摘要:
Aspects relate to providing radio frequency components responsive to magnetic resonance signals. According to some aspects, a radio frequency component comprises at least one coil having a conductor arranged in a plurality of turns oriented about a region of interest to respond to corresponding magnetic resonant signal components. According to some aspects, the radio frequency component comprises a plurality of coils oriented to respond to corresponding magnetic resonant signal components. According to some aspects, an optimization is used to determine a configuration for at least one radio frequency coil.
摘要:
Systems and methods for simultaneous radio frequency (“RF”) transmission and reception for nuclear magnetic resonance applications, such as magnetic resonance imaging (“MRI”) are described. The system includes a simultaneous transmit and receive (“STAR”) control system that compensates for the effects of load changes in a radio frequency (“RF”) coil due to the inevitable motion of living subjects (e.g., from subject motion, respiration, swallowing). The system also maintains a high transmit-receive isolation, even when scanning a subject using a continuous RF broad band sweep excitation.
摘要:
Phase variations of the transverse magnetization in magnetic resonance induced by superimposed physical phenomenae or by intrinsic deviations of the main magnetic B0 field are separated from Feature Space set by demodulation and deconvolution, either by electrical circuits or by equivalent computational methods, permitting mapping and measurement of these induced phase variations independent of Feature Space.
摘要:
Nuclear magnetic resonance (NMR) logging tools may be configured for situation-dependent NMR logging operations by including two dissimilar coils that may function in four different modes of operation based on logging conditions including: a resistivity of the fluid, a diameter of the wellbore, a depth into the subterranean formation of the volume of investigation, or a combination thereof. For example, an NMR logging tool with a z-coil and a transversal coil may be useful in generating in a volume of investigation of a subterranean formation either (1) a transversal radiofrequency (RF) excitation with the transversal coil or (2) a quadrature RF excitation with both the z-coil and the transversal coil, where the choice of transversal or quadrature RF excitation is based on the logging conditions; and detecting an NMR signal from the subterranean formation with one of: (1) the transversal coil or (2) both the z-coil and the transversal coil.
摘要:
The disclosure of the present invention provides for an imaging apparatus and methods for imaging the cranio-cervical junction of a patient using magnetic resonance. The apparatus is adapted to slide over the patient's head, and includes a saddle element and a solenoid element. The saddle element has a length that extends along a superior-inferior axis of the patient, and a circumference along an axial plane of the patient when the apparatus is slid over the patient's head, so as to define a substantially cylindrical volume. The solenoid element attaches to the saddle element at about a midpoint of the saddle element's length, so as to be positioned along an axial plane of the patient when the apparatus is slid over the patient's head. This configuration allows for the cranio-cervical junction of the patient to be positioned in the cylindrical volume when the apparatus is slid over the patient's head.
摘要:
The embodiments relate to a magnetic resonance coil for a magnetic resonance device with a measuring chamber for an examination object and a cylindrical birdcage antenna arrangement having a plurality of antenna elements disposed at least in some areas around a measuring chamber in the form of circumferential antenna rings or axial outer rods connecting the rings. The antenna elements include electric components, e.g., reactive capacitive and/or inductive systems. The magnetic resonance coil also has at least two antenna feeds, e.g., phase-offset in relation to one another by 90°, by which radio-frequency energy is able to be supplied to the birdcage antenna arrangement. The antenna feeds include at least one symmetrical feed via at least one of the electric components of the birdcage antenna arrangement as well is at least one assigned asymmetrical feed between the birdcage antenna arrangement and a screen connection.
摘要:
In one aspect, the present invention is a method for detecting spinal abnormalities using magnet resonance imaging. The method comprises positioning a patient in an upright posture in an imaging volume of a magnet resonance imaging magnet with the spine of the patient adjacent to an antenna and capturing magnetic resonance imaging signals from a first portion of the patient's spine using the antenna with the patient positioned in a first position. The method may further comprise adjusting the patient position along a substantially vertical direction to a second position and capturing magnetic resonance imaging signals from a second portion of the patient's spine using the antenna with the patient positioned in the second position.
摘要:
An apparatus for magnetic resonance imaging includes a magnet, a patient support, and a contoured quadrature coil. The contoured quadrature coil includes a ring coil and an angled butterfly coil. The angled butterfly coil may have a front outer section, an inner section, and a back outer section. The front outer section and the back outer section may be oriented diagonally from the plane of the ring coil such that a portion of the front outer section and/or the back outer section are disposed above the plane of the ring coil and a portion of the front outer section and/or the back outer section are disposed below the plane of the ring coil. Thus, the planes of the front and back outer sections may be angled with respect to each other, and the inner section may be substantially pyramidal and disposed along or below the plane of the ring coil.
摘要:
In some aspects, a downhole nuclear magnetic resonance (NMR) tool includes a magnet assembly and an antenna assembly. The NMR tool can operate in a wellbore in a subterranean region to obtain NMR data from the subterranean region. The magnet assembly produces a magnetic field in a volume about the wellbore. The antenna assembly produces excitation in the volume and acquires an azimuthally-selective response from the volume based on the excitation. The antenna assembly can include a transversal-dipole antenna and a monopole antenna.
摘要:
A parallel plate waveguide forms a volume coil used for magnetic resonance imaging and spectroscopy. The waveguide includes a first conductor arranged on a first side of the waveguide and a second conductor arranged on a second side of the waveguide. Excitation of the first conductor and the second conductor creates a transverse electromagnetic field between the first conductor and the second conductor which causes a target within the volume coil to emit radio frequency signals used for producing an image of the target.