A petal resonator volume coil for MR neuroimaging
A.O. Rodríguez*, S.S. Hidalgo**, R. Rojas***, F.A. Barrios****
* Centro de Investigación en Imagenologia e Instrumentación Médica, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco 186, México, D.F., 09340. México., Telephone No./FaxNo.: (5255) 8502–4569, e–mail: arog@xanum.uam.mx .
Corresponding author.
** Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD, Britain.
Present Address: Imaging Research Laborarories, Robarts Research Institute, 100 Perth Drive, London, Ontario, CANADA N6A5K8.
**** Instituto de Neurobiología, UNAM–Juriquilla, Juriquilla 76230, Queretaro, México.
Recibido el 8 de junio de 2004
Aceptado el 24 de abril de 2006
Abstract
A variant of the petal resonator (PERES) coil was developed for magnetic resonance neuroimaging applications. It is formed by eight 2 cm–radius petal coils around a central circular–shaped coil with a total radius of 10 cm. As dictated by the theory proposed by Mansfield in 1988, the small coil centers were separated by three times the petal coil radius to avoid mutual inductance between them. The present configuration can easily accommodate a head shape and can be placed nearer the subject to be imaged than other volume coils. Enhancement factor maps were computed to study the coil design performance based on the PERES coil foundations. Coil uniformity was theoretically investigated using the quasi–static approach for various petal coil radii. An 8–petal band coil was built, and in vivo and in vitro experiments were conducted on a clinical MR imager together with standard imaging sequences. Brain images of a healthy volunteer are reported to show the utility of the coil.
Keywords: MR neuroimaging; resonator; coil; sensitivity; uniformity.
]]> Resumen
Se desarrolló una variante de la antena superficial resonador de pétalo para neuroimagenología por resonancia magnética. El prototipo está constituido por ocho pétalos circulares de 2 cm de radio que se colocan alrededor de una espira circular con un radio de 10 cm. Como lo establece la teoría de la antena PERES, los centros de los pétalos están separados a una distancia de tres veces el radio del pétalo para evitar la inductancia mutua entre ellas. El presente arreglo se ajusta fácilmente a la forma de la cabeza, permitiendo una mejor proximidad comparada con las antenas tradicionales de volumen jaula de perico y el resonador TEM. Se calcularon mapas de mejoramiento para estudiar el desempeno de la antena basada en los fundamentos de la antena PERES. La uniformidad de la antena se estudió de manera teórica usando el enfoque casi estático para el cociente señal a ruido y varios arreglos de pétalos. Se construyó una antena de 8 pétalos y se hicieron experimentos en vivo y en vitro con un sistema de IRM clínico, y secuencias estandares de imagenologia. Se reportan imagenes cerebrales para mostrar su viabilidad.
Descriptores: Neuroimagenología RM; resonador; antena; sensibilidad; uniformidad.
PACS: 87.61.–c; 87.61.Ff; 84.32.Hh
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Acknowledgments
Authors wish to express their gratitude to the American Britsh Cowdray Hospital Tacubaya, General Electric Sistemas Medicos México and Schering Mexicana for their invaluable support for this research. We also thank the Secretariat of Public Education (FOMES–SEP) for a research grant: P/FPMES 98–35–11, DES UAM 98–05. SS would like to thank to CONACYT–Mexico for a Ph D scholarship. Support from Inovamedica is gratefully acknowledged.
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