High field magnetic resonance imaging at field strengths at or above 7 tesla appears to be one of the most promising techniques for the early detection of neurological pathologies. Currently beyond the reach of most MRI system manufacturers, this imaging technology is beset with new technological difficulties. The CEA Iseult project team (IRFU and I2BM) has now overcome one of these problems; the homogeneous excitation of atomic nuclei using parallel transmission. This is needed in order to achieve a uniform excitation of the proton spins in living tissue, which in turn enables images of the human brain to be obtained without areas of shadow or loss of contrast. In vivo images recently obtained at 7 tesla using parallel transmission are the first to be achieved in Europe. They represent the crowning achievement of a successful collaboration between the two institutes. This work has also resulted in the filing of a number of patents. While there are around fifteen 7-tesla MRI scanners currently installed worldwide, only five or six research centers are capable of bringing together all the expertise deployed by the DSM-DSV collaboration in order to develop all the technologies needed for parallel transmission. These include antenna design (IRFU/SACM) and the associated electronics (I2BM/NeuroSpin), the electromagnetic simulation of the antenna-patient coupling (IRFU/SACM), the development of MRI sequences for the acquisition of magnetic field maps (I2BM/NeuroSpin), the analysis and monitoring of power dissipated in the tissue, and the development of parallel transmission procedures (I2BM/NeuroSpin), together with design services (IRFU/SIS) and the development of specialist test and measurement equipment (IRFU/SEDI).
Authors : A. Amadon, N. Boulant, F. Lethimonnier, M. Luong
Contacts
Irfu : michel.luong@cea.fr
NeuroSpin : franck.lethimonnier@cea.fr
Notes :
[1] Consortium Iseult/Inumac composé par le CEA, l’Université de Freiburg (Allemagne), Siemens Medical Solutions (Germany), Bruker BioSpin GmbH (Germany), Guerbet (France) et Alstom (France).
[2] http://www.imaios.com/fr/e-Cours/e-MRI/codage-spatial-signal/gradients-codage.
[3] Résonateur linéaire d’une antenne haute fréquence pour appareil d’imagerie par résonance magnétique nucléaire, G. Ferrand, M. Luong, A. France, numéro de dépôt de brevet 10 50905, février 2010.
[4] Method and Apparatus for Compensating for B1 Inhomogeneity in Magnetic Resonance Imaging by Nonselective Three-Dimensional Tailored RF Pulses, A. Amadon & M. Cloos, F263-375 patent pending, April 2010.
[5] KT points: Fast Three-Dimensional Tailored RF Pulses for Flip-Angle Homogenization Over an Extended Volume, M.A. Cloos, N. Boulant, M. Luong, G. Ferrand, C.J. Wiggins, E. Giacomini, A. France, D. Le Bihan, A. Amadon, Oral presentation 102, Proc. Intl. Soc. Mag. Reson. Med. 18, Stockholm (2010).
[6] B1-mapping of an 8-channel TX-array over a human-head-like volume in less than 2 minutes : the XEP sequence, A.Amadon, N. Boulant, M.A. Cloos, E. Giacomini, C.J. Wiggins, M. Luong, G. Ferrand, H-P Fautz, P2828, Proc. Intl. Soc. Mag. Reson. Med. 18, Stockholm (2010).
[7] A Geostatistical Approach to Denoise and Interpolate Experimental Complex-Valued B1 Maps, G. Ferrand, M. Luong, P. Chauvet, MA. Cloos, A. Amadon, P1471, Proc. Intl. Soc. Mag. Reson. Med. 18, Stockholm (2010).
[8] Local SAR reduction in parallel excitation based on channel-dependent Tikhonov parameters, M. Cloos, M. Luong, G. Ferrand, A. Amadon, D. LeBihan, and N. Boulant, Journal of Magnetic Resonance Imaging, in press.
[9] Parallel excitation of nuclear spins with local SAR control, patent pending, September 2009.
[10] Specific absorption rate monitor for in-vivo parallel transmission at 7 Tesla, M. A. Cloos, N. Boulant, M. Luong, G. Ferrand, D. Le Bihan and A. Amadon, Poster presentation P3871, Proc. Intl. Soc. Mag. Reson. Med. 18, Stockholm (2010).
Writers: A. Amadon, N. Boulant, F. Lethimonnier, M. Luong
Contacts:
Irfu: michel.luong@cea.fr
NeuroSpin: franck.lethimonnier@cea.fr
• Irfu expertise working for the society
• Accelerators, Cryogenics and Magnetism Division (DACM) • The Electronics, Detectors and Computing Division • The Systems Engineering Division
• ISEULT
