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MRI contrast using solid‐state, B 1 ‐distorting, microelectromechanical systems (MEMS) microresonant devices (MRDs)
Author(s) -
Ciocan Razvan,
Lenkinski Robert E.,
Bernstein Jonathan,
Bancu Mirela,
Marquis Robert,
Ivanishev Alex,
Kourtelidis Fotini,
Matsui Aya,
Borenstein Jeffrey,
Frangioni John V.
Publication year - 2009
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21906
Subject(s) - materials science , microelectromechanical systems , resonator , nuclear magnetic resonance , scanner , signal (programming language) , electromagnetic coil , capacitor , radiofrequency coil , micrometer , radio frequency , biomedical engineering , optoelectronics , optics , physics , electrical engineering , voltage , quantum mechanics , computer science , programming language , medicine , engineering
Presently, signal generation in MRI depends on the concentration and relaxivity of protons or other MR‐active nuclei, and contrast depends on local differences in signal. In this proof‐of‐principle study, we explore the use of nonchemical, solid‐state devices for generating detectable signal and/or contrast in vitro and in vivo. We introduce the concept of microresonant devices (MRDs), which are micron‐sized resonators fabricated using microelectromechanical systems (MEMS) technology. Fifteen‐micrometer (15‐μm)‐thick, coil MRDs were designed to resonate at the 3T Larmor frequency of protons (127.7 MHz) and were fabricated using tantalum (Ta) oxide thin‐film capacitors and copper‐plated spiral inductors. The performance of MRDs having final diameters of 300, 500, and 1000 μm were characterized in saline using a radio frequency (RF) scanning microscope and a clinical 3T MR scanner. The measured B 1 fields of 300 μm to 1000 μm MRDs ranged from 3.25 μT to 3.98 μT, and their quality factors (Q) ranged from 3.9 to 7.2. When implanted subcutaneously in the flank of a mouse, only MRDs tuned to the resonant frequency of protons generated a measurable in vivo B 1 field. This study lays the foundation for a new class of solid‐state contrast agents for MRI. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.