- NIH Institute or Center: National Institute of Neurological Disorders and Stroke (NINDS)
- Disease focus: Imaging/MRI
- Basis of Invention: Hardware
- How it works: Device and method provide greater improvements in the area of in High-Field MRI, improving the field homogeneity
- Lead Inventors: Alan Koretsky (NINDS), Jozef Duyn (NINDS), Shumin Wang (NINDS), Hellmut Merkle (NINDS)
- Development Stage: Prototype available
- Novelty: New system and method for improvement in high-field uniformity in MRI applications
- Clinical Applications:
- High-Field MRI
- Improvement for MR Image Uniformity
- High-Field MRI
General Description
A ballpark of 100 billion dollars a year is spent on medical imaging in the US alone. Imaging techniques, such as MRI, are essential to correctly diagnose a range of diseases by producing cross-sectional views of the body without damaging the living tissue. The availability of MRI units has rapidly increased worldwide over the past decade. In 2009, 91.2 MRI scans per 1,000 populations in the US were reported.
The invention relates to a device and method that greatly improves interventional high-field MRI. One of the unmet needs for high field MRI is the control of the transverse RF magnetic (B1) field, which helps to minimize contrast and sensitivity variations over the object. Currently MR images become less uniform as the magnetic field increases, introducing image distortions. The invention improves the high-field homogeneity, delivering better image quality. The current design can be readily implemented on existing MRI coil systems.
Scientific Progress
The inventors used a novel B1 homogenization approach by coupling an inner-layer surface coil array to an outer-layer volume transmit coil. Theoretical analysis on simulated data was used to demonstrate the advantages of current technology. The homogeneity of the field was improved by 1/3 for 7T brain imaging. The advantage of this method over current B1 homogenization methods is the independence of RF channels and readily adaptation to existing coil systems.
Using a non-spherical phantom mimicking the dielectric properties of the head, the inventors further demonstrated that the prototype can significantly improve the B1 field homogeneity in tissue. It was shown that a resonant loop aligned with a polarized B1 field can provide a 6-fold enhancement when tuned to less than 3% of the field frequency. Further analysis shows that the field enhancement at the center of a circular loop is nearly independent of the loop radius.
Future Direction
- In vivo data in human subjects is needed to confirm the simulated analysis
Strengths
- Improvement of MR image uniformity
- Can be implemented with existing MRI coil systems
- Compared to other homogenization methods, this approach has the distinct advantage that it can be implemented without the need for independent radio frequency channels, thereby reducing MRI system complexity
Weakness
- No in vivo data reported
Patent Status
U.S. Pat: 8,125,225 issued Feb. 28, 2012
Publications
Wang S et al., IEEE Trans Med Imaging. 2009 Apr;28(4):551-4. PMID: 19336276
Merkle H et al., Magn Reson Med. 2011 Sep;66(3):901-10. PMID: 21437974
Inventor Bio
Alan Koretsky (NINDS)
Dr. Koretsky received his B.S. degree from the Massachusetts Institute of Technology and Ph.D. from the University of California at Berkeley. He performed postdoctoral work in the NHLBI at NIH studying regulation of mitochondrial metabolism using optical and NMR techniques. Dr. Koretsky spent twelve years on the faculty in the Department of Biological Sciences at Carnegie Mellon University where he was the Eberly Professor of Structural Biology and Chemistry. In summer 1999, he moved to NINDS as Chief of the Laboratory of Functional and Molecular Imaging and Director of the NIH MRI Research Facility. Dr. Koretsky's laboratory is interested in two main areas. They are actively developing novel imaging techniques to visualize brain function and study the regulation of cellular energy metabolism combining molecular genetics with non-invasive imaging tools.
Jozef Duyn (NINDS)
Dr. Duyn received his M.Sc. and Ph.D. degrees in physics at the University of Delft, Holland where he was involved with the development of X-ray diffraction techniques, as well as the early development of magnetic resonance imaging (MRI). During his postdoctoral assignments at the University of California, San Francisco, and at NIH, his research focused on the study of human brain physiology, as measured by spectroscopic and functional MRI techniques. Dr. Duyn moved to NINDS in 2000.
