Abstract: A radio-frequency coil, for nuclear magnetic resonance imaging at Larmor frequencies associated with a magnetic field of greater than about 0.5 Tesla, comprises a slotted-tube radio-frequency resonator having an elliptical cross-section. First and second complementary outer resonator portions have central bands connecting juxtaposed wing structures; the end of each of the four wings is spaced from a complementary wing portion of the other outer portion and capacitively coupled thereto. An inner structure has a pair of elliptical guard rings placed substantially in registration with the elliptical portions of the outer structure wing portions. The eccentricity ratio of the elliptical cross-section of the resonator and the resonator dimensions are arranged to provide an interior volume into which a human head or body extremity can be placed for imaging purposes.

Abstract: An MRIS gradient coil assembly 2A comprising a first coil layer comprising a first conductive coil portion 3X and a second coil layer comprising a second conductive coil portion 3Y. A first screening layer 6X is disposed between the first 3X and second 3Y coil layers and comprises at least one sheet of screening material. At least one insulating layer 4X comprising insulating material is provided between the first 3X conductive coil portion and the first screening layer 6X. Further the assembly comprises at least one discrete contact means 7 electrically connecting the first conductive coil portion 3X to the sheet of screening material 6X while the sheet of screening material 6X is kept from electrically contacting with the first conductive coil portion 3X, except via the at least one discrete contact means, by the at least one layer of insulating material 4X. The screening material might typically comprise a semi-conductive sheet.

Abstract: There is described a quadrature radio frequency (RF) coil design to be used with appropriate magnetic resonance imaging (MRI) hardware to obtain images of the human body. The design provides good RF field homogeneity over a volume suitable for thoracic diagnostic imaging, and operates in quadrature mode as a transmit and/or receive coil. The design is for use with a 0.33 tesla permanent, C shaped magnet with a vertical main field but is of general applicability. The coil includes two parallel annular coils connected at top and bottom by two plate conductors. The plates are split longitudinally and transversely and connected across the splits by capacitors to define two modes of resonant oscillation which can be tuned separately and independently to the same frequency, where the modes define fields which are mutually orthogonal. The fields are at right angles to the magnetic field and to the plate conductors so that the sample can be inserted through the openings at right angles to the plates.

Abstract: A distributed impedance circuit MR coil design comprised of a transmission line tunable cavity resonator which is well suited for but not limited to use at high frequencies and for large volumes such as in high field (e.g. 4.1 tesla) clinical MR applications. The distributed circuit transmission line resonator is designed for high frequency, large conductive volume applications where conventional lumped element coil designs fail. A resonant coaxial cavity is variably tuned to the Larmor frequency of interest by tunable transmission line elements. The resonator is effective for large head and body sized volumes, high efficiencies, and broad tuning ranges to frequencies of 500 MHz. The B.sub.1 homogeneity of the resonator is a function of the electromagnetic properties of the load itself. Maxwell's equations for the fully time-dependent B.sub.1 field predicts "coil" homogeneity with finite-element models of anatomic structure.

Abstract: An MRI system RF transmit antenna arrangement 3 including an antenna 5 including a length of coaxial cable 51 with an electrically conductive core 52 and an electrically conductive outer shield 53 through which the core runs, with the core having a feed point 52a arranged for electrical connection to an RF source and at least one break 53a being provided in the electrically conductive outer shield partway along the length of coaxial cable so as to divide the electrically conductive outer shield 53 into at least two axially spaced shield portions such that at least one of the shield portions acts as a radiating element when an RF source is connected to the feed point 52a.

Abstract: According to some aspects, a low-field magnetic resonance imaging system is provided. The low-field magnetic resonance imaging system comprises a magnetics system having a plurality of magnetics components configured to produce magnetic fields for performing magnetic resonance imaging, the magnetics system comprising, a B0 magnet configured to produce a B0 field for the magnetic resonance imaging system at a low-field strength of less than 0.