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Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coilsRelated Patent Categories: Metal Working, Method Of Mechanical Manufacture, Electrical Device Making, Electromagnet, Transformer Or Inductor, By Assembling Coil And CoreMethod and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060277749, Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation application of U.S. patent application Ser. No. 11/224,436, filed Sep. 12, 2005, which is a continuation application of U.S. patent application Ser. No. 09/974,184, filed Oct. 9, 2001, which is a continuation of provisional application Ser. No. 60/239,185, filed, Oct. 9, 2000, and entitled "Microstrip Resonator RF Surface and Volume Coils and Methods for NMR Imaging and Spectroscopy at High Fields," each of which are hereby incorporated herein by reference. TECHNICAL FIELD OF THE INVENTION [0003] This invention pertains generally to magnetic resonance imaging (MRI) and more specifically to surface and volume coils for MRI imaging and spectroscopy procedures. BACKGROUND OF THE INVENTION [0004] Surface and volume coils are used in MRI imaging or spectroscopy procedures in order to obtain more accurate or detailed images of tissue under investigation. Preferably, a MRI coil performs accurate imaging or spectroscopy across a wide range of resonant frequencies, is easy to use, and is affordable. Further, the operating volume inside the main magnet of many MRI systems is relatively small, often just large enough for a patient's head or body. As a result, there is typically little space available for a coil in addition to the patient. Accordingly, it is advantageous if a surface or volume coil itself occupies as little space as possible. [0005] In high fields (3 Tesla and beyond), due to the high Larmour frequencies required, radiation losses of RF coils become significant which decreases a coil's quality factor or Q factor, and a low Q factor can result in low signal-to-noise ratio (SNR) in MRI procedures. One existing solution to reducing radiation losses is adding a RF shielding around the coil(s). The RF shielding, however, usually makes the physical size of RF coil much larger, which as noted above is not desired in the MR studies, especially in the case of high field operations. SUMMARY OF THE INVENTION [0006] According to certain example embodiments of the invention there are provided a MRI coil formed of microstrip transmission line. According to various embodiments of the invention, MRI coils according the present invention are easy to manufacture with relatively low cost components, and compact in design. In addition, the coil's distributed element design provides for operation at relatively high quality factors and frequencies and in high field (4 Tesla or more) environments. Further, microstrip coils according to the present invention exhibit relatively low radiation losses and require no RF shielding. As a result of not requiring RF shielding, the coils may be of compact size while having high operating frequencies for high field MR studies, thus saving space in the MRI machine. Further, the methods and apparatus of the present invention are not just good for high frequency MR studies, but also good for low frequency cases. BRIEF DESCRIPTION OF THE DRAWING [0007] FIG. 1 illustrates a method according to one example embodiment of the invention. [0008] FIGS. 2-14 illustrate various example embodiments of the apparatus of the invention. DETAILED DESCRIPTION OF THE INVENTION [0009] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only be the appended claims. Method Embodiments [0010] According to a first method embodiment of the invention, as illustrated in FIG. 1, a target is positioned within the field of a main magnetic field of a magnet resonance imaging (MRI) system, at least one coil is positioned proximate the target wherein the coil is constructed using at least one microstrip transmission line, and the main magnet and the MTL coil are used to obtain MRI images from the target. According to one use of the microstrip transmission line (MTL) coil, it is operated as a receiver (pickup coil) or a transmitter (excitation coil) or both during an imaging procedure. As used herein the term "MTL coil" generally refers to any coil formed using a microstrip transmission line. [0011] The microstrip transmission line, according to one example design, is formed of a strip conductor, a ground plane and a dielectric material that may be air, a vacuum, low loss dielectric sheets such as Teflon or Duroid, or liquid Helium or liquid Nitrogen. Further, the strip conductor or ground plane are, in one embodiment, formed in whole or in part from a non-magnetic conductive material such as copper or silver. According to another example embodiment of the invention, the ground planes for multiple strip conductors are arranged in one single piece foil so as to reduce radiation loss. [0012] In another example embodiment, the MTL coil is a volume MTL coil having a plurality of microstrip transmission lines. In still another example embodiment, the volume MTL coil is detuned using PIN diodes. In yet another example embodiment, the MTL coil includes bisected ground planes and the PIN diodes are positioned in the gap of the bisected ground planes. [0013] According to still other example embodiments of the methods of the invention, a MTL coil is tuned by varying capacitive termination of the MTL coil wherein, for example but not by way of limitation, the MTL coil is tuned by varying capacitive termination on each end of the MTL coil. [0014] In still other example embodiments of the method, the microstrip transmission line is arranged in a rectangular or circular configuration, or, in the alternative, in an S shape. In one advantageous embodiment, the MTL coil is constructed using at least two turns to improve the homogeneity of the magnetic field characteristics. [0015] In still other example embodiments, one or more lumped elements are connected to the transmission line and operated so as to match the impedance of the line. [0016] In yet still another embodiment, an MTL coil is operated in a resonant mode by bisection of the ground plane and tuning of the resonance by adjusting displacement of the ground planes. In another embodiment, at least two of the MTL coils are operated in a quadrature mode. In still another embodiment, a coil is arranged so as to operate as a ladder MTL coil. In yet another embodiment, at least two MTL coils are arranged and operated as a half volume MTL coil. [0017] In still another example embodiment, an inverted imaging MTL coil is formed wherein the dielectric material is positioned in a plane on the side of the strip conductor plane in the direction of the field, and wherein coupling is capacitive. [0018] In yet another example embodiment of the methods of the invention, the MTL coil is driven using a capacitive impedance matching network. In still another example embodiment of the methods of the invention, the dielectric constant Er is adjusted to change the resonant frequency of the MTL coil. Continue reading about Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils... Full patent description for Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils or other areas of interest. ### Previous Patent Application: Methods for fabricating giant magnetoresistive (gmr) devices Next Patent Application: Method of mounting electro-conductive rings on a non-conductive tubular body Industry Class: Metal working ### FreshPatents.com Support Thank you for viewing the Method and apparatus for magnetic resonance imaging and spectroscopy using microstrip transmission line coils patent info. IP-related news and info Results in 0.35161 seconds Other interesting Feshpatents.com categories: Computers: Graphics , I/O , Processors , Dyn. Storage , Static Storage , Printers 174 |
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